Hydrogen-Bonding-Driven Enantioselective Resolution against the Kazlauskas Rule To Afford gamma-Amino Alcohols by Candida rugosa Lipase

초록

Most lipases resolve secondary alcohols in accordance with the "Kazlauskas rule" to give the R enantiomers. In a similar manner to other lipases, Candida rugosa lipase (CRL) exhibits R enantioselectivity towards heptan-2-ol, although the enantiomeric ratio (E) is low (E=1.6). However, unexpected enantioselectivity (i.e., S enantioselectivity, E=58) of CRL towards 4-(tertbutoxycarbonylamino)butan-2-ol, which has a similar chain length to heptan-2-ol, has been observed. To develop a deeper understanding of the molecular basis for this unusual enantioselectivity, we have conducted a series of molecular modeling and substrate engineering experiments. The results of these computational and experimental analyses indicated that a hydrogen bond between the Ser450 residue and the nitrogen atom of the carbamate group is critical to stabilize the transition state of the S enantiomer.

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