Green access to chiral Vince lactam in a buffer-free aqueous system using a newly identified substrate-tolerant (−)-γ-lactamase

Abstract

A novel non-heme chloroperoxidase (SvGL) with promiscuous (−)-γ-lactamase activity towards Vince lactam was identified from Streptomyces viridochromogenes by genome data-mining. SvGL possesses high activity and excellent thermal stability and enantioselectivity. Furthermore, it is able to tolerate extremely high substrate concentrations (4.0 M, 436.5 g L⁻¹). Using the newly discovered (−)-γ-lactamase as a biocatalyst, an efficient and environmentally benign process for the production of (+)-γ-lactam was developed. The process allowed an enantioselective resolution of 436.5 g L⁻¹ racemic γ-lactam with only 0.2 g L⁻¹ lyophilized cell-free extract, affording an extremely high substrate/catalyst ratio of 2183 (g g⁻¹), a space-time yield of 458 g L⁻¹ d⁻¹, and a very low E factor (environmental factor) of 5.7 (kg waste per kg product) even when the process water is included.