Virtual Substrates Screening Model of Triacylglycerol Lipase from Bacillus thermocatenulanatus

A reliable 3-D structure of Triacylglycerol lipase from Bacillus thermocatenulanatus was constructed by homology modeling. Under molecular dynamics simulation, it was refined and checked. The model was further used as a receptor to search binding sites and carry out flexible docking with a range of substrates, whose enzyme activities were already measured. By inputting a series of docking results, virtual substrates screening models were established and assessed. Monadic nonlinear solution demanded less data but was weak in fitting enzyme activity data with little difference; its mean absolute percentage error （MAPE） of regression was 0.67 and mean square error （MSE） was 1.73 U/mg. Both quadratic stepwise regression and BP neural network were good in regression and prediction; however, more data were required. In the cross-validation of 12 groups, overall MAPE of regression and prediction for the former were 0.18 and 0.49, while the latter was 0.55 and 0.36. MSE values for these two methods were 0.95 and 1.20 U/mg, respectively. Therefore, monadic nonlinear regression model can be used as a preliminary screening one; quadratic stepwise regression and BP neural network approach can be applied to precise screening.

Enantioselective Resolution of(R,S)-Carvedilol to(S)-(2)-Carvedilol by Biocatalysts

Among the microorganisms employed in the study,Aspergillus niger(GUFCC5443),Escherichia coli(ATCC9637),Streptomyces halstedii(CKM-2),Pseudomonas putida(NCIB9494),Cunninghamella elegans(NCIM689)and Sphingomonas paucimobilis(NCTC11030)were capable for the enantioselective conversion of racemic Carvedilol.Immobilization technique enhanced the enantioselectivity of microorganisms and thus increased the enantiomeric purity of the drug.Excellent enantiomeric ratios(E)were found in reactions catalyzed by immobilized A.niger and E.coli with values 174.44 and 104.26,respectively.Triacylglycerol lipase from Aspergillus niger was also employed in this study as a biocatalyst which resulted in the product with 83.35%enantiomeric excess(ee)and E of 11.34 while the enzyme on immobilization has yielded 99.08%ee and 216.39 E.The conversion yield(C%)of the drug by free-enzyme was 57.42%,which was enhanced by immobilization to 90.51%.Hence,our results suggest that immobilized triacylglycerol lipase from A.niger(Lipase AP6)could be an efficient biocatalyst for the enantioselective resolution of racemic Carvedilol to(S)-(-)-Carvedilol with high enantiomeric purity followed by immobilized cultures of A.niger and E.coli.

Apolipoprotein A-V gene therapy for disease prevention/treatment:a critical analysis

Apolipoprotein（apo） A-V is a novel member of the class of exchangeable apo＇s involved in triacylglycerol（TG）homeostasis.Whereas a portion of hepatic-derived apoA-V is secreted into plasma and functions to facilitate lipoprotein Iipase-mediated TG hydrolysis,another portion is recovered intracellularly,in association with cytosolic lipid droplets.Loss of apo A-V function is positively correlated with elevated plasma TG and increased risk of cardiovascular disease.Single nucleotide polymorphisms（SNP） in the APOA5 locus can affect transcription efficiency or introduce deleterious amino acid substitutions.Likewise,rare mutations in APOA5 that compromise functionality are associated with increased plasma TG and premature myocardial infarction.Genetically engineered mouse models and human population studies suggest that,in certain instances,supplementation with wild type（WT） apoA-V may have therapeutic benefit.It is hypothesized that individuals that manifest elevated plasma TG owing to deleterious APOA5 SNPs or rare mutations would respond to WT apoA-V supplementation with improved plasma TG clearance.On the other hand,subjects with hypertriglyceridemia of independent origin（unrelated to apoA-V function） may not respond to apoA-V augmentation in this manner.Improvement in the ability to identify individuals predicted to benefit,advances in gene transfer technology and the strong connection between HTG and heart disease,point to apoA-V supplementation as a viable disease prevention / therapeutic strategy.Candidates would include individuals that manifest chronic TG elevation,have low plasma apoA-V due to an APOA5 mutation/polymorphism and not have deleterious mutations/polymorphisms in other genes known to influence plasma TG levels.