Using BpyAla to generate copper artificial metalloenzymes: a catalytic and structural study

Artificial metalloenzymes (ArMs) have emerged as a promising avenue in the field of biocatalysis, offering new reactivity. However, their design remains challenging due to the limited understanding of their protein dynamics and how the introduced cofactors alter the protein scaffold structure. Here we present the structures and catalytic activity of novel copper ArMs capable of (R)- or (S)-stereoselective control, utilizing a steroid carrier protein (SCP) scaffold. To incorporate 2,2'-bipyridine (Bpy) into SCP, two distinct strategies were employed: either Bpy was introduced as an unnatural amino acid (2,2'-bipyridin-5-yl)alanine (BpyAla) using amber stop codon expression or via bioconjugation of bromomethyl-Bpy to cysteine residues. The resulting ArMs proved to be effective at catalysing an enantioselective Friedel-Crafts reaction with SCP_Q111BpyAla achieving the best selectivity with an enantioselectivity of 72% ee (S). Interestingly, despite using the same protein scaffold, different attachment strategies for Bpy at the same residue (Q111) led to a switch in the enantiopreference of the ArM. X-ray crystal structures of SCP_Q111CBpy and SCP_Q111BpyAla ArMs with bound Cu(ii) ions unveiled crucial differences in the orientation of the catalytic centre. Combining structural information, alanine scanning studies, and computational analysis shed light on the distinct active sites of the ArMs, clarifying that these active sites stabilise the nucleophilic substrate on different sides of the electrophile leading to the observed switch in enantioselectivity. This work underscores the importance of integrating structural studies with catalytic screening to unravel the intricacies of ArM behaviour and facilitate their development for targeted applications in biocatalysis.

Ameliorative effect of Arabic gum Acacia and mori extracts in streptozotocin-induced diabetic rats: implications of Cas-3 and TGF-β

OBJECTIVE

Arabic gum Acacia (AG) is rich in fiber which improves lipid metabolism besides its antioxidant effect. Folium mori (FM) is a widely used herb due to its immunomodulatory, antimicrobial, and antioxidant activity. In the current study, we explore the antidiabetic, anti-inflammatory, as well as antioxidant activities of AG and FM in Streptozotocin (STZ), induced diabetic rats.

MATERIALS AND METHODS

STZ diabetic rats were orally administrated with metformin and/or a combination of AG and FM for 4 weeks. Glycemic levels, Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), cholesterol, triglycerides, urea, and creatinine were determined. Malondialdehyde (MDA), glutathione peroxidase (GPx), and Superoxide dismutase (SOD) were also evaluated. Gene expression and profile as well as immunohistopathological were also evaluated.

RESULTS

The results elicited no toxicological profile of both AG and FM. Plasma glucose level was decreased starting from 1st week to 4th week; besides, there was an improvement in glycated hemoglobin, insulin, and fructosamine. Liver and kidney damage markers were decreased in both AG and FM-treated rats. A significant increase in the antioxidant defense system and a decrease in oxidative stress markers were also observed. Gene expression analysis in brain tissues revealed a significant decrease in Interleukin beta 1 (IL-β1), Caspase 3 (Cas-3), and Transforming growth factor beta (TGF-β).

CONCLUSIONS

Oral treatment of metformin with AG and FM in STZ-injected rats could ameliorate protective pathways and can be one of the promising oral anti-diabetic herbal agents.

Serotonin and histamine mediate gastroprotective effect of fluoxetine against experimentally-induced ulcers in rats

Research in the treatment of gastric ulcer has involved the investigation of new alternatives, such as anti-depressant drugs. The present study was designed to investigate the gastroprotective effects of fluoxetine against indomethacin and alcohol induced gastric ulcers in rats and the potential mechanisms of that effect. Fluoxetine (20 mg/kg) was administered IP for 14 days. For comparative purposes, other rats were treated with ranitidine (30 mg/kg). Thereafter, after 24 h of fasting, INDO (100 mg/kg) or absolute alcohol (5 ml/kg) was administered to all rats (saline was administered to naïve controls) and rats in each group were sacrificed 5 h (for INDO rats) or 1 h (for alcohol rats) later. Macroscopic examination revealed that both fluoxetine and ranitidine decreased ulcer scores in variable ratios, which was supported by microscopic histopathological examination. Biochemical analysis of fluoxetine- or ranitidine-pre-treated host tissues demonstrated reductions in tumor necrosis factor (TNF)-α and myeloperoxidase (MPO) levels and concomitant increases in gastric pH, nitric oxide (NO) and reduced glutathione (GSH) contents. Fluoxetine, more than ranitidine, also resulted in serotonin and histamine levels nearest to control values. Moreover, immuno-histochemical analysis showed that fluoxetine markedly enhanced expression of cyclo-oxygenases COX-1 and COX-2 in both models; in comparison, ranitidine did not affect COX-1 expression in either ulcer model but caused moderate increases in COX-2 expression in INDO-induced hosts and high expression in alcohol-induced hosts. The results here indicated fluoxetine exhibited better gastroprotective effects than ranitidine and this could be due to anti-secretory, anti-oxidant, anti-inflammatory and anti-histaminic effects of the drug, as well as a stabilization of gastric serotonin levels.

Heroin profiling: mannitol hexaacetate as an unusual ingredient of some illicit drug seizures

Mannitol hexaacetate (MHA) has been detected by GC-MS in some brown illicit drug seizures in which diacetylmorphine (DAM) was completely lacking. The presence of MHA as a genuine ingredient of the drug seizures rather than a storage- or an analytical artifact, formed by transacetylation of mannitol with the DAM in the heroin, has been verified. It is argued that MHA was formed as a result of the addition of mannitol, as diluent, before the acetylating step in the process of the heroin preparation. This early dilution in the production and distribution chain of the illicit drug is deemed as peculiar, nonetheless it may be highly indicative of a specific production process of heroin in a trafficking organization.

The use of cyclohexanone as a "derivatizing" reagent for the GC-MS detection of amphetamines and ephedrines in seizures and the urine

A GC-MS method has been developed for the detection of amphetamine, methamphetamine, and the ephedrines, in seizures and the urine, based on on-GC condensation (derivatization) with cyclohexanone. The method is simple: the dried seizure material or the urine extract was mixed with cyclohexanone and injected into the GC-MS. The method was found to be superior to the methods based on acyl and trimethylsilyl (TMS) derivatization. Unlike for the acyl and TMS derivatives, the molecular and fragment ions of the cyclohexanone condensation products (cyclohexanone derivatives) were of substantial abundance, a useful property in unambiguous compound characterization. Furthermore, the high stability of the "derivatizing" reagent, cyclohexanone, compared with acyl and TMS derivatizing reagents, is a useful property in method development. The present method has proved selective and, tentatively, sensitive enough in the following areas (where methods based on acyl and TMS derivatization, as tested in this laboratory, have failed): (a) detection of amphetamine as a metabolite of methamphetamine; (b) detection of norpseudoephedrine as a metabolite of pseudoephedrine; (c) detection of amphetamine as an impurity of methamphetamine; (d) detection of cathine (norephedrine) as a constituent of Khat leaves; and (e) differentiation of Khat use from phenylpropanolamine use.

Increased bcl-2 expression is associated with primary resistance to chemotherapy in human epithelial ovarian cancer

OBJECTIVE

bcl-2, an anti-apoptotic factor, has a role in the pathogenesis of ovarian cancer as well as in resistance to chemotherapy.

DESIGN AND METHODS

20 benign, and 26 malignant epithelial ovarian tissues were analyzed for bcl-2 protein and mutant p53 by enzyme-immunoassay (EIA). Flowcytometric analysis was also performed. Patients of malignant group were followed up to monitor overall survival and primary resistance to chemotherapy.

RESULTS

bcl-2 was significantly higher in malignant group than benign group (p < 0.001). A cutoff value was determined for bcl-2 (63.8 kU/g protein). At this cutoff, sensitivity is 80.7%, and specificity is 85%. Using chi square analysis, a significant correlation was found between bcl-2 and FIGO stage (p = 0.01), overall survival (p = 0.01), as well as primary resistance to chemotherapy (p = 0.03). By correlation coefficient analysis the relation between bcl-2 and synthetic phase fraction was highly significant (p = 0.002). Bcl-2, p53, and FIGO stage were significantly correlated to poor survival (p = 0.01) in univariate analysis. However, in multivariate analysis, only FIGO stage, and p53 were independent risk factors.

CONCLUSION

EIA could be a useful tool for investigating the prognostic value of bcl-2, and its possible prediction of platinum resistance in epithelial ovarian cancer. This might help in selecting patients for future anti-bcl-2 therapy.

Ectopic pregnancy presenting with obturator nerve pain

A 27 year old woman had a three day history of pain in the cutaneous distribution of the left obturator nerve before she developed the classical picture of ectopic pregnancy with lower abdominal pain and vaginal bleeding. A left tubal pregnancy was subsequently confirmed by laparoscopy. Referred pain along the obturator nerve has been reported in other pelvic conditions, but has not previously been reported as a manifestation of ectopic pregnancy. Ectopic pregnancy may present with a very wide range of signs and symptoms and should be excluded in females of child bearing age with unexplained symptoms including pain anywhere from the shoulder down to the knee.