Abstract 1302 Developing a PLP-dependent Mannichase for biocatalytic synthesis of alpha-beta-diamino acids

α,β-Diamino acids are important building blocks for natural products and pharmaceuticals. To synthesize these stereoarrays, the direct asymmetric Mannich reaction represents a powerful approach which allows modular assembly of the amino acid backbone and simultaneous construction of two vicinal stereocenters in one-step. Despite that numerous catalytic systems have been developed, there is no biocatalyst available to catalyze Mannich reaction to access α,β-Diamino acids until now. Here, we report the discovery of a PLP-dependent Mannich cyclase, LolT, from the biosynthetic pathway of loline alkaloids. Through kinetic analysis and structural characterization, we gained a comprehensive mechanistic and structural understanding on how LolT catalyzes efficient stereoselective cyclization. These insights further allowed us to successfully engineer LolT to catalyze direct intermolecular Mannich reactions with high stereoselectivity for the first time. We also demonstrate that the utility of LolT for scalable preparation of enantiopure α,β-diamino acids This work is supported by an NIH grant GM151205 and a grant from the ACS GCIPR.