Probing the enantioselectivity of Bacillus subtilis esterase BS2 for tert. alcohols

An Enzymatic Toolbox for the Kinetic Resolution of 2‐(Pyridin‐x‐yl)but‐3‐yn‐2‐ols and Tertiary Cyanohydrins

“…Similar catalytic behavior has previously been observed with GGG(A)X hydrolases [14,20,21] and commercially available lipases, [29] proteases, [15] and whole-cell biocatalysts [16][17][18] and seems to be the general rule in the conversion of these very difficult substrates.…”

“…Furthermore, molecular modeling indicated that the main difference in substrate recognition of esterase BS2 between tertiary alcohols with an ethynyl substituent and tertiary cyanohydrins lies in the ability of the nitrile group to form hydrogen bonds with water molecules in the active site of the enzyme. [14] These observations suggest that the solvation of solvent-exposed groups may be an important factor in the enantiorecognition of esterases.…”

“…A molecular dynamics study indicated that the main difference between tertiary alcohols with an ethynyl substituent and tertiary cyanohydrins lies in the ability of the nitrile group to form hydrogen bonds with water molecules in the active site of the enzyme. [14] The kinetic resolution of 1a, 1b, 1c, 1e, and 1i was also performed in experiments on the 100 mg scale. The reaction products were isolated in moderate-to-good yields and with excellent enantiopurity (Table 2).…”

“…The enantioselective hydrolysis of their esters by carboxyl esterases is a promising alternative to the addition of HCN to ketones as the starting compounds are easy to prepare. [14,15] When a neutral pH is used in the reaction, the cyanohydrin formed decomposes into the corresponding ketone and HCN. The resulting ketones can be reused for the synthesis of the corresponding racemic esters.…”

Double substituted variant of Bacillus amyloliquefaciens esterase with enhanced enantioselectivity and high activity towards 1-(3′,4′-methylenedioxyphenyl)ethyl acetate

“…Different strategies such as ep-PCR (Reetz et al 1997;Ma et al 2013;Qin et al 2013), saturation mutagenesis (Reetz et al 2006;Carballeira et al 2007;Kotik et al 2011), and rational design (Ema et al 2005(Ema et al , 2010Heinze et al 2007;Bordes et al 2009;Bassegoda et al 2010) have been successfully applied to generate enzyme variants with excellent enantioselectivity. The paranitrobenzyl esterase containing a GGG(A)X-motif has high catalytic activity towards esters of chiral tertiary alcohols (Henke et al 2003), and great efforts have been made to improve its enantioselectivity for tertiary alcohols by protein engineering, providing insights into the molecular mechanism of enzymes (Heinze et al 2007;Kourist et al 2007;Barbayianni et al 2009;Wiggers et al 2009). …”