[Fortify clinical advantages and promote innovative development: comparison of the Chinese Colorectal Cancer Surgery Database with foreign databases]

With the continuous development of evidence-based medicine, increasing attention has been paid to the construction of a large medical database to ensure a source of high quality real-world data. The Chinese Medical Association Colorectal Surgery Group created the Chinese Colorectal Cancer Surgery Database (CCCD), whose objective is to promote the development of colorectal surgery and improve patient prognosis with evidence-based medicine theory. Compared to major databases around the world, CCCD contains more comprehensive information on colorectal cancer surgical cases, recording the main epidemiological characteristics and detailed surgical information, but perioperative treatment data still need to be strengthened. It is necessary to continuously expand the coverage, enrich perioperative data and strengthen data, quality control. In the future, CCCD is expected to play a role in promoting homogenization of medical services, promoting smooth and effective graded diagnosis and treatment, giving full role to the characteristics of each center to achieve integrated development, and connecting real-world data and artificial intelligence.

Perforating and nonperforating indications in repeated surgeries for Crohn’s disease

BACKGROUND

Despite advances in medical therapy for Crohn’s disease (CD), most patients with CD require repeated resection surgeries.

AIM

To analyze the perforating and nonperforating indications of repeated CD operations and identify the anastomosis characteristics for postoperative CD.

METHODS

We retrospectively reviewed 386 patients who underwent at least one resection for CD between 2003 and 2013.Clinical characteristics of each surgery were collected. Univariate and multivariate analyses were performed to determine risk factors for recurrence.

RESULTS

The indication for reoperation in CD tends to be the same as that for primary operation, i.e., perforating disease tends to represent as perforating disease and nonperforating as nonperforating. Concordance was found between the first surgery and second surgery in terms of the indication for the operation (P = 0.006), and the indication for the third surgery was also correlated with that for the second surgery (P = 0.033). Even if the correlation of surgical indications between repeated operations, the rate of perforating indication for the second and third surgeries was significantly higher than that of the first surgery. In addition, the presence of perforating CD was a predictor of recurrence for both the first and second surgeries. Moreover, anastomotic lesions were the most common sites of recurrence after the operation. Based on the importance of anastomosis, anastomosis might be a new type of disease location for the classification of postoperative CD.

CONCLUSION

CD not only has stable characteristics but also progresses chronically. Perforation is a progressive surgical indication for Crohn’s disease. For CD after surgery, anastomosis may be a new classification of disease location.

Dynamic prostatic and laser-ablated lesion volume change after transperineal laser ablation in canine: preliminary observation and its clinical significance

AIM

The purpose of this study is to observe the volume change of prostate and laser-ablated lesions in the canine and to explore the mechanism and clinical significance through histopathology.

MATERIALS AND METHODS

Transperineal laser ablation (TPLA) was performed under the guidance of transrectal ultrasound (TRUS) in eight canines. Two canines were sacrificed 1 day and 1 week after TPLA, respectively. The remaining six canines were sacrificed after finishing transrectal contrast-enhanced ultrasound (TR-CEUS) at three phases.

RESULTS

The prostatic volumes immediately following TPLA and 1 week later were larger than before TPLA (20.1 ± 3.9 vs 17.1 ± 3.8 ml; 21.7 ± 3.6 vs 17.1 ± 3.8 ml, p < 0.05), but 1 month later, returned to the preoperative level (17.4 ± 3.2 ml). At three time points, the mean volumes of laser-ablated lesions at 3 W/600 J were 0.6 ± 0.2, 1.1 ± 0.4, and 1.7 ± 0.5 ml, respectively, while those of laser-ablated lesions at 3 W/1200 J were 1.2 ± 0.2, 1.6 ± 0.3, and 2.2 ± 0.5 ml, respectively. The mean volumes of laser-ablated lesions increased significantly over time after TPLA (p < 0.050).

CONCLUSION

The prostate volume transient enlarges after TPLA, which prompts for clinical application that it should prolong appropriately the duration of urinary catheterization to avoid acute urinary retention. Many inflammatory cells were observed in the laser-ablated lesions and adjacent normal prostate parenchyma through histopathology. It is speculated that the inflammatory response is involved in the progression of tissue damage.

Synthesis of Biaryls via Decarbonylative Nickel-Catalyzed Suzuki-Miyaura Cross-Coupling of Aryl Anhydrides

Transition metal-catalyzed cross-couplings have been widely employed in the synthesis of many important molecules in synthetic chemistry for the construction of diverse C-C bonds. Conventional cross-coupling reactions require active electrophilic coupling partners, such as organohalides or sulfonates, which are not environmentally friendly enough. Herein, we disclose the first nickel-catalyzed Suzuki-Miyaura cross-coupling of aryl anhydrides and arylboronic acids for the synthesis of biaryls in a decarbonylation manner. The reaction tolerates a wide range of electron-withdrawing, electron-neutral, and electron-donating substituents in this process.

[Dynamics of three-dimensional ecological footprint of Zhejiang coastal zone and its influencing factors based on GTWR model]

Clarifying the consumption of local natural capital stock and natural capital flow and its influencing factors can help alleviate the tension between the socio-economic development of the coastal zone, natural resources, and the ecological environment, and promote regional coordinated and sustainable development. Based on the two-dimensional and three-dimensional ecological footprint evaluation models, we analyzed the spatial and temporal variations of ecological footprint in the coastal zone of Zhejiang Province from 2006 to 2016, and explored the regional natural capital stock and capital flow occupancy based on footprint depth and footprint width. We analyzed the spatial and temporal heterogeneity of its influencing factors using a geographically and temporally weighted regression model. The results showed that ecological crisis in the coastal zone of Zhejiang Province deepened during the study period. The average per capita ecological deficit was 3.5 hm²·cap^-1, and the per capita ecological deficit increased by 15.5%. Among them, the contribution of energy consumption account to the per capita ecological footprint was greater than that of the biological resources account. The per capita ecological footprint of each county showed an increasing trend, with significant spatial variation. The coastal zone of Zhejiang Province mainly consumed the natural capital stock, with a significant inhibitory effect on the renewal of natural capital flows. The consumption of natural capital stock was 14.87 times that of capital flow in 2016. Urban scale, economic development level, and people's income level had positive impacts on the ecological footprint of coastal counties of Zhejiang Province, while fishery production had negative effect on the ecological footprints, with transition trend to a positive one. The influence mechanism of the three factors had significant spatial and temporal differentiation.

[New research advances and clinical treatment of scar]

Scar formation is the abnormal healing process of skin after being damaged. The mechanism of scar formation is not clear, and many studies have shown that it is affected by many factors. Based on the over deposition of collagen in scars, many researchers have carried out studies on the mechanism, pathological manifestation, and treatment method of scars. In the treatment aspect of scar, the combination of traditional and new treatment methods has been well accepted and achieved good results. To understand the new advances of scar research and combine it with clinical treatment transformation could lead to the development of more effective prophylactic and therapeutic strategies for scar treatment in the future.

Bendable Network Built with Ultralong Silica Nanowires as a Stable Separator for High-Safety and High-Power Lithium-Metal Batteries

Separators are key safety components for electrochemical energy storage systems. However, the intrinsic poor wettability with electrolyte and low thermal stability of commercial polyolefin separators cannot meet the requirements of the ever-expanding market for high-power, high-energy, and high-safety power systems, such as lithium-metal, lithium-sulfur, and lithium-ion batteries. In this study, scalable bendable networks built with ultralong silica nanowires (SNs) are developed as stable separators for both high-safety and high-power lithium-metal batteries. The three-dimensional porous nature (porosity of 73%) and the polar surface of the obtained SNs separators endue a much better electrolyte wettability, larger electrolyte uptake ratio (325%), higher electrolyte retention ratio (63%), and ∼7 times higher ionic conductivity than that of commercial polypropylene (PP) separators. Moreover, the pore-rich structure of the SNs separator can aid in evenly distributing lithium and, in turn, suppress the uncontrollable growth of lithium dendrites to a certain degree. Furthermore, the pure inorganic structure endows the SNs separators with excellent chemical and electrochemical stabilities even at elevated temperatures, as well as excellent thermal stability up to 700 °C. This work underpins the utilization of SNs separators as a rational choice for developing high-performance batteries with a metallic lithium anode.

One-Pot Synthesis of N-Imidoyl-(1 H)-indoles via Palladium-Catalyzed Oxidative Insertion Domino Reaction with Isocyanide and Arylboronic Acid

Efficient one-pot synthesis of N-imidoyl-(1 H)-indoles has been described, which is achieved by the palladium-catalyzed oxidative insertion of 2-(phenylethynyl)aniline, arylboronic acid, and isonitrile. This method provides a new way to synthesize N-imidoyl-(1 H)-indoles, which has a wide substrate scope, good functional group tolerance, and mild reaction condition.

Influenza A (H1N1) pdm09 virus infection in a patient with incomplete Kawasaki disease: A case report

RATIONALE

Kawasaki disease (KD) is a vasculitic illness of childhood associated with coronary artery dilatation, coronary artery aneurysm, arrhythmia, sudden death, and other serious cardiovascular diseases. Up to date, the etiology of KD remains unclear; however, epidemiological characteristics indicate that it may be related to as-yet-undefined pathogen infection.

PATIENT CONCERNS

A 19-month-old boy had a fever of unknown origin at 38°C for 9 days without rash, runny nose and cough.

DIAGNOSIS

The boy was diagnosed with incomplete KD (IKD) coincident with influenza A (H1N1) pdm09 virus.

INTERVENTIONS

He was received treatments including human immunoglobulin (2 g/kg), aspirin (30∼50 mg/kg.d), and dipyridamole (3∼5 mg/kg.d).

OUTCOMES

After 24 hours of human immunoglobulin infusion, his body temperature returned normal. After hospitalization for 6 days, his symptoms disappeared and discharged from the hospital.

LESSONS

More attention should be paid to the correlation between KD and pathogen infection, especially the new influenza virus H1N1. The potential mechanism underlying viral infection-mediated KD is worthy of further investigation, which may provide scientific evidence for the pathogenesis of KD.

Prospective evaluation of intestinal decompression in treatment of acute bowel obstruction from Crohn's disease

Background

Conservative therapy for Crohn’s disease (CD)-related acute bowel obstruction is essential to avoid emergent surgery. The present study aimed to evaluate the efficacy of using a long intestinal decompression tube (LT) in treatment of CD with acute intestinal obstruction.

Methods

This is a prospective observational study. Comparative analysis was performed in CD patients treated with LT (the LT group) and nasogastric tube (the GT group). The primary outcome was the avoidance of emergent surgery. Additionally, predictive factors for failure of decompression and subsequent surgery were investigated.

Results

There were 27 and 42 CD patients treated with LT and GT, respectively, in emergent situations. Twelve (44.4%) patients using LT were managed conservatively without laparotomy, while only nine (21.4%) patients in the GT group were spared from emergent surgery (P < 0.05). Both in surgery-free and in surgery patients, the time to alleviation of symptoms was significantly shorter in the LT groups than in the GT groups (both P < 0.01). C-reactive protein decrease after intubation and 48-hour drainage volume >500 mL were predictors of unavoidable surgery (both P < 0.05). The rate of temporary stoma and incidence of incision infection in the LT surgery group were significantly lower than those in the GT group (both P < 0.05). No significant differences were observed in the frequency of medical and surgical recurrences between the LT and GT groups (all P > 0.05).

Conclusions

Endoscopic placement of LT could improve the emergent status in CD patients with acute bowel obstruction. The drainage output and changes in C-reactive protein after intubation could serve as practical predictive indices for subsequent surgery. Compared to traditional GT decompression, LT decompression was associated with fewer short-term complications and did not appear to affect long-term recurrence.

Menstruation recovery in scar pregnancy patients undergoing UAE and curettage and its influencing factors

This study aims to investigate the menstrual recovery outcome of scar pregnancy patients who received uterine artery embolization combined with curettage, and its influencing factors.The data of 119 patients with scar pregnancy, who received uterine artery embolization combined with curettage between December 2012 and December 2016 in Henan Provincival People's Hospital, were collected. The menstruation recovery of these patients was followed up, and factors that have influence on menstrual blood volume were analyzed using SPSS V.17.0.Follow-up data were available in 101/119 (84.9%) women. The median follow-up time was 22.7 months (range: 1.6-50.6 months); 58 (57.4%) patients had reduced menstrual blood volume, and 2 patients (2%) had amenorrhea. The proportion of patients with reduced menstrual blood volume, who were embolized with polyvinyl alcohol (PVA), PVA combined with gelatin sponge, and gelatin sponge between < and ≥33 years old was 41.7% versus 66.7%, 40% versus 57.1% and 60.6% versus 68.0%. The average age of patients with reduced menstrual blood volume (34.3 years) was greater than patients with normal menstrual blood volume (31.4 years), but the difference was not statistically significant (P = .07).Reduced menstrual blood volume can occur in scar pregnancy patients who received uterine artery embolization combined with curettage. The influence of the embolic agent PVA on menstrual blood volume depends on age, but the difference was not statistically significant.

[Recombinant human tumor necrosis factor receptor type Ⅱ-IgG Fc fusion protein for treatment of occupational medicamentosa-like dermatitis induced by trichloroethylene]

Objective: To investigate the efficacy and safety of the recombinant human tumor necrosis factor receptor Ⅱ-IgG Fc fusion protein (rhTNFR: Fc, etanercept) for the treatment of occupational medicamentosa-like dermatitis induced by trichloroethylene (OMLDT) . Methods: In September 2011 to February 2016, 12 patients with OMLDT were treated with etanercept 25 mg, subcutaneous injection, twice per week, doubling of first dose. The course of treatment was 6 weeks. The drug eruption area and severity index (DASI) score, the proportion of patients achieving a 50%, 75% and 90% reduction in DASI (DASI50, DASI75, DASI90) and the serum level of TNF-α were used to assess the efficacy at different times. Adverse reactions were also recorded and evaluated. The results were statistically analyzed by nonparametric Friedman test and repetitive measurement ANOVA using the software SPSS19.0. Results: After 4 weeks treatment, the DASI score decreased form 56.33±7.02 to 0.50±0.91 (P<0.01) . The DASI50, DASI75 and DASI90 were all increased to 12 (100%) . The serum level of TNF-α decreased form (43.74±41.62) pg/ml to (3.03±0.47) pg/ml (P<0.01) . Statistically significant difference was observed from the above indexes. There were no adverse reactions in clinical application. Conclusion: Recombinant human tumor necrosis factor receptor Ⅱ-IgG Fc fusion protein may be a safe and effective drug in the treatment of OMLDT.

Isolation and characterization of two VpYABBY genes from wild Chinese Vitis pseudoreticulata

The establishment of abaxial-adaxial polarity is an important feature of the development of lateral organs in plants. Members of the YABBY gene family may be specific to seed-plant-specific transcriptional regulators that play critical roles in promoting abaxial cell fate in the model eudicot, Arabidopsis thaliana. However, recent study has shown that the roles of YABBY genes are not conserved in the development of angiosperms. The establishment of abaxial-adaxial polarity has not been studied in perennial fruit crops. Grapes are an important fruit crop in many regions of the world. Investigating YABBY genes in grapevines should help us to discover more about the key genetic and molecular pathways in grapevine development. To understand the characterization of YABBY genes in grapevines, two YABBY genes, VpYABBY1 (GenBank accession No. KC139089) and VpYABBY2 (GenBank accession No. KC139090), were isolated from the wild Chinese species Vitis pseudoreticulata. Both of these encode YABBY proteins. Sequence characterization and phylogenetic analyses show that VpYABBY1 is group classified into the FIL subfamily while VpYABBY2 is a member of the YAB2 subfamily of Arabidopsis thaliana. Subcellular localization analysis indicates that VpYABBY1 and VpYABBY2 proteins are localized in the nucleus. Tissue specific expressional analysis reveals that VpYABBY1 is expressed strongly in young leaves of grape but only weakly in the mature leaves. Meanwhile, VpYABBY2 is expressed in grape stems, flowers, tendrils, and leaves. Transgenic Arabidopsis plants ectopically expressing VpYABBY1 caused the partial abaxialization of the adaxial epidermises of leaves, behaving similarly to those over-expressing FIL or YAB3 with abaxialized lateral organs. By contrast, ectopic expression of VpYABBY2 in Arabidopsis did not cause any alteration in the adaxial-abaxial polarity. Sequence characterization and phylogenetic analysis revealed that VpYABBY1 and VpYABBY2 are group-classified into two different subfamilies. They have diverged functionally in the control of lateral organ development. VpYABBY1 may have a function in leaf development, while VpYABBY2 may play a specific role in carpel development and grape berry morphogenesis. It is further possible that during the evolution of different species, YABBY family members have preserved different expression regulatory systems and functions.

Prognosis of the intrahepatic cholangiocarcinoma after resection: hepatitis B virus infection and adjuvant chemotherapy are favorable prognosis factors

Aim

The incidence and mortality associated with intrahepatic cholangiocarcinoma is increasing in many countries and documentation of disease outcome is sparse. The present study was undertaken to investigate the prognostic factors for intrahepatic cholangiocarcinoma (ICC) following surgical resection. The impact of pre-existing HBV virus infection and adjuvant chemotherapy on the overall survival was also evaluated.

Methods

Clinical and pathological data were collected retrospectively from 81 patients undergoing surgery for ICC between 2005 and 2011, at The Henan Province Tumor Hospital and the First Affiliated Hospital of Zheng Zhou University. Survival and prognosis were analyzed using the Kaplan-Meier method and COX regression model.

Results

The population included 37 patients who were HBsAg + or anti-HBc+, 21 patients who were anti-HBs + positive and 18 patients who received adjuvant chemotherapy. The overall 1- and 3-year survival rates were 51% and 20%, respectively. The median survival was 12.2 months. Univariate analysis identified the following prognostic factors: HBV virus infection or HBV vaccine prior to resection (P = 0.017); adjuvant chemotherapy (P = 0.001); preoperative serum CA19-9 (> 200 U/mL; P = 0.015); GGT (> 64 U/L; P = 0.008), ALP (> 119 U/L; P = 0.01); lymph node metastasis (P = 0.005); radical resection (P = 0.021); intrahepatic metastasis (P = 0.015) and diabetes (P = 0.07). Multivariate analysis identified chronic HBV infection (RR = 0.583; P = 0.041), anti-HBs positivity (RR = 0.680; P = 0.050), adjuvant chemotherapy (RR = 0.227; P < 0.001), lymph node metastasis (RR = 2.320; P = 0.001), and intrahepatic duct stones (RR = 0.473; P = 0.032) as independent prognostic factors.

Conclusions

HBV virus infection or HBV vaccination prior to resection, together with adjuvant chemotherapy, were independently associated with improved survival in patients undergoing surgery for ICC.

Detecting anti-FcepsilonRI autoantibodies in patients with asthma by flow cytometry

Autoimmune diseases have been implicated in the development of intrinsic asthma, however little data are available on the role of autoimmunity in the pathogenesis of asthma. The purpose of this study was to investigate circulating autoantibodies against the high-affinity receptor for immunoglobulin E, FcepsilonRI, in patients with asthma. Seventy-eight patients with asthma and 32 healthy control subjects were included. All individuals were tested using a triple-staining flow cytometry-based basophil activation test (BAT) for the potential presence of autoantibodies against FcepsilonRI. Of the 78 asthma patients, 29 (37.2%) had a positive BAT result, indicating that their serum was able to activate basophils, compared with only four (12.5%) of the control group, a statistically significant between-group difference. These data suggest that some asthma patients have aberrant anti-FcepsilonRI autoantibodies, which implies that autoimmunity may be one factor involved in the pathogenesis of intrinsic asthma.

Discovery of macrocyclic hydroxamic acids containing biphenylmethyl derivatives at P1', a series of selective TNF-alpha converting enzyme inhibitors with potent cellular activity in the inhibition of TNF-alpha release

SAR exploration at P1' using an anti-succinate-based macrocyclic hydroxamic acid as a template led to the identification of several bulky biphenylmethyl P1' derivatives which confer potent porcine TACE and anti-TNF-alpha cellular activities with high selectivity versus most of the MMPs screened. Our studies demonstrate for the first time that TACE has a larger S1' pocket in comparison to MMPs and that potent and selective TACE inhibitors can be achieved by incorporation of sterically bulky P1' residues.

Design and synthesis of a series of (2R)-N(4)-hydroxy-2-(3-hydroxybenzyl)-N(1)- [(1S,2R)-2-hydroxy-2,3-dihydro-1H-inden-1-yl]butanediamide derivatives as potent, selective, and orally bioavailable aggrecanase inhibitors

A pharmacophore model of the P1' site, specific for aggrecanase, was defined using the specificity studies of the matrix metalloproteinases and the similar biological activity of aggrecanase and MMP-8. Incorporation of the side chain of a tyrosine residue into compound 1 as the P1' group provided modest selectivity for aggrecanase over MMP-1, -2, and -9. A cis-(1S)(2R)-amino-2-indanol scaffold was incorporated as a tyrosine mimic (P2') to conformationally constrain 2. Further optimization resulted in compound 11, a potent, selective, and orally bioavailable inhibitor of aggrecanase.

Photochemically enhanced binding of small molecules to the tumor necrosis factor receptor-1 inhibits the binding of TNF-alpha

The binding of tumor necrosis factor alpha (TNF-alpha) to the type-1 TNF receptor (TNFRc1) plays an important role in inflammation. Despite the clinical success of biologics (antibodies, soluble receptors) for treating TNF-based autoimmune conditions, no potent small molecule antagonists have been developed. Our screening of chemical libraries revealed that N-alkyl 5-arylidene-2-thioxo-1,3-thiazolidin-4-ones were antagonists of this protein-protein interaction. After chemical optimization, we discovered IW927, which potently disrupted the binding of TNF-alpha to TNFRc1 (IC(50) = 50 nM) and also blocked TNF-stimulated phosphorylation of Ikappa-B in Ramos cells (IC(50) = 600 nM). This compound did not bind detectably to the related cytokine receptors TNFRc2 or CD40, and did not display any cytotoxicity at concentrations as high as 100 microM. Detailed evaluation of this and related molecules revealed that compounds in this class are "photochemically enhanced" inhibitors, in that they bind reversibly to the TNFRc1 with weak affinity (ca. 40-100 microM) and then covalently modify the receptor via a photochemical reaction. We obtained a crystal structure of IV703 (a close analog of IW927) bound to the TNFRc1. This structure clearly revealed that one of the aromatic rings of the inhibitor was covalently linked to the receptor through the main-chain nitrogen of Ala-62, a residue that has already been implicated in the binding of TNF-alpha to the TNFRc1. When combined with the fact that our inhibitors are reversible binders in light-excluded conditions, the results of the crystallography provide the basis for the rational design of nonphotoreactive inhibitors of the TNF-alpha-TNFRc1 interaction.

Design, synthesis, and structure-activity relationships of macrocyclic hydroxamic acids that inhibit tumor necrosis factor alpha release in vitro and in vivo

To search for TNF-alpha (tumor necrosis factor alpha) converting enzyme (TACE) inhibitors, we designed a new class of macrocyclic hydroxamic acids by linking the P1 and P2' residues of acyclic anti-succinate-based hydroxamic acids. A variety of residues including amide, carbamate, alkyl, sulfonamido, Boc-amino, and amino were found to be suitable P1-P2' linkers. With an N-methylamide at P3', the 13-16-membered macrocycles prepared exhibited low micromolar activities in the inhibition of TNF-alpha release from LPS-stimulated human whole blood. Further elaboration in the P3'-P4' area using the cyclophane and cyclic carbamate templates led to the identification of a number of potent analogues with IC(50) values of </=0.2 microM in whole blood assay (WBA). Although the P3' area can accommodate a broad array of structurally diversified functional groups including polar residues, hydrophobic residues, and amino and carboxylic acid moieties, in both the cyclophane series and the cyclic carbamate series, a glycine residue at P3' was identified as a critical structural component to achieve both good in vitro potency and good oral activity. With a glycine residue at P3', an N-methylamide at P4' provided the best cyclophane analogue, SL422 (WBA IC(50) = 0.22 microM, LPS-mouse ED(50) = 15 mg/kg, po), whereas a morpholinylamide at P4' afforded the most potent and most orally active cyclic carbamate analogue, SP057 (WBA IC(50) = 0.067 microM, LPS-mouse ED(50) = 2.3 mg/kg, po). Further profiling for SL422 and SP057 showed that these macrocyclic compounds are potent TACE inhibitors, with K(i) values of 12 and 4.2 nM in the porcine TACE assay, and are broad-spectrum MMP inhibitors. Pharmacokinetic studies in beagle dogs revealed that SL422 and SP057 are orally bioavailable, with oral bioavailabilities of 11% and 23%, respectively.

Design, synthesis, and evaluation of a pyrrolinone-based matrix metalloprotease inhibitor

[reaction: see text] A pyrrolinone-based hydroxamate matrix metalloprotease inhibitor, (-)-1, has been designed and synthesized. Enzymatic assay revealed that (-)-1 inhibited three of the ten matrix metalloprotease enzymes examined and as such represents a new, potentially important lead structure.

The thrombospondin motif of aggrecanase-1 (ADAMTS-4) is critical for aggrecan substrate recognition and cleavage

Aggrecanase-1 (ADAMTS-4) is a member of the a disintegrin and metalloprotease with thrombospondin motifs (ADAMTS) protein family that was recently identified. Aggrecanase-1 is one of two ADAMTS cartilage-degrading enzymes purified from interleukin-1-stimulated bovine nasal cartilage (Tortorella, M. D., Burn, T. C., Pratta, M. A. , Abbaszade, I., Hollis, J. M., Liu, R., Rosenfeld, S. A., Copeland, R. A., Decicco, C. P., Wynn, R., Rockwell, A., Yang, F., Duke, J. L., Solomon, K., George, H., Bruckner, R., Nagase, H., Itoh, Y., Ellis, D. M., Ross, H., Wiswall, B. H., Murphy, K., Hillman, M. C., Jr., Hollis, G. F., and Arner, E.C. (1999) Science 284, 1664-1666; 2 Abbaszade, I., Liu, R. Q., Yang, F., Rosenfeld, S. A., Ross, O. H., Link, J. R., Ellis, D. M., Tortorella, M. D., Pratta, M. A., Hollis, J. M., Wynn, R., Duke, J. L., George, H. J., Hillman, M. C., Jr., Murphy, K., Wiswall, B. H., Copeland, R. A., Decicco, C. P., Bruckner, R., Nagase, H., Itoh, Y., Newton, R. C., Magolda, R. L., Trzaskos, J. M., and Burn, T. C. (1999) J. Biol. Chem. 274, 23443-23450). The aggrecan products generated by this enzyme are found in cartilage cultures stimulated with cytokines and in synovial fluid from patients with arthritis, suggesting that aggrecanase-1 may be important in diseases involving cartilage destruction. Here we demonstrate that the thrombospondin type-1 (TSP-1) motif located within the C terminus of aggrecanase-1 binds to the glycosaminoglycans of aggrecan. Data from several studies indicate that this binding of aggrecanase-1 to aggrecan through the TSP-1 motif is necessary for enzymatic cleavage of aggrecan. 1) A truncated form of aggrecanase-1 lacking the TSP-1 motif was not effective in cleaving aggrecan. 2) Several peptides representing different regions of the TSP-1 motif effectively blocked aggrecanase-1 cleavage of aggrecan by preventing the enzyme from binding to the substrate. 3) Aggrecanase-1 was not effective in cleaving glycosaminoglycan-free aggrecan. Taken together, these data suggest that the TSP-1 motif of aggrecanase-1 is critical for substrate recognition and cleavage.

[Analysis on voice acoustic parameters and electroglottographic parameters in normal children of Han, Naxi, Bai nationality]

OBJECTIVE

To explore the normal vocal acoustic parameters and electroglottographic (EGG) parameters and their differences in normal children of the Han, the Naxi, the Bai nationality.

METHOD

By using computer and Dr. speech software, We studied six parameters of voice acoustic and the E.G.G. in 951 children (Han 342, Naxi 224, Bai 385), aged 4-8 years old. We also examined 30 cases who suffered from vocal nodule and local proliferation.

RESULT

The major parameters 1. Jitter, 2. Shimmer, 3. Mean F0, 4. SD F0, 5. NNE) of the voice acoustic and E.G.G. of the three nationality.

CONCLUSION

1. All parameters in Han nationality school-age children and preschool children were not different in years old. But Naxi and Bai nationality school-age children's Mean F0 and SD F0 were different from preschool children. The parameters(Mean F0, SD F0) of school-age children in Han, Naxi and Bai nationality were significant different. 2. The tested parameters were significant different between normal children of the Han nationality and the vocal nodule patients.

Sites of aggrecan cleavage by recombinant human aggrecanase-1 (ADAMTS-4)

Aggrecan, the major proteoglycan of cartilage that provides its mechanical properties of compressibility and elasticity, is one of the first matrix components to undergo measurable loss in arthritic diseases. Two major sites of proteolytic cleavage have been identified within the interglobular domain (IGD) of the aggrecan core protein, one between amino acids Asn(341)-Phe(342) which is cleaved by matrix metalloproteinases and the other between Glu(373)-Ala(374) that is attributed to aggrecanase. Although several potential aggrecanase-sensitive sites had been identified within the COOH terminus of aggrecan, demonstration that aggrecanase cleaved at these sites awaited isolation and purification of this protease. We have recently cloned human aggrecanase-1 (ADAMTS-4) (Tortorella, M. D., Burn, T. C., Pratta, M. A., Abbaszade, I., Hollis, J. M., Liu, R., Rosenfeld, S. A., Copeland, R. A., Decicco, C. P., Wynn, R., Rockwell, A., Yang, F., Duke, J. L., Solomon, K., George, H., Bruckner, R., Nagase, H., Itoh, Y., Ellis, D. M., Ross, H., Wiswall, B. H., Murphy, K., Hillman, M. C., Jr., Hollis, G. F., Newton, R. C., Magolda, R. L., Trzaskos, J. M., and Arner, E. C. (1999) Science 284, 1664-1666) and herein demonstrate that in addition to cleavage at the Glu(373)-Ala(374) bond, this protease cleaves at four sites within the chondroitin-sulfate rich region of the aggrecan core protein, between G2 and G3 globular domains. Importantly, we show that this cleavage occurs more efficiently than cleavage within the IGD at the Glu(373)-Ala(374) bond. Cleavage occurred preferentially at the KEEE(1667-1668)GLGS bond to produce both a 140-kDa COOH-terminal fragment and a 375-kDa fragment that retains an intact G1. Cleavage also occurred at the GELE(1480-1481)GRGT bond to produce a 55-kDa COOH-terminal fragment and a G1-containing fragment of 320 kDa. Cleavage of this 320-kDa fragment within the IGD at the Glu(373)-Ala(374) bond then occurred to release the 250-kDa BC-3-reactive fragment from the G1 domain. The 140-kDa GLGS-reactive fragment resulting from the preferential cleavage was further processed at two additional cleavage sites, at TAQE(1771)-(1772)AGEG and at VSQE(1871-1872)LGQR resulting in the formation of a 98-kDa fragment with an intact G3 domain and two small fragments of approximately 20 kDa. These data elucidate the sites and efficiency of cleavage during aggrecan degradation by aggrecanase and suggest potential tools for monitoring aggrecan cleavage in arthritis.

[Chromosome homologies between human and Francois' monkey (Semnopithecus francoisi) established by chromosome painting]

Chromosomal homologies were established between human and Francois' monkey (Semnopithecus francoisi, 2n = 44) by chromosome painting with chromosome-specific DNA probes of all human chromosomes except the Y. Except for human chromosome 1, 2, 6, 16 and 19 probes which gave signals on two nonhomologous S. francoisi chromosomes respectively, all other probes each hybridized to a single chromosome. Only two S. francoisi chromosomes (No. 12 and No. 21) were each labelled by two separate probes (14 and 15, 21 and 22, respectively). In total, 23 human chromosome-specific probed detected 30 homologous chromosomes and chromosomal segments in the haploid S. francoisi genome. The results indicated a high degree of conservation of chromosomal synteny between human and this langur. Only some chromosomal rearrangements occurred in this langur. Comparison of the hybridization patterns of human painting probes on this langur with the data on other primates suggested that Asian langurs were karyotypically more closely related to each other than to African langurs.

Cloning and characterization of ADAMTS11, an aggrecanase from the ADAMTS family

Aggrecan is responsible for the mechanical properties of cartilage. One of the earliest changes observed in arthritis is the depletion of cartilage aggrecan due to increased proteolytic cleavage within the interglobular domain. Two major sites of cleavage have been identified in this region at Asn(341)-Phe(342) and Glu(373)-Ala(374). While several matrix metalloproteinases have been shown to cleave at Asn(341)-Phe(342), an as yet unidentified protein termed "aggrecanase" is responsible for cleavage at Glu(373)-Ala(374) and is hypothesized to play a pivotal role in cartilage damage. We have identified and cloned a novel disintegrin metalloproteinase with thrombospondin motifs that possesses aggrecanase activity, ADAMTS11 (aggrecanase-2), which has extensive homology to ADAMTS4 (aggrecanase-1) and the inflammation-associated gene ADAMTS1. ADAMTS11 possesses a number of conserved domains that have been shown to play a role in integrin binding, cell-cell interactions, and extracellular matrix binding. We have expressed recombinant human ADAMTS11 in insect cells and shown that it cleaves aggrecan at the Glu(373)-Ala(374) site, with the cleavage pattern and inhibitor profile being indistinguishable from that observed with native aggrecanase. A comparison of the structure and expression patterns of ADAMTS11, ADAMTS4, and ADAMTS1 is also described. Our findings will facilitate the study of the mechanisms of cartilage degradation and provide targets to search for effective inhibitors of cartilage depletion in arthritic disease.

[Genetic relationships of Nyctereutes procyonopides: as inferred from random amplified polymorphic DNA analysis]

Random amplified polymorphic DNAs (RAPDs) were used to investigate genetic relationships of eight raccoon dogs (Nyctereutes procyonopides). Using 28 arbitrary primers (10 bp), about 130 RAPD markers were observed in each individual. The average, maximum, and minimum genetic distance among 8 raccoon dogs are 11.20%, 14.93%, and 2.94% respectively. Our molecular phylogenetic trees constructed by UPGMA and NJ methods suggest that those 8 Chinese raccoon dogs may be divided into 4 clusters: (1) Guangxi raccoon dog, (2) Anhui raccoon dog, (3) Shaanxi raccoon dog, (4) Yunnan and Vietnam raccoon dog. Guangxi raccoon dog is more closely related to Anhui raccoon dog than to Yunnan-Vietnam raccoon dog. If the Yunnan-Vietnam cluster is a valid subspecies, it is reasonable to give the Guangxi, Anhui and Shaanxi clusters the same classification status as that of the Yunnan-Vietnam Cluster.

[Smoking behaviour and its influencing factors among cigarette smokers in Beijing]

An investigation was carried out among 6,000 persons aged 15-70 to explore the prevalence of cigarette smoking and its risk factors in urban and suburban areas of Beijing. Results showed that 39.07% of Beijing residents were smokers (58.95% male, 17.42% female) who started smoking at an average age of 19.52% and over 2/3 of them admitted their initiafion of smoking was mainly due to curiosity and pressure from social intercourse. Results of polychotomas regression analysis demonstrated that the risk factors of smoking were related to sex, poor education, unhappy marriage, and lacking of knowledge on the negative health outcome of smoking. It is suggested that the program on smoking of control should be strengthened in Beijing.

Investigation of substrate activation by 4-chlorobenzoyl-coenzyme A dehalogenase

4-Chlorobenzoyl-coenzyme A (4-CBA-CoA) dehalogenase catalyzes the hydrolysis of 4-CBA-CoA to 4-hydroxybenzoyl-coenzyme A (4-HBA-CoA), using the carboxylate side chain of aspartate 145 to displace the chloride from C(4) of the benzoyl ring. Previous UV-visible, Raman, and 13C NMR studies of enzyme-bound substrate analog or product ligand indicated that the environment of the enzyme active site induces a significant reorganization of the benzoyl ring pi-electrons. This observation was interpreted as evidence for electrophilic catalysis [viz. active-site-induced polarization of electron density away from the ring C(4)] [Taylor, K. L., Liu, R.-Q., Liang, P.-H., Price, J., Dunaway-Mariano, D., Tonge, P. J., Clarkson, J., & Carey, P. R. (1995) Biochemistry 34, 13881]. The recent crystal structure of the dehalogenase-4-HBA-CoA complex reveals two hydrogen bonds contributed to the benzoyl C=O by the backbone amide protons of Gly114 and Phe64 and a possible dipolar interaction with the positive pole of the 114-121 alpha-helix. Residues closely surrounding the benzoyl ring include W137, D145, W89, F64, F82, and H90. In the present study, the mutants D145A, H90Q, W137F, W89F, W89Y, F64L, F82L, and G114A were prepared to examine the effect of amino acid substitution on catalysis and on perturbation of the UV-visible spectral properties of the substrate benzoyl ring. Substitution of the two catalytic residues D145 and H90 inhibited catalysis but not ligand binding or the induction of the red shift in the benzoyl ring absorption. These two residues do not appear to contribute to substrate benzoyl ring binding or polarization. The F64L, F82L, W89F, and W137F mutants retained substantial catalytic activity and the ability to induce the red shift. The W89Y mutant, on the other hand, is inhibited in catalysis and ligand binding, suggesting that hydrophobicity more than packing may be critical for the benzoyl ring binding/activation. The G114A mutant was shown to be strongly inhibited in both substrate binding and activation, indicating that H-bonding and/or interaction with the dipole of the 114-121 alpha-helix may be crucial.

Identification of active site residues essential to 4-chlorobenzoyl-coenzyme A dehalogenase catalysis by chemical modification and site directed mutagenesis

4-Chlorobenzoyl-coenzyme A (4-CBA-CoA) dehalogenase catalyzes the hydrolysis of 4-CBA-CoA to 4-hydroxybenzoyl-coenzyme A (4-HBA-CoA) via a nucleophilic aromatic substitution pathway involving the participation of an active site carboxylate side chain in covalent catalysis. In this paper we report on the identification of conserved aspartate, histidine, and tryptophan residues essential to 4-CBA-CoA catalysis using chemical modification and site-directed mutagenesis techniques. Treatment of the dehalogenase with diethyl pyrocarbonate resulted in complete loss of catalytic activity (Kinact = 0.17 mM-1 min-1 at pH 6.5, 25 degrees C) that was fully regained by subsequent treatment with hydroxylamine. The protection from inactivation afforded by enzyme bound 4-HBA-CoA indicated that the essential histidine residues are located at the active site. Replacement of conserved histidine residues 81, 90, 94, and 208 with glutamine residues resulted in a significant loss of catalytic activity only in the cases of the histidine 81 and 90 mutants. Substrate and product ligand binding studies showed that binding is not significantly inhibited in these mutants. Site directed mutagenesis of a selection of conserved aspartate and glutamate residues, identified aspartate 145 as being essential to dehalogenase catalysis. Ligand binding studies showed that this residue is not required for tight substrate/product binding. Chemical modification of the dehalogenase with N-bromosuccinimide resulted in full loss of catalytic activity that was prevented by saturation of the active site with product ligand, providing evidence favoring an essential active site tryptophan. Phenylalanine replacement of conserved tryptophan residues 179 and 137 reduced catalytic activity only in the latter (Kcat = 0.03% of wild-type dehalogenase). On the basis of these results and the recently determined X-ray crystal structure of the complex of 4-CBA-CoA dehalogenase and 4-HBA-CoA [Benning, M. M., Taylor, K.L., Liu, R.-Q., Yang, G., Xiang, H., Wesenberg, G., Dunaway-Mariano, D., Holden, H.M. (1996) Biochemistry 35,8103-8109] we propose that aspartate 145 functions as the active site nucleophile, that tryptophan 137 serves as a hydrogen bond donor to the aspartate 145 C = O, and that histidine 90 serves to deprotonate the bound H2O molecule.

Evidence for electrophilic catalysis in the 4-chlorobenzoyl-CoA dehalogenase reaction: UV, Raman, and 13C-NMR spectral studies of dehalogenase complexes of benzoyl-CoA adducts

This paper reports on the mechanism of substrate activation by the enzyme 4-chlorobenzoyl coenzyme A dehalogenase. This enzyme catalyzes the hydrolytic dehalogenation of 4-chlorobenzoyl coenzyme A (4-CBA-CoA) to form 4-hydroxybenzoyl coenzyme A (4-HBA-CoA). The mechanism of this reaction is known to involve attack of an active site carboxylate (Asp or Glu side chain) at C(4) of the substrate benzoyl ring to form a Meisenheimer complex. Loss of chloride ion from this intermediate results in the formation of an arylated enzyme intermediate. The arylated enzyme is hydrolyzed to free enzyme plus 4-HBA-CoA by the addition of water at the acyl carbon [Yang, G., Liang, P.-H., & Dunaway-Mariano, D. (1994) Biochemistry 33, 8527]. The present studies have focused on the activation of the 4-CBA-CoA for nucleophilic attack by the active site carboxylate group. UV-visible, 13C-NMR, and Raman spectroscopic techniques were used to monitor changes in the distribution of the pi electrons of the benzoyl moiety of benzoyl-CoA adducts [substituted at C(4) with methyl (4-MeBA-CoA), methoxy (4-MeOBA-CoA), or hydroxyl (4-HBA-CoA) groups or at C(2) or C(3) with a hydroxyl group (2-HBA-CoA and 3-HBA-CoA)] resulting from the binding of these ligands to the dehalogenase active site. The UV-visible spectra measured for 4-HBA-CoA in aqueous buffer at pH 7.5 and in the dehalogenase active site revealed that a large red shift (from 292 to 373 nm) in the lambda max of the benzoyl moiety occurs upon binding.(ABSTRACT TRUNCATED AT 250 WORDS)

Phylogenetic relationships among two species of golden monkey and three species of leaf monkey inferred from rDNA variation

Restriction maps of rDNA repeats of five species of Colobinae and three outgroup taxa, Hylobates leucogenys, Macaca mulatta, and Macaca irus, were constructed using 15 restriction endonucleases and cloned 18S and 28S rRNA gene probes. The site variation between Rhinopithecus roxellana and Rhinopithecus bieti is comparable to that between Presbytis françoisi and Preshytis phayrei, implying that R. bieti is a valid species rather than a subspecies of R. roxellana. Phylogenetic analysis on the 47 informative sites supports the case for Rhinopithecus being an independent genus and closely related to Presbytis. Furthermore, branch lengths of the tree seem to support the hypothesis that the leaf monkeys share some ancestral traits as well as some automorphic characters.

Photooxidation of Trp-191 in cytochrome c peroxidase by ruthenium-cytochrome c derivatives

A novel photoinduced electron-transfer reaction is reported in complexes between resting ferric state cytochrome c peroxidase (CcP) and several horse cytochrome c derivatives labeled at single lysine amino groups with [bis(bipyridine)](dicarboxybipyridine)ruthenium(II) (Ru-CC). Photoexcitation of Ru(II) in the 1:1 Ru-27-CC:CcP complex results in formation of a metal-to-ligand charge-transfer state, Ru(II*), which is a strong reducing agent and rapidly transfers an electron to the CC heme Fe(III) with rate constant k1 = 2.3 x 10(7) s-1. The resulting Ru(III) is a strong oxidizing agent with a redox potential of 1.3 V, and it oxidizes the indole ring of Trp-191 with rate constant k3 = 7 x 10(6) s-1. The cycle is completed by electron transfer from Fe(II) in CC to the Trp-191 radical in CcP with rate constant k4 = 6.1 x 10(4) s-1. The Ru group is located close to the interaction domain in the Ru-27-CC:CcP complex, allowing rapid electron transfer with both the heme in CC and Trp-191 in CcP. The electron-transfer reaction was not observed in CcP compound I, where Trp-191 is already oxidized to the radical, or in the W191F mutant, where the indole group is replaced with a phenyl group. The electron-transfer reaction was observed in CcP mutants modified at residues in the heme crevice, R48K, R48L, H52L, M230I, and M231I, but not in D235N which destabilizes the radical on Trp-191. Increasing the ionic strength results in an increase in the equilibrium dissociation constant K of the Ru-27-CC:CcP complex and an increase in the rate constant k5 for dissociation of the transient intermediate containing Fe(II) CC and the radical form of CcP. Both K and k5 were also increased significantly by the mutations D34N, E290N, and A193F involving residues located in the interaction domain of the crystalline complex between yeast CC and CcP [Pelletier & Kraut (1992) Science 258, 1748-1755]. This new method allows the study of the electron-transfer reaction between CC and the radical on Trp-191 in the complete absence of hydrogen peroxide, and it opens the possibility of measurements at low temperatures in frozen glasses or in crystals.

Design of ruthenium-cytochrome c derivatives to measure electron transfer to cytochrome c peroxidase

A new technique has been introduced to measure interprotein electron transfer which involves photoexcitation of a tris(bipyridine)ruthenium (Ru) complex covalently attached to one of the proteins. Four different strategies have been developed to specifically attach Ru to protein lysine amino groups, histidine imidazole groups, and cysteine sulhydryl groups. These strategies have been used to prepare more than 20 different singly-labeled Ru-cytochrome c derivatives. The new ruthenium photoexcitation technique has been used to study the mechanism for electron transfer between cytochrome c and cytochrome c peroxidase. Laser excitation of a complex between Ru-cytochrome c and cytochrome c peroxidase compound I results in formation of Ru(II*) which is a strong reducing agent, and rapidly transfers an electron to heme c Fe(III) to form Fe(II). The heme c Fe(II) then rapidly transfers an electron to the Trp-191 radical cation in CMPI. The rate constant for this reaction is 6 x 10(4) s-1 for a horse Ru-cytochrome c derivative labeled at lysine 27, and greater than 10(6) s-1 for yeast Ru-cytochrome c derivatives. A second laser flash results in electron transfer from heme c to the oxyferryl heme in cytochrome c peroxidase compound II with a rate constant of 350 s-1. The ruthenium photoreduction technique has been used to study the interaction domain between the two proteins, the pathway for electron transfer to the radical cation and the oxyferryl heme, and the specific residues in the heme crevice which control the electron transfer properties of the Trp-191 radical cation and the oxyferryl heme.

Genetic diversity in the Chinese pangolin (Manis pentadactyla) inferred from protein electrophoresis

We examined protein polymorphism of Chinese pangolins (Manis pentadactyla) from Yunnan Province of China, including two forms of three brown and nine dusky Chinese pangolins. Sixty-two genetic loci were screened; 12 loci were found to be polymorphic. The percentage of polymorphic loci (P) is 0.194, the mean individual heterozygosity (H) is 0.078, and the mean number of alleles (A) is 1.258. Furthermore, we calculated the genetic distance (D) between the two forms and found a low level of genetic divergence (D = 0.0206) between them, which indicates an almost-indistinguishable divergence at the level of proteins.

Role of methionine 230 in intramolecular electron transfer between the oxyferryl heme and tryptophan 191 in cytochrome c peroxidase compound II

The kinetics of electron transfer from cytochrome c (CC) to yeast cytochrome c peroxidase (CcP) compound I were studied by flash photolysis and stopped-flow spectroscopy. Flash photolysis studies employed horse CC derivatives labeled at specific lysine amino groups with (dicarboxybipyridine)bis-(bipyridine)ruthenium (Ru-CC). Initial electron transfer from Ru-CC reduced the indole radical on Trp-191 of CcP compound I [CMPI(IV,R.)], producing CMPII(IV,R). This reaction was biphasic for each of several Ru-CC derivatives, with rate constants which varied according to the position of the Ru label. For Ru-27-CC labeled at lysine 27, rate constants of 43,000 and 1600 s-1 were observed at pH 5.0 in 2 mM acetate. After reduction of the indole radical by Ru-CC, intramolecular electron transfer from Trp-191 to the oxyferryl heme in CMPII(IV,R) was observed, producing CMPII(III,R.). The rate constant and extent of this intramolecular electron transfer reaction were independent of both the protein concentration and the Ru-CC derivative employed. The rate constant decreased from 1100 s-1 at pH 5 to 550 s-1 at pH 6, while the extent of conversion of CMPII(IV,R) to CMPII(III,R.) decreased from 56% at pH 5 to 29% at pH 6. The reaction was not detected at pH 7.0 and above. The pH dependence of the rate and extent of this internal electron transfer reaction paralleled the pH dependence of the rate of bimolecular reduction of CMPII(IV,R) by native horse CC measured by stopped-flow spectroscopy at high ionic strength.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction domain for the reaction of cytochrome c with the radical and the oxyferryl heme in cytochrome c peroxidase compound I

Site-directed mutants of cytochrome c peroxidase (CcP) were created to modify the interaction domain between CcP and yeast iso-1-cytochrome c (yCC) seen in the crystal structure of the CcP-yCC complex [Pelletier & Kraut (1992) Science 258, 1748-1755]. In the crystalline CcP-yCC complex, two acidic regions of CcP contact lysine residues on yCC. Mutants E32Q, D34N, E35Q, E290N, and E291Q were used to examine the effect of converting individual carboxylate side chains in the acidic regions to amides. The A193F mutant was used to test the effect of introducing a phenyl moiety at the point of closest contact between CcP and yCC in the crystal structure. Stopped-flow experiments carried out in 310 mM ionic strength buffer at pH 7 revealed that yCC initially reduced the indole radical on Trp-191 of the parent CcP compound I with a bimolecular rate constant ka = 2.5 x 10(8) M-1 s-1. A second molecule of yCC subsequently reduced the oxyferryl heme of compound II with a rate constant kb = 5 x 10(7) M-1 s-1. The bimolecular rate constants ka and kb were affected in parallel by each mutation examined. CcP mutants D34N and E290N that are closest to a complementary yCC lysine residue in the crystalline CcP-yCC complex gave the lowest values for ka and kb, which were 25-50% of the values of the CcP parent. Mutants E32Q and E291Q that are removed from the interaction domain gave the same ka and kb values as the CcP parent.(ABSTRACT TRUNCATED AT 250 WORDS)

Intracomplex electron transfer between ruthenium-cytochrome c derivatives and cytochrome c1

The reactions of a beef heart cytochrome c1 preparation containing the hinge protein with horse cytochrome c derivatives labeled at specific lysine amino groups with (dicarboxybipyridine)(bisbipyridine)ruthenium(II) (Ru(II)) were studied by flash photolysis. All of the ruthenium-cytochrome c derivatives formed complexes with cytochrome c1 in low ionic strength buffer (5 mM sodium phosphate, pH 7). Excitation of Ru(II) to Ru(II*) with a 0.4-microseconds laser flash resulted in rapid electron transfer to the ferric heme group in cytochrome c, followed by electron transfer from the ferrous heme group of cytochrome c to the ferric heme group of cytochrome c1. The kinetic difference spectra displayed maxima at 546 nm and minima at 554 nm characteristic of electron transfer between the two cytochromes. The rate constants were independent of concentration at low ionic strength, indicating intracomplex electron transfer. The rate constants were 4,800, 6,800, 22,000, and 22,000 s-1 for cytochrome c derivatives modified at lysines 13, 27, 25, and 72, respectively. The observed rate constants were independent of ionic strength up to about 50 nM and then decreased progressively with further increases in ionic strength indicating dissociation of the complex. Second-order kinetics were observed at 310 mM ionic strength, with rate constants of 1.0 x 10(6), 1.6 x 10(7), 1.2 x 10(8), and 3.0 x 10(7) M-1 s-1 for the derivatives modified at lysines 13, 27, 25, and 72, respectively. The ionic strength dependence of the second-order rate constants is comparable to that involving native horse cytochrome c and is consistent with electron transfer reactions between oppositely charged proteins.

Intracomplex electron transfer between ruthenium-cytochrome c derivatives and cytochrome c oxidase

The reactions of bovine cytochrome c oxidase with horse cytochrome c derivatives labeled at specific lysine amino groups with (dicarboxybipyridine)bis(bipyridine)ruthenium (II) were studied by laser flash photolysis. All of the derivatives form complexes with cytochrome c oxidase at low ionic strength (5 mM sodium phosphate, pH 7). Excitation of Ru(II) to Ru(II*) with a short laser flash resulted in rapid electron transfer to the ferric heme group of cytochrome c, followed by electron transfer to cytochrome c oxidase. The photoreduced heme Fe(II) in the cytochrome c derivative modified at lysine 25 on the periphery of the heme crevice domain transferred an electron to CuA with a rate constant of 1.1 x 10(4) s-1. CuA then transferred an electron to cytochrome a with a rate constant of 2.3 x 10(4) s-1. The derivatives modified at lysines 7, 39, 55, and 60 remote from the heme crevice domain of cytochrome c have nearly the same kinetics. The rate constant for electron transfer from the cytochrome c heme to CuA is greater than 10(5) s-1, and the rate constant for electron transfer from CuA to cytochrome a is 2 x 10(4) s-1. The cytochrome c derivatives modified at lysines 13 and 27 in the heme crevice domain react much more slowly than the other derivatives, with intracomplex rate constants for oxidation of cytochrome c ranging from 1000 to 6000 s-1. The bulky ruthenium group at the heme crevice domain of these derivatives apparently alters the binding orientation, leading to smaller electron-transfer rates.(ABSTRACT TRUNCATED AT 250 WORDS)

Intracomplex electron transfer between ruthenium-65-cytochrome b5 and position-82 variants of yeast iso-1-cytochrome c

We tested the idea that the aromatic ring on the invariant residue Phe-82 in cytochrome c acts as an electron-transfer bridge between cytochrome c and cytochrome b5. Ru-65-cyt b5 was prepared by labeling the single sulfhydryl group on T65C cytochrome b5 with [4-(bromomethyl)-4'-methylbipyridine][bis(bipyridine)]ruthenium 2+ as previously described [Willie, A., Stayton, P.S., Sligar, S.G., Durham, B., & Millett, F. (1992) Biochemistry 31, 7237-7242]. Laser excitation of the complex formed between Ru-65-cyt b5 and Saccharomyces cerevisiae iso-1-cytochrome c at low ionic strength results in rapid electron transfer from the excited-state Ru(II*) to the heme group of Ru-65-cyt b5 followed by biphasic electron transfer to the heme group of cytochrome c with rate constants of (1.0 +/- 0.2) x 10(5) s-1 and (2.0 +/- 0.04) x 10(4) s-1. Variants of iso-1-cytochrome c substituted at Phe-82 with Tyr, Gly, Leu, and Ile have fast-phase rate constants of 0.4, 1.9, 2.1, and 2.0 x 10(5) s-1 and slow-phase rate constants of 5.3, 3.5, 2.4, and 2.0 x 10(3) s-1, respectively. Increasing the ionic strength to 50 mM results in single-phase intracomplex electron transfer with rate constants of 3.8, 3.1, 3.0, 5.0, and 4.5 x 10(4) s-1 for the wild-type, Tyr, Gly, Leu, and Ile variants, respectively. These results demonstrate that an aromatic side chain at residue 82 is not needed for rapid electron transfer with cytochrome b5. Furthermore, two conformational forms of the complex are present at low ionic strength with fast and slow electron-transfer rates.(ABSTRACT TRUNCATED AT 250 WORDS)