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Insight of Pseudomonas cepacia lipase enantioselectivity towards chiral 1-phenyl ethanol and its derivates

A systematic research of PCL (Pseudomonas cepacia lipase) catalyzed kinetic resolution of 1-phenyl ethanol and its derivatives have been done. PCL shows a high activity toward 1-phenyl ethanol and its derivatives when in n-hexane at 40 o C with a α w 0.73 and use vinyl butyrate as acyl donor. The conversion ratio is all higher than 40% after a 72 h reaction, but the enantioselectivity is different according to distribution of substituents, the E value of (R,S)-1-(4-methoxyphenyl) ethanol is only 2.5 while (R,S)-2-chloro-1-phenylethanol is higher than 200. At the same time for small groups containing strong polar substituent, such as chlorine, which often occurs stereoselective inversion. Consequently, docking approach has been used to investigate its catalytic mechanism. Hydrogen bonds, substrate conformation and binding affinity in the binding site were analyzed. It was found that better enzyme preference towards a substrate was correlated with a critical hydrogen bond (His286-Oγ). The binding energy is also analyzed, the calculation result is consistent with the experimental result.