Mining and characterization of thermostable (+)-γ-lactamases for asymmetric resolution of γ-lactam

• 1、 Bioengineering School, Jiangnan University, Wuxi 214000

Abstract：Optically pure γ-lactam is an important pharmaceutical intermediate. (-)-γ-lactam can be used to synthesize antiviral drugs such as abacavir and palamivir, while (+)-γ-lactam can be used to synthesize drug targets such as megliptin and MK-0812. Enzymatic kinetic resolution of racemic γ-lactam (also known as Vince lactam) is an important strategy for the synthesis of optically pure γ-lactam. In this study, a novel thermostable (+)-γ-lactamase TmLM from Thermaerobacter marianensis was identified by genome-mining and heterologously expressed in E. coli BL21(DE3). TmLM can specifically hydrolyze (+)-γ-lactam for the preparation of (-)-γ-lactam. Phylogenetic analysis shows that TmLM belongs to type II (+)-γ-lactamase. The optimum pH and temperature of TmLM the reaction are 7.0 and 60℃, respectively. Additionally, the half-life of TmLM was determined to be 20 h at 70℃. When catalyzed by whole cells, 50.5% conversion of 2 M γ-lactam was achieved at a substrate to catalyst ratio (S/C) of 21.8 and space-time yield of 108 g L-1 d-1in 24 h.

Keywords： Biocatalysis (+)-γ-lactamase γ-lactam Gene mining Asymmetric resolution