earticle

영어

Most lipases cannot hydrolyze amides although their active sites are similar to those of serine-proteases that catalyze hydrolysis of amides. Recently, we proposed molecular basis for the enhanced lipasecatalyzed N-acylation of 1-phenylethanamine with methoxyacetate. We suggested that the hydrogen atom connected to the nitrogen atom of the amine substrate may interrupt formation of the key hydrogen bond between the catalytic histidine and the nitrogen atom of the substrate. The disruption could be avoided by using methoxyacetate as an acyl donor. The methoxy group of the acyl donor can hydrogen bond with the nitrogen atom and thus the proton does not interrupt the key hydrogen bond. We introduced a residue to serve a similar role of the methoxy group into a lipase. We prepared a mutant of Candida antarctica lipase B (CAL-B) to construct a hydrogen bond between the residue introduced and the nitrogen atom. The mutant enzyme clearly showed improved hydrolysis activity toward p-nitroacetanilide.