89378-59-6Relevant academic research and scientific papers
Discovery and Redesign of a Family VIII Carboxylesterase with High (S)-Selectivity toward Chiral sec-Alcohols
Park, Areum,Park, Seongsoon
, p. 2397 - 2402 (2022/02/17)
Highly enantioselective lipase has been widely utilized in the preparation of versatile enantiopure chiral sec-alcohols through kinetic or dynamic kinetic resolution. Lipase is intrinsically (R)-selective, and it is difficult to obtain (S)-selective lipase. Recent crystal structures of a family VIII carboxylesterase have revealed that the spatial array of its catalytic triad is the mirror image of that of lipase but with a catalytic triad that is distinct from lipase. We, therefore, hypothesized that the family VIII carboxylesterase may exhibit (S)-enantioselectivity toward sec-alcohols similar to (S)-selective serine protease, whose catalytic triad is also spatially arrayed as its mirror image. In this study, a homologous enzyme (carboxylesterase from Proteobacteria bacterium SG_bin9, PBE) of a known family VIII carboxylesterase (pdb code: 4IVK) was prepared, which showed not only moderate (S)-selectivity toward sec-alcohols such as 3-butyn-2-ol and 1-phenylethyl alcohol but also (R)-selectivity toward particular sec-alcohols among the substrates explored. Furthermore, the (S)-selectivity of PBE has been significantly improved by rational redesign based on molecular modeling. Molecular modeling identified a binding pocket composed of Ser381, Ala383, and Arg408 for the methyl substituent of (R)-1-phenylethyl acetate and suggested that larger residues may increase the enantioselectivity by interfering with the binding of the slow-reacting enantiomer. As predicted, substituting Ser381with larger residues (Phe, Tyr, and Trp) significantly improved the (S)-selectivity of PBE toward all sec-alcohols explored, even the substrates toward which the wild-type PBE exhibits (R)-selectivity. For instance, the enantioselectivity toward 3-butyn-2-ol and 1-phenylethyl alcohol was improved from E = 5.5 and 36.1 to E = 2001 and 882, respectively, by single mutagenesis (S381F).
Enhancing enantioselectivity of Candida antarctica lipase B towards chiral sec-alcohols bearing small substituents through hijacking sequence of A homolog
Yi, Seonghyeon,Park, Seongsoon
, (2021/06/21)
Candida antarctica lipase B (CAL-B) exhibits extraordinary enantioselectivity towards most chiral sec-alcohols but not towards sec-alcohols bearing substituents smaller than a propyl group (i.e., (±)-but-3-yn-2-ol (E = 4) and (±)-butan-2-ol (E = 7)). Previously, we reported a homologous enzyme (lipase from Pseudozyma brasiliensis GHG001, PBL) of CAL-B, which exhibited high enantioselectivity of CAL-B towards (±)-but-3-yn-2-ol (E > 200). Based on the result, we hypothesized that the comparison of their local sequence or structure would provide a clue for enhancing the enantioselectivity of CAL-B. In this paper, we report enhancing enantioselectivity of CAL-B towards (±)-but-3-yn-2-ol and (±)-butan-2-ol through the substitution of the local sequence of CAL-B with that of PBL. The sequence-substituted mutant of CAL-B exhibited much higher enantioselectivity towards (±)-but-3-yn-2-ol (E > 200) and (±)-butan-2-ol (E > 25).
