| 초록 |
Creation of enzyme variants displaying enhanced catalytic properties necessitates a precise understanding on reaction mechanism in the context of active site environment. Despite the great potential of ω-transaminases (ω-TAs) in asymmetric synthesis of chiral amines, it remains elusive why ω-TAs exhibit marginal activities for ketones although the resulting amines are good substrates. Here, we carried out crystal structure determination and molecular modeling of ω-TAs and revealed that ketones, unlike pyruvate and benzaldehyde, result in formation of a nonproductive Michaelis complex where the carbonyl carbon of the bound substrate is inaccessible to a nucleophilic attack required to initiate the catalytic pathway. This finding led us to perform computational redesign of the active site, guided by substrate binding orientations, to confer an enzyme activity to sterically demanding ketones. |
