HPV Circulating Cell-Free DNA Kinetics in Cervical Cancer Patients Undergoing Definitive Chemoradiation

PURPOSE/OBJECTIVE(S)

The human papilloma virus (HPV) is a significant cause of cervical cancer and viral DNA can be detected in the blood of patients with cervical cancer (cfHPV-DNA). We hypothesized that detecting HPV cfDNA before, during and after chemoradiation (CRT) could provide insights into disease extent, clinical staging, and treatment response.

MATERIALS/METHODS

Forty-seven patients with cervical cancer were enrolled on this study between 2017 and 2022, either as part of a standard-of-care (SOC) treatment banking protocol (33 patients) or as part of a clinical trial combining a therapeutic HPV vaccine (PDS0101; Immunocerv, 14 patients). Longitudinal plasma samples were collected from each patient as baseline, during week 1, 3 or 5 of CRT. cfHPV-DNA was quantified using droplet digital PCR targeting the HPV E6/E7 oncogenes of 13 high-risk types based on analysis of cervical tumor genotype (AmpFire). Clinical covariates, including FIGO stage, primary tumor size, and treatment response were studied using appropriate statistical tests.

RESULTS

All 47 patients had detectable HPV cfDNA during CRT with 38 out of 47 having HPV type 16 detected. The median cfDNA at baseline was 24.5 copies/mL, with a range of 0 to 157,638 copies/mL. Of the 35 patients with at least three measurements, 20 (57%) had peak cfDNA counts at week 3, and 30 out of 35 showed a decline in cfDNA counts at week 5 compared to week 3. The proportion of patients who cleared cfDNA (<16 copies/mL) increased with each week of CRT, reaching 75% at week 5. Baseline cfDNA counts were associated with para-aortic nodal involvement (p<0.0001) but not with FIGO stage or gross tumor volume. A greater proportion of patients treated with therapeutic HPV-directed vaccine had clearance of cfDNA counts as compared to those treated with SOC (at week 3, 38% vs 5%, P = 0.02 and week 5, 79% vs 22%, P = 0.0054) CONCLUSION: HPV cfDNA levels change dynamically throughout definitive CRT and peak during the first 3 weeks for the majority of patients. Treatment with a therapeutic HPV vaccine was associated with a more rapid decline in cfHPV DNA. Further analysis of cfDNA kinetics could provide valuable information on the relationship between cfDNA levels, treatment response, and clinical outcomes.

Financial Improvements from Short Course Adjuvant Vaginal Cuff Brachytherapy (VCB) in Early Endometrial Cancer Compared to Standard of Care, "SAVE" Trial

PURPOSE/OBJECTIVE(S)

Early-stage endometrial cancer is often managed with hysterectomy followed by adjuvant VCB. Financial toxicity from cancer treatment is a strong driver of adherence. The SAVE trial is a multicenter, prospective randomized trial of standard of care (SoC) VCB doses delivered in 3-5 fractions per physician discretion compared to a 2-fraction course. We report on secondary cost endpoints, quantifying the financial impacts of shorter treatment courses on institutions and participating patients.

MATERIALS/METHODS

Technical (TechCs), professional (PCs), and total charges (TotCs) were collected prospectively and are reported as raw and Medicare-adjusted charges per patient. Geographic variations were standardized with CMS Geographic Practice Cost Indices (GPCI), and inflation was adjusted using the Consumer Price Index (CPI): Medical Care. Distance to treatment center was calculated from the patient's zip code to the corresponding treatment center. Cost of commutes was estimated through round-trip travel distance multiplied by average gas MPG for new vehicles by treatment year and state. Median income for each patient's zip code was estimated using 5-year Household income in 2021 inflation-adjusted dollars from the US Census. Mann-Whitney U, T- and Chi-square tests were used to compare characteristics between the two groups.

RESULTS

One hundred eight patients were analyzed. SoC VCB was delivered in 3, 4 and 5 fractions for 27/54 (50%), 11/54 (20%), and 16/54 (30%), respectively. Median total distance traveled per patient for SoC vs. experimental arms was 213 vs 137 miles (p = .12), and median cost of commute for patients was 36.3 vs 18.0 USD (p = .11). Compared to 2-fraction treatment, 5-fraction treatment resulted in longer travel distances (median 462 vs. 137 miles, p < 0.01) and increased travel costs (median 59.3 v. 18.0 USD, p = < 0.01). Median income by zip code for SoC v. experimental arms was 79,704 vs. 79,671 USD (p = 1.0). For SoC v. experimental arms, 11 (20%) vs 7 (13%) of patients had zip codes with median income in the lowest or second lowest quintiles (p = 0.5). Adjusted raw PCs per patient did not differ between SoC vs. experimental arms (9,159$ vs. 7,532$, p = 0.19). TechCs were significantly higher on the SoC arm (35,734$ vs. 24,696$ p = < 0.01), as were TotCs (44,892$ vs. 32,228$, p < 0.01;). Medicare-adjusted PCs, TechCs, and TotCs were higher for the SoC arm (Table 1).

CONCLUSION

Two-fraction VCB resulted in fewer treatments per patient, reduced cost of travel compared to longer courses, and an adjusted reduction in healthcare expenditures compared to standard of care. Ongoing work will include assessment of patient-reported financial toxicities.

Short Course Adjuvant Vaginal Cuff Brachytherapy (VCB) in Early Endometrial Cancer: Primary Endpoint Results of the SAVE Randomized Clinical Trial

PURPOSE/OBJECTIVE(S)

Prospective trials in early stage endometrial cancer demonstrate increased locoregional control with adjuvant radiotherapy for patients with high risk features. VCB is widely utilized, yet there is substantial practice variation and limited randomized data examining optimal dose/fractionation. We aimed to study the safety and efficacy of short course VCB compared to commonly used regimens.

MATERIALS/METHODS

We conducted a prospective, randomized, multicenter trial examining short course adjuvant VCB (11 Gy x 2 fractions at the surface) compared with other standard regimens (7 Gy x 3 fractions at 0.5 cm depth, 6 Gy x 5 fractions at the surface, or 5-5.5 Gy x 4 fractions at 0.5 cm depth). Eligible patients underwent hysterectomy and had pathologically confirmed endometrioid adenocarcinoma, serous, clear cell, or carcinosarcoma. Patients with stage I and II cancers were included, with lymphovascular invasion (LVI) required for stage IAG1. The primary outcome was Global Health Status measured by the EORTC QLQ-C30 with a pre-specified non-inferiority margin of 15 points. Secondary outcomes included patient-reported outcomes, toxicities as assessed by CTCAEv5, and patterns of recurrence. Data were collected at each brachytherapy fraction and at 1-, 6-, and 12-month follow-up.

RESULTS

One hundred eight patients were enrolled, 54 in each study arm. Data completion was 94%, 91%, and 77% at 1 month, 6 months, and 12 months, respectively. 70% of patients had endometrioid adenocarcinoma, 18% serous carcinoma, and 12% other histologies. 23% were FIGO grade 1, 33% grade 2, and 43% grade 3 or high risk histologies. The majority of patients were stage I (56% IA, 38% IB). 22% of patients had LVI. The QLQ-C30 Global Health Status for the experimental arm was within the predefined boundary and thus 2 fractions were non-inferior to standard of care at one month (p = 0.000005) and 12 months (p = 0.0005). Using EORTC EN24 for patient reported vaginal/sexual, urologic, and gastrointestinal symptoms, the change in mean patient reported symptom score from baseline to 1 month and baseline to 12 months were not significantly different between arms. Using CTCAEv5, 51 patients experienced short-term AEs related to study treatment, 20 in the experimental arm and 31 in the control arm (p = 0.053). All study treatment-related AEs were grade 1-2, except for two grade 3-4 AEs, both on the control arm. At median follow-up of 19 months, the isolated vaginal control rate in each arm was 100%. There was no significant difference in the total number of recurrences between study arms, with 3 distant and 3 distant/pelvic/vaginal recurrences in the experimental arm, and 2 distant, 2 pelvic, and 1 pelvic/vaginal recurrence in the control arm.

CONCLUSION

Short course VCB is safe with acceptable acute toxicity and non-inferior patient reported outcomes. Short course VCB improves patient convenience and may improve access to care for rural or underserved populations while providing similar local control.

Predictors of Poor Treatment Experience in Cervical Cancer Patients Receiving Definitive Chemoradiation and Brachytherapy Boost: A Prospective Study

PURPOSE/OBJECTIVE(S)

Cervical cancer patients experience high overall symptom burden. Here, we analyzed patient reported outcomes (PROs) to identify disease, treatment, or patient-related characteristics that can predict poor treatment experience.

MATERIALS/METHODS

Cervical cancer patients treated with definitive chemoradiation (CRT) at a single institution enrolled on a prospective trial evaluating PROs between 2021-2023 were included. Patients received PRO questionnaires at baseline (BL) and 2-7 days after final brachytherapy implant (post-BT). Data was collected using the EORTC-QLQ-C30, which is a validated metric scored on a 4-point Likert scale (1 = not at all, 2 = a little, 3 = quite a bit, 4 = very much). Poor treatment experience was defined as low physical function [score >2], significant overall symptom burden [> population mean], or substantial nausea/vomiting (N/V), diarrhea, pain, or fatigue [score >2] after BT. Potential predictors included age, menopause status, stage, radiation field size, BT modality (PDR vs HDR), marital status, high baseline financial toxicity [score >2], depression [score >2], worse social function [score >2] and poor emotional function [score >2]. Logistic regression modeling was performed and p<0.05 were considered significant.

RESULTS

A total of 36 patients completed BL and post-BT PRO metrics. Median age was 42 (range, 18-85), 22% (n = 8) of patients had localized disease, 75% (n = 27) had regional disease, and 3% (n = 1) had distant disease. Low BL social function was associated with high symptom burden after BT (HR 12.5, 95% CI 2.3-68.2, p = 0.004), significant N/V (HR 19.0, 95% CI 1.9-191.0, p = 0.012), high rates of fatigue (HR 9.29, 95% CI 1.6-54.8, p = 0.014), and overall poor physical function after treatment (HR 5.67, 95% CI 1.1-30.1, p = 0.042). High BL financial toxicity was predictive of elevated symptom burden after BT (HR 12.0, 95% CI 2.2-66.0, p = 0.004) and substantial fatigue (HR 7.33, 95% CI 1.5-36.7, p = 0.015). Significant depression at BL was also associated with high rates of N/V (HR 9.78, 95% CI 1.4-66.9, p = 0.02). Patient age, menopausal status, disease stage, radiation field size, BT modality, and marital status were not significantly predictive for symptom burden or physical function after treatment.

CONCLUSION

Patients with poor baseline social function, high financial toxicity, and depression are at risk for increased symptom burden. Screening for these factors may provide an opportunity to intervene early and improve patient treatment experience.

Radiation Oncology Practice Changes during the COVID-19 Pandemic

PURPOSE/OBJECTIVE(S)

The purpose of this study was to characterize the effects of institutional policies routine SARS-CoV-2 testing before treatment starts with mandatory quarantine periods for COVID-positive patients during the first year of the COVID19 pandemic across radiation oncology sections at our tertiary cancer center.

MATERIALS/METHODS

Electronic medical databases were queried to identify all patients treated with curative intent at a large urban cancer center and regional satellites a year prior to the pandemic (02/11/19-12/30/19; pre-pandemic) and the first year of the pandemic (03/11/20-12/30/20; post-pandemic). New treatment starts were filtered for those undergoing treatment under a single ICD-10 diagnosis and the first treatment in each time period for each patient. Chi-square tests were used for categorical variables, and the t-test was used for continuous variables to correlate differences in demographic and clinical factors before and during the pandemic.

RESULTS

The total number of new treatment starts were similar between the pre-pandemic (2,218 patients) and post-pandemic (2,130 patients) periods, but there was a 26% decrease in treatments in April 2020 compared to April 2019 and a 40% increase in treatments in November 2020 compared to November 2019. Post-pandemic patients had higher minimum Charlson Comorbidity Index scores (mean 46.0 vs 42.6, P = 0.0013) and were younger (62.8 yo vs 64.3 yo, P = 0.0001). The proportion of patients being treated from the same state as our institution was higher in the post-pandemic period compared to pre-pandemic (77.8% vs 72.43%, P = 0.0259). Distribution of treatments across department disease-site sections were significantly different (P<0.0001), with the proportion of patients treated by the Breast service having increased by 22% whereas the metropolitan area regional satellites experienced a 18% reduction. There were no statistically significant differences amongst pre- and post-pandemic patients with respect to race, marital status, or smoking status. Post-pandemic patients had less total radiation-related clinical visits (mean 24.8 vs 28.6, P<0.0001), lower administered dose (4329 cGy vs 4533 cGy, P<0.0001), and lower radiation fraction count (17 vs 19, P<0.0001). There was no statistically significant difference in the duration between CT simulation and treatment start, but post-pandemic patients had shorter duration of elapsed days during treatment (27 days vs 29 days, P = 0.0001). A disease-site-specific analysis demonstrated that these differences were most pronounced in patients treated for breast cancer.

CONCLUSION

In the first year of the COVID19 pandemic, our institution saw a dynamic change in the number of new radiation treatments. Additional analyses across individual disease-specific services may reveal insight into dose, fractionation, and technique, which may account for the observed differences.

[Untargeted metabolomics study of dexamethasone-induced congenital cleft palate in New Zealand rabbits]

Objective: To investigate the metabolic disorders in placental tissues of dexamethasone induced cleft palate mode. Methods: Twelve pregnant rabbits were randomly divided into dexamethasone group (experimental group, 8) and saline control group (4), and a certain amount of dexamethasone and saline were administered intramuscularly to the experimental and control groups respectively from embryonic days (ED) 13 to 16, and placental tissue samples were collected on day 21 of gestation. The corresponding profiles of the embryonic placental tissue samples were obtained by liquid chromatography-triple tandem quadrupole(LC-MS), and the metabolites of the embryonic placental tissues were characterized by principal component analysis among the dexamethasone-treated group with cleft palate (D-CP group), the dexamethasone-treated group without cleft palate (D-NCP group) and the control group. Results: There were significant metabolic differences among the D-CP group, D-NCP group and control group, with a total of 133 differential metabolites (VIP>1, P<0.05) involving in important metabolic pathways including vitamin B6 metabolism, lysine metabolism, arginine anabolic metabolism, and galactose metabolism. The four metabolites, vitamin B6, galactose, lysine and urea, differed among the three groups (P<0.05). There were significant differences in vitamin B6 (0.960±0.249, 0.856±0.368, 1.319±0.322), galactose (0.888±0.171, 1.033±0.182, 1.127±0.127), lysine (1.551±0.924, 1.789±1.435, 0.541±0.424) and urea (0.743±0.142, 1.137±0.301, 1.171±0.457, respectively) levels among control group, D-NCP group and D-CP group (F=5.90, P=0.008; F=5.59, P=0.009; F=4.26, P=0.025; F=5.29, P=0.012). Conclusions: The results indicated that dexamethasone induced cleft palate may be highly correlated with metabolic disorders including vitamin B6 metabolism, lysine metabolism, arginine anabolic metabolism and galactose metabolism.

Impact of Treatment Modality on Quality of Life Among Uterine Cancer Survivors

AIMS

Our understanding of the impact of adjuvant therapy on longitudinal quality of life (QoL) following surgery for patients with uterine cancer is limited. The purpose of this study was to compare QoL in patients who have undergone surgery with or without radiation therapy for uterine cancer.

MATERIALS AND METHODS

This was a cross-sectional cohort study that examined women treated for uterine cancer at MD Anderson Cancer Center from 2006 to 2017. Participants included those who underwent hysterectomy/bilateral salphingo-oophorectomy alone, with brachytherapy or external beam radiation therapy (EBRT). A non-cancer cohort of women who underwent a hysterectomy/bilateral salphingo-oophorectomy for benign indications was also identified (non-CA). To compare QoL we used the Functional Assessment of Cancer Therapy - Endometrial survey (FACT-En), a validated survey used to assess QoL. The survey has five subscales: physical, social, emotional, functional and an endometrial cancer-specific subscale. Cohorts were compared using ANOVA tests.

RESULTS

In total, 309 women responded to the questionnaire (hysterectomy/bilateral salphingo-oophorectomy 64, brachytherapy 77, EBRT 96, non-CA 72). The median time from surgery to survey completion was 6.7 years. The mean total FACT-En score for the entire cohort was 144 [standard deviation 22]. Overall QoL was different between cohorts, with the EBRT cohort reporting the lowest QoL (mean 139.4 [21.6]) and the brachytherapy cohort the highest (150.6 [18.2], P = 0.006). Among patients who had undergone cancer treatment, the EBRT cohort reported the worst endometrial-specific QoL (53.5 [8.6]), while again the brachytherapy group reported the highest score (57.5 [6.1], P = 0.007).

CONCLUSIONS

QoL differences in women who have undergone different treatments for uterine cancer may persist years after treatment. In women with endometrial cancer who require adjuvant therapy, brachytherapy does not appear to have any long-term detriments on QoL.

[The study of mitochondrial disorder pedigree associated with FASTKD2 variants and uniparental disomy]

Objective: To analyse the genetic cause of a proband with mitochondrial disease caused by FASTKD2 gene variation and uniparental disomy. Methods: Detailed medical history of a child suspected "mitochondrial disease" were inquired in Peking University First Hospital on November 23, 2017. c.810_820dup homozygous variation in FASTKD2 gene was found by high-throughput sequencing, and her mother had heterozygous variation, but her father didn't have such variation, which didn't conform to the genetic law of variation. Further clinical examinations and molecular genetic tests were carried out. The venous blood of the child and her parents was drawn, and genomic DNA was extracted. Sanger sequencing, polymerase chain reaction (PCR) testing, short tandem repeat (STR) analysis, chromosome microarray analysis and loss of heterozygosity (LOH) genetic relationship analysis were performed on the proband and the parents to determine the variation. Results: The clinical manifestations, physical examination and laboratory examination of the child supported the diagnosis of mitochondrial disease. c.810_820dup(p.Ser274Phefs*8) homozygous variant in FASTKD2 gene was identified. Sanger sequencing indicated that the mother was a heterozygote of the variant, while the father had no such variation, which did not conform to the genetic law. PCR testing and Sanger sequencing review to eliminate sampling errors, PCR amplification and sequencing errors. Non-biological father was excluded by STR analysis. Three large segmental LOH of FASTKD2 gene were found by chromosome microarray analysis, then the LOH relative analysis verified the child was a mixed maternal uniparental disomy of chromosome 2. The child was diagnosed as mitochondrial disease caused by oxidative phosphorylation coupling defect of type 44. Conclusions: In this study, an autosomal recessive mitochondrial disease which does not conform to the genetic law was found, and it was confirmed that this mitochondrial disease family had both pathogenic variation and uniparental disomy phenomenon. It was diagnosed as mitochondrial disease caused by type 44 oxidative phosphorylation coupling defect.

[Occurrence of live-born twins with birth weight-discordance and its relationship to the adverse birth outcomes]

Objective: To investigate the occurrence of live-born twins with birth weight-discordance and its relationship to adverse birth outcomes. Methods: A retrospective analysis was performed on 4 011 pairs of live-born twins in the Third Affiliated Hospital of Guangzhou Medical University from January 2011 to December 2020. Based on the birth-weight discordance (∆BW, ∆BW=(birth-weight_big-birth-weight_small)/birth-weight_big×100%)), twins were divided into 4 groups, including ∆BW≤15%,>15%-20%,>20%-25%, and>25%. The differences in maternal and neonatal outcomes among 4 groups were explored. Then the correlation between ∆BW and neonatal adverse outcomes were explored. Results: The ΔBW was 9 (4, 16)% and males were accounted for 53.8% (4 315 cases) of 4 011 pairs of twins. The gestational age was (35.3±2.7) weeks at birth. There were 2 908 pairs (72.5%) of twins with ΔBW≤15%, 481 pairs (12.0%) with ΔBW>15%-20%, 281 pairs (7.0%) with ΔBW 20%-≤25%, and 341 twin pairs (8.5%) with ΔBW>25%. With ∆BW of 20% as the diagnostic cutoff, the incidence of birth weight discordance was 15.5% (622/4 011). The proportion of natural births in the ∆BW≤15% group was higher than that in the ∆BW>15%-20% group (10.5% (288/2 740) vs. 6.3% (29/463), P<0.008 3). The ∆BW>25% group had a significantly higher prevalence of maternal hypertensive disorders during pregnancy than that of the other 3 groups (25.5% (87/341) vs. 16.7% (47/281) vs.17.3% (83/480) vs. 13.8% (400/2 899), all P<0.008 3). Univariate analysis found that the ΔBW>25% group had a lower gestational age and a higher rate of preterm birth than the other groups. The rate of extremely low birth weight (ELBW) or very low birth weight (VLBW), small for gestational age (SGA), and transferring to the department of neonatology in the smaller twins were significantly different among the 4 groups (all P<0.05). Multivariate analysis showed that higher degree of birth weight discordance was all positively associated with the rate of ELBW, SGA, and transferring to the department of neonatology in smaller twin, even after adjusting maternal age and gestational hypertension, year of birth, mode of delivery, gender, and gestational age (all P<0.05). Moreover, the Mantel-Haenszel test also indicated that there were significantly low to moderate correlations between ΔBW and the unfavorable outcomes (r=0.22, 0.53, 0.21, all P<0.001, respectively). The receiver operating characteristic (ROC) curve found that adverse birth outcomes would be well predicted by birth weight-discordant when the diagnostic cut-off of ΔBW was 12%-17%, with an acceptable sensitivity (0.53-0.78) and a high specificity (0.72-0.79). Conclusions: Birth weight discordant is not uncommon in live-born twins, and is associated with adverse outcomes including ELBW, SGA, and transferring to the department of neonatology in the small twins. Besides, the risk is linearly related to the increase of ΔBW. In the future, more researches are needed to explore the underline mechanism and long-term impact of birth weight discordance, to guide the prevention and management.

Activation and thermal stabilization of a recombinant γ-glutamyltranspeptidase from Bacillus licheniformis ATCC 27811 by monovalent cations

The regulation of enzyme activity through complexation with certain metal ions plays an important role in many biological processes. In addition to divalent metals, monovalent cations (MVCs) frequently function as promoters for efficient biocatalysis. Here, we examined the effect of MVCs on the enzymatic catalysis of a recombinant γ-glutamyltranspeptidase (BlrGGT) from Bacillus licheniformis ATCC 27,811 and the application of a metal-activated enzyme to L-theanine synthesis. The transpeptidase activity of BlrGGT was enhanced by Cs⁺ and Na⁺ over a broad range of concentrations with a maximum of 200 mM. The activation was essentially independent of the ionic radius, but K⁺ contributed the least to enhancing the catalytic efficiency. The secondary structure of BlrGGT remained mostly unchanged in the presence of different concentrations of MVCs, but there was a significant change in its tertiary structure under the same conditions. Compared with the control, the half-life (t_1/2) of the Cs⁺-enriched enzyme at 60 and 65 °C was shown to increase from 16.3 and 4.0 min to 74.5 and 14.3 min, respectively. The simultaneous addition of Cs⁺ and Mg²⁺ ions exerted a synergistic effect on the activation of BlrGGT. This was adequately reflected by an improvement in the conversion of substrates to L-theanine by 3.3-15.1% upon the addition of 200 mM MgCl₂ into a reaction mixture comprising the freshly desalted enzyme (25 μg/mL), 250 mM L-glutamine, 600 mM ethylamine, 200 mM each of the MVCs, and 50 mM borate buffer (pH 10.5). Taken together, our results provide interesting insights into the complexation of MVCs with BlrGGT and can therefore be potentially useful to the biocatalytic production of naturally occurring γ-glutamyl compounds. KEY POINTS: • The transpeptidase activity of B. licheniformis γ-glutamyltranspeptidase can be activated by monovalent cations. • The thermal stability of the enzyme was profoundly increased in the presence of 200 mM Cs⁺. • The simultaneous addition of Cs⁺and Mg²⁺ions to the reaction mixture improves L-theanine production.

[Analysis of risk factors for gestational diabetes mellitus in elderly multipara women in the next pregnancy]

Objective: To investigate the risk factors for gestational diabetes mellitus (GDM) in elderly multipara women in the next pregnancy. Methods: A total of 219 elderly multipara women with 2 consecutive delivery records in Tianjin Binhai New Area Tanggu Obstetrics and Gynecology Hospital from January 2018 to May 2019 were included. Among them, 141 had normal glucose tolerance (NGT) and 78 of them had GDM. The clinical data of the previous and current pregnancy were collected to analyze the risk factors of GDM in elderly multipara women. Results: The average ages of 219 elderly women in previous pregnancy and this pregnancy were (31.9±2.2) and (36.7±1.5) years old, and the prevalence of GDM was 35.62% (78 cases). Compared to NGT group, GDM patients had higher fasting blood glucose(previous (5.51±1.43) vs (4.63±0.62) mmol/L; current (5.26±0.63) vs (4.59±0.30) mmol/L, 1 h blood glucose(previous (11.74±2.36) vs (9.50±1.82) mmol/L; current (11.03±2.03) vs (9.51±1.14) mmol/L) in 75 g oral glucose tolerance test (OGTT) in both previous and current pregnancy. The rates of cesarean section, in both previous and current pregnancy were higher in GDM group (previous 34.6% vs 4.3%; current 52.6% vs 22.0%). Furthermore, prenatal weight and body mass index (BMI) of the previous pregnancy, pre-pregnancy weight and BMI, and prenatal BMI of this pregnancy were also higher in GDM group, and the differences were all statistically significant (all P<0.05). Logistic multivariate regression analysis indicated cesarean section history (OR=10.80, 95%CI: (4.09-28.54)), GDM history of previous pregnancy (OR=10.64, 95%CI: (4.02-28.20)), 75 g OGTT fasting blood glucose≥ 4.86 mmol/L (OR=2.70, 95%CI: (1.27-5.70)), 1 h blood glucose after glucose administration ≥ 8.45 mmol/L (OR=1.78, 95%CI: (1.37-2.31)) were risk factors for GDM in elderly multipara women of this pregnancy. Conclusion: The risk of GDM in elderly multipara women with a history of cesarean section and GDM increases significantly. Results of OGTT in previous pregnancy also has predictive value.

Affinity Immobilization of a Bacterial Prolidase onto Metal-Ion-Chelated Magnetic Nanoparticles for the Hydrolysis of Organophosphorus Compounds

In this study, silica-coated magnetic nanoparticles (SiMNPs) with isocyanatopropyltriethoxysilane as a metal-chelating ligand were prepared for the immobilization of His6-tagged Escherichia coli prolidase (His6-EcPepQ). Under one-hour coupling, the enzyme-loading capacity for the Ni2+-functionalized SiMNPs (NiNTASiMNPs) was 1.5 mg/mg support, corresponding to about 58.6% recovery of the initial activity. Native and enzyme-bound NiNTASiMNPs were subsequently characterized by transmission electron microscopy (TEM), superparamagnetic analysis, X-ray diffraction, and Fourier transform infrared (FTIR) spectroscopy. As compared to free enzyme, His6-EcPepQ@NiNTASiMNPs had significantly higher activity at 70 °C and pH ranges of 5.5 to 10, and exhibited a greater stability during a storage period of 60 days and could be recycled 20 times with approximately 80% retention of the initial activity. The immobilized enzyme was further applied in the hydrolysis of two different organophosphorus compounds, dimethyl p-nitrophenyl phosphate (methyl paraoxon) and diethyl p-nitrophenyl phosphate (ethyl paraoxon). The experimental results showed that methyl paraoxon was a preferred substrate for His6-EcPepQ and the kinetic behavior of free and immobilized enzymes towards this substance was obviously different. Taken together, the immobilization strategy surely provides an efficient means to deposit active enzymes onto NiNTASiMNPs for His6-EcPepQ-mediated biocatalysis.

High-level expression and molecular characterization of a recombinant prolidase from Escherichia coli NovaBlue

Long-term use of organophosphorus (OP) compounds has become an increasing global problem and a major threat to sustainability and human health. Prolidase is a proline-specific metallopeptidase that can offer an efficient option for the degradation of OP compounds. In this study, a full-length gene from Escherichia coli NovaBlue encoding a prolidase (EcPepQ) was amplified and cloned into the commercially-available vector pQE-30 to yield pQE-EcPepQ. The overexpressed enzyme was purified from the cell-free extract of isopropyl thio-β-D-galactoside IPTG-induced E. coli M15 (pQE-EcPepQ) cells by nickel-chelate chromatography. The molecular mass of EcPepQ was determined to be about 57 kDa by 12% sodium dodecyl sulfate–polyacrylamide gel electrophoresis and the result of size-exclusion chromatography demonstrated that the enzyme was mainly present in 25 mM Tris–HCl buffer (pH 8.0) as a dimeric form. The optimal conditions for EcPepQ activity were 60 °C, pH 8.0, and 0.1 mM Mn²⁺ ion. Kinetic analysis with Ala-Pro as the substrate showed that the K_m and k_cat values of EcPepQ were 8.8 mM and 926.5 ± 2.0 s⁻¹, respectively. The thermal unfolding of EcPepQ followed a two-state process with one well-defined unfolding transition of 64.2 °C. Analysis of guanidine hydrochloride (GdnHCl)-induced denaturation by tryptophan emission fluorescence spectroscopy revealed that the enzyme had a [GdnHCl]_0.5,N-U value of 1.98 M. The purified enzyme also exhibited some degree of tolerance to various water/organic co-solvents. Isopropanol and tetrahydrofuran were very detrimental to the enzymatic activity of EcPepQ; however, other more hydrophilic co-solvents, such as formamide, methanol, and ethylene glycol, were better tolerated. Eventually, the non-negative influence of some co-solvents on both catalytic activity and structural stability of EcPepQ allows to adjust the reaction conditions more suitable for EcPepQ-catalyzed bioprocess.

Protective Effect of Biological Osmolytes against Heat- and Chaotropic Agent-Induced Denaturation of Bacillus licheniformis γ-Glutamyl Transpeptidase

In the present study, the stabilizing effect of four different biological osmolytes on Bacillus licheniformis γ-glutamyl transpeptidase (BlGGT) was investigated. BlGGT appeared to be stable under temperatures below 40°C, but the enzyme retained less than 10% of its activity at 60°C. The tested osmolytes exhibited different degrees of effectiveness against temperature inactivation of BlGGT, and sucrose was found to be the most effective among these. The use of circular dichroism spectroscopy for studying the secondary structure of BlGGT revealed that the temperature-induced conformational change of the protein molecule could be prevented by the osmolytes. Consistently, the molecular structure of the enzyme was essentially conserved by the osmolytes at elevated temperatures as monitored by fluorescence spectroscopy. Sucrose was further observed to counteract guanidine hydrochloride (GdnHCl)- and urea-induced denaturation of BlGGT. Taken together, we observed evidently that some well-known biological osmolytes, especially sucrose, make a dominant contribution to the structural stabilization of BlGTT.

[Distributions and associations between duration of sleep, daytime naps and insomnia symptoms among Chinese adults]

Objective: To investigate the distribution of sleep duration, daytime naps habits, and insomnia-related symptoms among participants from the China Kadoorie Biobank (CKB) study, and to examine the associations between the sleep-associated factors. Methods: A self-designed computer-based questionnaire was adopted to collect social-demographic information and lifestyle-related factors of the participants. A total of 452 829 Chinese adults aged 30-79 years, without self-reported histories of coronary heart disease, stroke, chronic obstructive pulmonary diseases or cancer, were included in this study. General linear regression and multinomial logistic regression models were used to estimate the distributions on duration of sleep, daytime naps habits, and insomnia-related symptoms in different populations, after adjusted for gender, age, and residential regions. Gender-specific logistic regression model was adopted to examine the associations between the above mentioned sleep-related factors. Results: The average sleep duration of the participants was 7.41 hours per day, with 20.3% of them having daytime naps all year round, but 40.1% only had daytime naps in summer, and 39.6% had no habits of daytime naps. 11.0%, 10.0%, and 2.1% of the participants reported having had symptoms as difficulty in falling asleep, waking up too early or with daytime dysfunction, respectively. There were significant differences on the distributions in sleep-related factors between participants with different gender, age, residential areas, education levels,household income, and marital status (P<0.05). Results from the logistic regression showed that longer sleep duration was associated with lower risks of insomnia-related symptoms trend (P<0.001). Factor as without habits of daytime naps seemed to be associated with higher risks of insomnia-related symptoms (P<0.05). Participants with longer sleep duration were more likely to have the habit of taking daytime naps (P<0.05). Conclusions: The distributions of sleep duration, habits on daytime naps and insomnia-related symptoms varied according to the differences on social-demographic factors. There were associations existed between the sleeping-related factors, which would influence the promotion on optimal sleep duration and better quality of sleep.

[Present situation and analysis of murine allergic rhinitis model]

There have been 20 years of history in the study of allergic rhinitis(AR) using a mice model. At present, the AR mice model still exists some problems in the selection of mice strains, allergens and adjuvant types, molding cycle, allergen dose, model judgment, and so on, which affects the authenticity and comparability of the research results. By gradually solving the problems existing in the mice AR model, it is of great significance to realize the standardization of AR model, and the depth of the AR research.

[Effect of specific immunotherapy on the psychological health level and quality of life in patients with allergic rhinitis]

Objective: To study the effect of specific immunotherapy on the psychological health level and quality of life in patients with allergic rhinitis(AR).Method:Selected 97 cases diagnosed as moderate to severe persistent AR patients, were treated with specific immunotherapy for one year. All patients received the evaluation with symptom check list 90(SCL-90) and rhinoconjunctivitis quality of life questionnaire(RQLQ) before specific immunotherapy, six, and 12 months after specific immunotherapy.Result:The total scores, scores of somatization, obsessive, anxiety, depression and phobia in SCL-90 of AR patients after 12 months treatment were significantly lower than that before treatment（P < 0.05）. Total score of quality of life and subitem score in RQLQ of AR patients after 12 months treatment were obviously lower than that before treatment (P < 0.05）.Conclusion:Specific immunotherapy can effectively alleviate the clinical symptoms and improve psychological health level and quality of life of AR patients.

Taxonomic Study of the Genus Apalacris Walker (Orthoptera: Catantopidae)

The research history of the genus Apalacris is reviewed; a key to all known species of the genus is given, and one new species, Apalacris eminifronta n. sp., and one new combination, Apalacris maculifemura (Lin & Zheng), are described. The new species is very closely related to Apalacris antennata Liang, but differs in the following characters: (1) tegmen longer, reaching apex of hind femur; (2) basal part of inner side of hind femur orange red; (3) frontal ridge more protruded, obviously depressed under median ocellus in lateral view; and (4) epiphallus bridge prominent, ancora shorter than anterior projection.

Bacillus licheniformistrehalose-6-phosphate hydrolase structures suggest keys to substrate specificity

Trehalose-6-phosphate hydrolase (TreA) belongs to glycoside hydrolase family 13 (GH13) and catalyzes the hydrolysis of trehalose 6-phosphate (T6P) to yield glucose and glucose 6-phosphate. The products of this reaction can be further metabolized by the energy-generating glycolytic pathway. Here, crystal structures ofBacillus licheniformisTreA (BlTreA) and its R201Q mutant complexed withp-nitrophenyl-α-D-glucopyranoside (R201Q–pPNG) are presented at 2.0 and 2.05 Å resolution, respectively. The overall structure ofBlTreA is similar to those of other GH13 family enzymes. However, detailed structural comparisons revealed that the catalytic site ofBlTreA contains a long loop that adopts a different conformation from those of other GH13 family members. Unlike the homologous regions ofBacillus cereusoligo-1,6-glucosidase (BcOgl) andErwinia rhaponticiisomaltulose synthase (NX-5), the surface potential of theBlTreA active site exhibits a largely positive charge contributed by the four basic residues His281, His282, Lys284 and Lys292. Mutation of these residues resulted in significant decreases in the enzymatic activity ofBlTreA. Strikingly, the281HHLK284motif and Lys292 play critical roles in substrate discrimination byBlTreA.

Gene expression and molecular characterization of a chaperone protein HtpG from Bacillus licheniformis

Heat shock protein 90 (Hsp90/HtpG) is a highly abundant and ubiquitous ATP-dependent molecular chaperone consisting of three flexibly linked regions, an N-terminal nucleotide-binding domain, middle domain, and a C-terminal domain. Here the putative htpG gene of Bacillus licheniformis was cloned and heterologously expressed in Escherichia coli M15 cells. Native-gel electrophoresis, size exclusion chromatography, and cross-linking analysis revealed that the recombinant protein probably exists as a mixture of monomer, dimer and other oligomers in solution. The optimal conditions for the ATPase activity of B. licheniformis HtpG (BlHtpG) were 45°C and pH 7.0 in the presence of 0.5mM Mg(2+) ions. The molecular architecture of this protein was stable at higher temperatures with a transition point (Tm) of 45°C at neutral pH, whereas the Tm value was reduced to 40.8°C at pH 10.5. Acrylamide quenching experiment further indicated that the dynamic quenching constant (Ksv) of BlHtpG became larger at higher pH values. BlHtpG also experienced a significant change in the protein conformation upon the addition of ATP and organic solvents. Collectively, our experiment data may provide insights into the molecular properties of BlHtpG and identify the alteration of protein structure to forfeit the ATPase activity at alkaline conditions.

Immunomodulatory Potential of the Polysaccharide-Rich Extract from Edible Cyanobacterium Nostoc commune

A dry sample of Nostoc commune from an organic farm in Pingtung city (Taiwan) was used to prepare polysaccharide-rich (NCPS) extract. The conditioned medium (CM) from NCPS-treated human peripheral blood (PB)-mononuclear cells (MNC) effectively inhibited the growth of human leukemic U937 cells and triggered differentiation of U937 monoblast cells into monocytic/macrophagic lines. Cytokine levels in MNC-CMs showed upregulation of granulocyte/macrophage-colony stimulatory factor and IL-1β and downregulation of IL-6 and IL-17 upon treatment with NCPS. Moreover, murine macrophage RAW264.7 cells treated with NCPS exhibited the stimulatory effects of nitric oxide and superoxide secretion, indicating that NCPS might activate the immunity of macrophages. Collectively, the present study demonstrates that NCPS from N. commune could be potentially used for macrophage activation and consequently inhibited the leukemic cell growth and induced monocytic/macrophagic differentiation.

The maturation mechanism of γ-glutamyl transpeptidases: Insights from the crystal structure of a precursor mimic of the enzyme from Bacillus licheniformis and from site-directed mutagenesis studies

γ-Glutamyl transpeptidases (γ-GTs) are members of N-terminal nucleophile hydrolase superfamily. They are synthetized as single-chain precursors, which are then cleaved to form mature enzymes. Basic aspects of autocatalytic processing of these pro-enzymes are still unknown. Here we describe the X-ray structure of the precursor mimic of Bacillus licheniformis γ-GT (BlGT), obtained by mutating catalytically important threonine to alanine (T399A-BlGT), and report results of autoprocessing of mutants of His401, Thr415, Thr417, Glu419 and Arg571. Data suggest that Thr417 is in a competent position to activate the catalytic threonine (Thr399) for nucleophilic attack of the scissile peptide bond and that Thr415 plays a major role in assisting the process. On the basis of these new structural results, a possible mechanism of autoprocessing is proposed. This mechanism, which guesses the existence of a six-membered transition state involving one carbonyl and two hydroxyl groups, is in agreement with all the available experimental data collected on γ-GTs from different species and with our new Ala-scanning mutagenesis data.

Two New Species of the Genus Criotettix Bolivar (Orthoptera: Tetrigidae), with a Key to the Species of the Genus from China

Two new species of the tetrigid genus Criotettix Bolivar from China, namely Criotettix interruptaoides Deng & Zheng n. sp. and Criotettix shiwanshanensis Deng & Zheng n. sp. are described. An updated key to all known species of the genus from China is given.

Description of a New Species of the Genus Macromotettixoides Zheng (Orthoptera: Tetrigoidea: Metrodorinae) from China

A new species, Macromotettixoides lativertex Deng et al n. sp. is described with detailed illustrations of external morphology. Comparison between the species M. lativertex n. sp. and allied species is compiled into a table for identification. The distribution and an updated identification key to all known species of the genus is given.

A Review of the Genus Pielomastax Chang (Orthoptera: Eumastacoidea) from China with Description of a New Species

The review of the genus Pielomastax is given. The genus consists of 14 species distributed in China. Pielomastax cladopygidium n. sp. is described from Shaanxi Province. An annotated list of species and key to species of Pielomastax is provided.

Surface-functionalized hyperbranched poly(amido acid) magnetic nanocarriers for covalent immobilization of a bacterial γ-glutamyltranspeptidase

In this study, we synthesized water-soluble hyperbranched poly(amido acid)s (HBPAAs) featuring multiple terminal CO₂H units and internal tertiary amino and amido moieties and then used them in conjunction with an in situ Fe^2+/Fe³⁺ co-precipitation process to prepare organic/magnetic nanocarriers comprising uniformly small magnetic iron oxide nanoparticles (NP) incorporated within the globular HBPAAs. Transmission electron microscopy revealed that the HBPAA-γ-Fe₂O₃ NPs had dimensions of 6–11 nm, significantly smaller than those of the pristine γ-Fe₂O₃ (20–30 nm). Subsequently, we covalently immobilized a bacterial γ-glutamyltranspeptidase (BlGGT) upon the HBPAA-γ-Fe₂O₃ nanocarriers through the formation of amide linkages in the presence of a coupling agent. Magnetization curves of the HBPAA-γ-Fe₂O₃/BlGGT composites measured at 300 K suggested superparamagnetic characteristics, with a saturation magnetization of 52 emu g⁻¹. The loading capacity of BlGGT on the HBPAA-γ-Fe₂O₃ nanocarriers was 16 mg g⁻¹ support; this sample provided a 48% recovery of the initial activity. The immobilized enzyme could be recycled 10 times with 32% retention of the initial activity; it had stability comparable with that of the free enzyme during a storage period of 63 days. The covalent immobilization and stability of the enzyme and the magnetization provided by the HBPAA-γ-Fe₂O₃ NPs suggests that this approach could be an economical means of depositing bioactive enzymes upon nanocarriers for BlGGT-mediated bio-catalysis.

Biophysical characterization of a recombinant aminopeptidase II from the thermophilic bacterium Bacillus stearothermophilus

In the present study, the biophysical properties of His6-tagged Bacillus stearothermophilus aminopeptidase II (His6-tagged BsAmpII) are characterized in detail by gel-filtration, analytical ultracentrifugation, and various spectroscopic techniques. Using size-exclusion chromatography and analytical ultracentrifugation, we demonstrate that His6-tagged BsAmpII exists predominantly as a dimer in solution. The enzyme is active and stable at pHs ranging from 6.5 to 8.5. Far-UV circular dichroism analysis reveals that the secondary structures of His6-tagged BsAmpII are significantly altered in the presence of SDS, whereas the presence of 5-10% acetone and ethanol was harmless to the folding of the enzyme. Thermal unfolding of His6-tagged BsAmpII was found to be irreversible and led to the formation of aggregates. The native enzyme started to unfold beyond 0.6 M guanidine hydrochloride and had a midpoint of denaturation at 1.34 M. This protein remained active at concentrations of urea below 2.7 M but experienced an irreversible unfolding by >5 M denaturant. Taken together, this work lays a foundation for potential biotechnological applications of His6-tagged BsAmpII.

Characterization of glycine substitution mutations within the putative NAD+-binding site of Bacillus licheniformis aldehyde dehydrogenase

The NAD(+)-requiring enzymes of the aldehyde dehydrogenase (ALDH) family contain a glycine motif, GX1- 2GXXG, which is reminiscent of the fingerprint region of the Rossman fold, a conserved structural motif of the classical nicotinamide nucleotide-binding proteins. In this research, the role of three glycine residues situated within the putative NAD(+)-binding motif (211-GPGSSAG) together with Gly233 and Gly238 of Bacillus licheniformis ALDH (BlALDH) were probed by site-directed mutatgenesis. Fifteen mutant BlALDHs were obtained by substitution of the indicated glycine residues with alanine, glutamate and arginine. Except for the Ala replacement at positions 211, 213, 217 and 238, the remaining mutant enzymes lost the dehydrogenase activity completely. Tryptophan fluorescence and far-UV circular dichroism spectra allowed us to discriminate BlALDH and the inactive mutant enzymes, and unfolding analyses further revealed that they had a different sensitivity towards temperature- and guanidine hydrochloride (GdnHCl)-induced denaturation. BlALDH and the functional variants had a comparable T(m) value, but the value was reduced by more than 5.1°C in the rest of mutant enzymes. Acrylamide quenching analysis showed that the inactive mutant enzymes had a dynamic quenching constant greater than that of BlALDH. Native BlALDH started to unfold beyond ~0.21 M GdnHCl and reached an unfolded intermediate, [GdnHCl](0.5, N-U), at 0.92 M equivalent to free energy change (ΔG(N-U)(H2O)) of 12.34 kcal/mol for the N → U process, whereas the denaturation midpoints for mutant enzymes were 0.45-1.61 M equivalent to ΔG(N-U)(H2O) of 0.31-4.35 kcal/mol. Taken together, these results strongly suggest that the explored glycines are indeed important for the catalytic activity and structural stability of BlALDH.

Covalent Immobilization of Bacillus licheniformis γ-Glutamyl Transpeptidase on Aldehyde-Functionalized Magnetic Nanoparticles

This work presents the synthesis and use of surface-modified iron oxide nanoparticles for the covalent immobilization of Bacillus licheniformis γ-glutamyl transpeptidase (BlGGT). Magnetic nanoparticles were prepared by an alkaline solution of divalent and trivalent iron ions, and they were subsequently treated with 3-aminopropyltriethoxysilane (APES) to obtain the aminosilane-coated nanoparticles. The functional group on the particle surface and the amino group of BlGGT was then cross-linked using glutaraldehyde as the coupling reagent. The loading capacity of the prepared nanoparticles for BlGGT was 34.2 mg/g support, corresponding to 52.4% recovery of the initial activity. Monographs of transmission electron microscopy revealed that the synthesized nanoparticles had a mean diameter of 15.1 ± 3.7 nm, and the covalent cross-linking of the enzyme did not significantly change their particle size. Fourier transform infrared spectroscopy confirmed the immobilization of BlGGT on the magnetic nanoparticles. The chemical and kinetic behaviors of immobilized BlGGT are mostly consistent with those of the free enzyme. The immobilized enzyme could be recycled ten times with 36.2% retention of the initial activity and had a comparable stability respective to free enzyme during the storage period of 30 days. Collectively, the straightforward synthesis of aldehyde-functionalized nanoparticles and the efficiency of enzyme immobilization offer wide perspectives for the practical use of surface-bound BlGGT.

Experimental evidence for the involvement of amino acid residue Glu398 in the autocatalytic processing of Bacillus licheniformis γ-glutamyltranspeptidase

The role of glutamate 398 in the autocatalytic processing of Bacillus licheniformis γ-glutamyltranspeptidase (BlGGT) was explored by site-directed mutagenesis. This glutamate was substituted by either alanine, aspartate, arginine or glutamine and the expressed mutant enzymes were purified to apparent homogeneity with metal-affinity chromatography. SDS–PAGE analysis showed that E398A, E398D and E398K were unable to process themselves into a large and a small subunit. However, E398Q was not only able to process itself, but also had a catalytic activity comparable to that of BlGGT. As compared with the wild-type enzyme, no significant change in circular dichroism spectra was observed for the mutant proteins. Thermal unfolding of BlGGT, E398A, E398D, E398K and E398Q followed the two-state unfolding process with a transition point (T_m) of 47.7–69.4 °C. Tryptophan fluorescence spectra of the mutant enzymes were different from the wild-type protein in terms of fluorescence intensity. Native BlGGT started to unfold beyond ∼1.92 M guanidine hydrochloride (GdnHCl) and reached an unfolded intermediate, [GdnHCl]_{0.5, N–U}, at 3.07 M equivalent to free energy change (Δ⁢GN−UH2⁢O) of 14.53 kcal/mol for the N → U process, whereas the denaturation midpoints for the mutant enzymes were 1.31–2.99 M equivalent to Δ⁢GN−UH2⁢O of 3.29–12.05 kcal/mol. Taken together, these results strongly suggest that the explored glutamate residue is indeed important for the autocatalytic processing of BlGGT.

Contribution of conserved Glu255 and Cys289 residues to catalytic activity of recombinant aldehyde dehydrogenase from Bacillus licheniformis

Based on the sequence homology, we have modeled the three-dimensional structure of Bacillus licheniformis aldehyde dehydrogenase (BlALDH) and identified two different residues, Glu255 and Cys289, that might be responsible for the catalytic function of the enzyme. The role of these residues was further investigated by site-directed mutagenesis and biophysical analysis. The expressed parental and mutant proteins were purified by nickel-chelate chromatography, and their molecular masses were determined to be approximately 53 kDa by SDS-PAGE. As compared with the parental BlALDH, a dramatic decrease or even complete loss of the dehydrogenase activity was observed for the mutant enzymes. Structural analysis showed that the intrinsic fluorescence and circular dichroism spectra of the mutant proteins were similar to the parental enzyme, but most of the variants exhibited a different sensitivity towards thermal- and guanidine hydrochloride-induced denaturation. These observations indicate that residues Glu255 and Cys289 play an important role in the dehydrogenase activity of BlALDH, and the rigidity of the enzyme has been changed as a consequence of the mutations.

Biophysical studies of an NAD(P)(+)-dependent aldehyde dehydrogenase from Bacillus licheniformis

Aldehyde dehydrogenase (ALDH) catalyzes the conversion of aldehydes to the corresponding acids by means of an NAD(P)(+)-dependent virtually irreversible reaction. In this investigation, the biophysical properties of a recombinant Bacillus licheniformis ALDH (BlALDH) were characterized in detail by analytical ultracentrifuge (AUC) and various spectroscopic techniques. The oligomeric state of BlALDH in solution was determined to be tetrameric by AUC. Far-UV circular dichroism analysis revealed that the secondary structures of BlALDH were not altered in the presence of acetone and ethanol, whereas SDS had a detrimental effect on the folding of the enzyme. Thermal unfolding of this enzyme was found to be highly irreversible. The native enzyme started to unfold beyond ~0.2 M guanidine hydrochloride (GdnHCl) and reached an unfolded intermediate, [GdnHCl](05, N-U), at 0.93 M. BlALDH was active at concentrations of urea below 2 M, but it experienced an irreversible unfolding under 8 M denaturant. Taken together, this study provides a foundation for the future structural investigation of BlALDH, a typical member of ALDH superfamily enzymes.

Unfolding analysis of the mature and unprocessed forms of Bacillus licheniformis γ-glutamyltranspeptidase

Bacillus licheniformis γ-glutamyltranspeptidase (BlGGT) undergoes an autocatalytic process to generate 44.9 and 21.7 kDa subunits; however, a mutant protein (T399A) loses completely the processing ability and mainly exists as a precursor. For a comprehensive understanding of their structural features, the biophysical properties of these two proteins were investigated by circular dichroism and fluorescence spectroscopy. Tryptophan fluorescence and circular dichroism spectra were nearly identical for BlGGT and T399A, but unfolding analyses revealed that these two proteins had a different sensitivity towards temperature- and guanidine hydrochloride (GdnHCl)-induced denaturation. BlGGT and the unprocessed T399A displayed T(m) values of 61.4°C and 68.1°C, respectively, and thermal unfolding of both proteins was found to be highly irreversible. Fluorescence quenching analysis showed that T399A had a dynamic quenching constant similar to that of the wild-type enzyme. BlGGT started to unfold beyond ∼2.14 M GdnHCl and reached an unfolded intermediate, [GdnHCl](0.5, N - U), at 2.85 M, corresponding to free energy change [Formula: see text] of 12.34 kcal mol( - 1), whereas the midpoint of the denaturation curve for T399A was approximately 3.94 M, corresponding to a [Formula: see text] of 4.45 kcal mol( - 1). Taken together, it can be concluded that the structural stability of BlGGT is superior to that of T399A.

Involvement of residues Asp8, Asn13, Glu145, Asp168, and Thr173 in the chaperone activity of a recombinant DnaK from Bacillus licheniformis

Based on the sequence homology, we have modeled the three-dimensional structure of Bacillus licheniformis DnaK (BlDnaK), a counterpart of Hsp70, and identified five different amino acids that might be responsible for maintaining ADP-Mg(2+)-Pi in the correct configuration at the ATP-binding cleft of the protein. As compared with wild-type BlDnaK, site-directed mutant proteins D8A, N13D, E145A, D168A, and T173A had a dramatic reduction in their chaperone activities. Complementation test revealed that the mutant proteins lost completely the ability to rescue the temperature-sensitive growth defect of Escherichia colidnaK756-ts. Wild-type BlDnak assisted the refolding of denatured firefly luciferase, whereas a significant decrease in this ability was observed for the mutant proteins. Simultaneous addition of B. licheniformis DnaJ, BlGrpE, and NR-peptide, did not synergistically stimulate the ATPase activity of D8A, E145A, D168A and T173A. Circular dichroism spectra were nearly identical for wild-type and mutant proteins, and they, except D8A, also exhibited a similar sensitivity towards temperature-induced denaturation. These results suggest that the selected residues are critical for the proper function of BlDnaK.

Biophysical characterization of Bacillus licheniformis and Escherichia coli γ-glutamyltranspeptidases: A comparative analysis

The oligomeric states of Bacillus licheniformis and Escherichia coli γ-glutamyltranspeptidases (BlGGT and EcGGT) in solution have been investigated by analytical ultracentrifugation. The results showed that BlGGT has a sedimentation coefficient of 5.12S, which can be transformed into an experimental molecular mass of approximately 62,680Da. The monomeric conformation is conserved in EcGGT. SDS-PAGE analysis and cross-linking studies further proved that the autocatalytically processed BlGGT and EcGGT form a heterodimeric association. Unfolding analyses using circular dichroism and tryptophan emission fluorescence revealed that these two proteins had a different sensitivity towards temperature- and guanidine hydrochloride (GdnHCl)-induced denaturation. BlGGT and EcGGT had a T(m) value of 59.5 and 49.2°C, respectively, and thermal unfolding of both proteins was found to be highly irreversible. Chemical unfolding of BlGGT was independent to the pH value ranging from 5 to 10, whereas the pH environment was found to significantly influence the GdnHCl-induced denaturation of EcGGT. Both enzymes did not reactivate from the completely unfolded states, accessible at 6M GdnHCl. BlGGT was active in the presence of 4M NaCl, whereas the activity of EcGGT was significantly decreased at the high-salt condition. Taken together, these findings suggest that the biophysical properties of the homologous GGTs from two mesophilic sources are quite different.

Effects of C-terminal truncation on autocatalytic processing of Bacillus licheniformis gamma-glutamyl transpeptidase

The role of the C-terminal region of Bacillus licheniformis gamma-glutamyl transpeptidase (BlGGT) was investigated by deletion analysis. Seven C-terminally truncated BlGGTs lacking 581-585, 577-585, 576-585, 566-585, 558-585, 523-585, and 479-585 amino acids, respectively, were generated by site-directed mutagenesis. Deletion of the last nine amino acids had no appreciable effect on the autocatalytic processing of the enzyme, and the engineered protein was active towards the synthetic substrate L-gamma-glutamyl-p-nitroanilide. However, a further deletion to Val576 impaired the autocatalytic processing. In vitro maturation experiments showed that the truncated BlGGT precursors, pro-Delta(576-585), pro-Delta(566-585), and pro-Delta(558-585), could partially precede a time-dependent autocatalytic process to generate the L- and S-subunits, and these proteins showed a dramatic decrease in catalytic activity with respect to the wild-type enzyme. The parental enzyme (BlGGT-4aa) and BlGGT were unfolded biphasically by guanidine hydrochloride (GdnCl), but Delta(577-585), Delta(576-585), Delta(566-585), Delta(558-585), Delta(523-585), and Delta(479-585) followed a monophasic unfolding process and showed a sequential reduction in the GdnCl concentration corresponding to half effect and DeltaG(0) for the unfolding. BlGGT-4aa and BlGGT sedimented at ~4.85 S and had a heterodimeric structure of approximately 65.23 kDa in solution, and this structure was conserved in all of the truncated proteins. The frictional ratio (f/f(o)) of BlGGT-4aa, BlGGT, Delta(581-585), and Delta(577-585) was 1.58, 1.57, 1.46, and 1.39, respectively, whereas the remaining enzymes existed exclusively as precursor form with a ratio of less than 1.18. Taken together, these results provide direct evidence for the functional role of the C-terminal region in the autocatalytic processing of BlGGT.

Essential covalent linkage between the chymotrypsin-like domain and the extra domain of the SARS-CoV main protease

The main protease of the coronavirus causing severe acute respiratory syndrome performs proteolytic processing of the viral polyproteins. The active form of the enzyme is a homodimer with each subunit consisting of three structural domains. Domains I and II, hosting the complete catalytic machinery, constitute the N-terminal chymotrypsin-like folding scaffold and connect to the extra C-terminal domain III by a long loop. Previously, the domain III-truncated enzyme was demonstrated to fold independently into an intact chymotrypsin-like fold, but it showed no enzyme activity. To further delineate the structure-function relationships of the domain III and the long loop, we generated some truncated and mutated M(pro) forms bearing various combinations of the loop with other structural parts of the enzyme. Their conformational and association properties were investigated in detail. Far-ultraviolet circular dichroism (CD) measurements revealed that these fragments could fold independently. The secondary, tertiary and quaternary structures of these mixtures were monitored by CD, fluorescence spectroscopy and analytical ultracentrifugation. However, no enzyme activity was observed for any mutant or mixtures. These observations indicate that the covalent linkage between the chymotrypsin like and the extra domain is essential for enzymatic activity of the main coronavirus protease and for the integrity of its quaternary structure.

Engineering of a truncated alpha-amylase of Bacillus sp. strain TS-23 for the simultaneous improvement of thermal and oxidative stabilities

BACDeltaNC/Delta RS is a thermostable variant derived from the truncated alpha-amylase (BAC Delta NC) of alkaliphilic Bacillus sp. strain TS-23. With the aim of enhancing its resistance towards chemical oxidation, Met231 of BAC Delta NC/Delta RS was replaced by leucine to create BAC Delta NC/Delta RS/M231L. The functional significance of the 31 C-terminal residues of BAC Delta NC/Delta RS/M231L was also explored by site-directed mutagenesis of the 483 th codon in the gene to stop codon (TAA), thereon the engineered enzyme was named BAC Delta NC/Delta RS/M231L/Delta C31. BAC Delta NC/Delta RS/M231L and BAC Delta NC/Delta RS/M231L/Delta C31 were very similar to BAC Delta NC in terms of specific activity, kinetic parameters, pH-activity profile, and the hydrolysis of raw starch; however, the engineered enzymes showed an increased half-life at 70 degrees C. The intrinsic fluorescence and circular dichroism spectra were nearly identical for wild-type and engineered enzymes, but they exhibited a different sensitivity towards GdnHCl-induced denaturation. This implicates that the rigidity of the enzyme has been changed as the consequence of mutations. Performance of the engineered enzymes was evaluated in the presence of commonly used detergent compounds and some detergents from the local markets. A high compatibility and performance of both BAC Delta NC/Delta RS/M231L and BAC Delta NC/Delta RS/M231L/Delta C31 may be desirable for their practical uses in the detergent industry.

Residues Leu52 and Leu134 are important for the structural integrity of a nucleotide exchange factor GrpE from Bacillus licheniformis

A DNA fragment encoding Bacillus licheniformis GrpE (BlGrpE) with double mutations at codons 52 and 134 was obtained during PCR cloning. Leu52 and Leu134 in BlGrpE were individually replaced with Pro and His to generate BlGrpE-L52P and BlGrpE-L134H. BlGrpE and BlGrpE-L52P synergistically stimulated the ATPase activity of B. licheniformis DnaK (BlDnaK); however, BlGrpE-L134H and the double-mutated protein (BlGrpE-L52P/L134H) had no co-chaperone function. BlGrpE, BlGrpE-L52P, and BlGrpE-L134H mainly interacted with the monomer of BlDnaK but non-specific interaction was observed for BlGrpE-L52P/L134H. Measurement of intrinsic fluorescence revealed a significant alteration of the microenvironment of aromatic acid residues in the mutant proteins. As compared with BlGrpE, quenching of 208-nm and 222-nm signals were observed in the mutant BlGrpEs and the single-mutated proteins were more sensitive to thermal denaturation.