Substrate promiscuity in evolved Alcohol Dehydrogenase A (ADH-A)

Alcohol dehydrogenase A (ADH-A) from Rhodococcus ruber DSM 44541 tolerates organic solvents, and therefore this became a useful biocatalyst for asymmetric synthesis of organic compounds.1 ADH-A is capable of catalyzing stereoselective oxidation of phenyl-substituted sec-alcohols and reduction of the corresponding ketones. Importantly, these compounds are precursors for the synthesis of a range of biologically active compounds.1,2 Therefore, we have been studying engineering of ADH-A for the purpose of developing new enzymes with pre-designed catalytic properties regarding substrate scope and selectivity. We have been isolated a number of ADH-A variants which have been isolated from CASTing libraries for different purposes and function. Variants isolated from a library originally generated from random mutagenesis of residues Y294 and W295 (called “A”, clones A1, A2, A2C3 and A2C2B1) represent hits from different generation of directed evolution, selected for improved activity for the non-preferred R-enantiomer of 1-phenylethanol.2 Other mutants that were selected (variants B1 and B1F4) for improved activity with a disubstituted sec-alcohol also displayed altered regioselectivity as compared to the wild type.3 In a third evolution effort, enzyme variants C1 and C1B1 were isolated after selection for improved activity with the vicinal diol (R)-1-pheny-1,2-ethanediol.4 Please click Additional Files below to see the full abstract

The angle of a side-chain decides regio- and enantioselectivity in Alcohol Dehydrogenase A

Alcohol dehydrogenase A (ADH-A) from Rhodococcus ruber DSM 44541 is a promising biocatalyst for asymmetric synthesis of organic compounds.1 This enzyme is capable of catalyzing enantio- and regioselectivity of phenyl-substitute a-hydroxy ketones (acyloins), which are precursors for the synthesis of a range of biologically active compounds.1,2 ADH-A catalyzes the oxidation of (S)-1-phenylethanol 3000-fold more efficiently as compared to the 2-hydroxylated derivatives (R)-phenyl-1,2-ethanediol. ADH-A is highly selective towards secondary-alcohols and displays very low activities with corresponding primary-alcohol derivatives.2,3 Apparently, when this selectivity was tested with substrate contained two secondary-alcohols, we analyzed the catalytic efficiency and the regioselectivity towards (1R,2S)-2.2 The conclusions were yielded that ADH-A is a comparably inefficient catalyst for oxidation of vicinal diols, but displays regioselectivity, oxidizing primarily the benzylic carbon of this substrate.2 Please click Additional Files below to see the full abstract

Редокс-регуляция динамического характера фенотипа эндотелиоцитов кровеносных сосудов

ЭНДОТЕЛИАЛЬНЫЕ КЛЕТКИКЛЕТКИЭНДОТЕЛИЙКРОВЕНОСНЫЕ СОСУДЫФЕНОТИПГЕНЕТИЧЕСКИЕ ФЕНОМЕНЫОКИСЛИТЕЛЬНО-ВОССТАНОВИТЕЛЬНЫЕ РЕАКЦИИЭНЕРГЕТИЧЕСКИЙ ОБМЕНПЕРЕКИСНОЕ ОКИСЛЕНИЕ ЛИПИДО

Protein engineering for development of new hydrolytic biocatalysts

Hydrolytic enzymes play important roles as biocatalysts in chemical synthesis. The chemical versatility and structurally sturdy features of Candida antarctica lipase B has placed this enzyme as a common utensil in the synthetic tool-box. In addition to catalyzing acyl transfer reactions, a number of promiscuous activities have been described recently. Some of these new enzyme activities have been amplified by mutagenesis. Epoxide hydrolases are of interest due to their potential as catalysts in asymmetric synthesis. This current update discusses recent development in the engineering of lipases and epoxide hydrolases aiming to generate new biocatalysts with refined features as compared to the wild-type enzymes. Reported progress in improvements in reaction atom economy from dynamic kinetic resolution or enantioconvergence are also included