[Seminar] "New Trends in D-Amino acid Biocatalysis" by Prof. Loredano Pollegioni
Speaker: Prof. Loredano Pollegioni, University of Insubria
Title: New trends in D-Amino acid Biocatalysis
The increasing demand for enantiomerically pure amino acids and their derivatives from the chemical, pharmaceutical and agrochemical industry renewed the interest on single or multi-step biocatalytic processes. In this field, a major recent advance is represented by the application in biocatalysis of L-specific enzymes such as L-amino acid oxidases (LAAO) with a narrow substrate preference (e.g., L-aspartate oxidase) or L-amino acid deaminases (LAAD). These enzymes allowed the exploitation in biocatalysis of L-amino acids by overcoming the difficulty to produce recombinant canonical LAAOs. Various authors worldwide reported the use of LAADs (mainly as whole-cell system) to carry out biocatalysis on a number of L-amino acids in single- or multi-step cascade routes (with D-aminotransferase, D-amino acid dehydrogenase, D- or L-lactate dehydrogenase, etc.). We focused on the recombinant ProteusmyxofaciensLAAD to achieve the full resolution of a racemic solution of L-amino acids and the complete stereoinversion of 4-nitro-Phe using a small molar excess of borane tert-butylamine complex. Based on its 3D structure and sequential rounds of site-saturation mutagenesis, enzyme variants with an improved activity on the synthetic amino acid L-1-naphthylAla were isolated allowing the full resolution of the racemic mixture of this amino acid.
The evolved variants of both DAAO (e.g. M213G DAAO) and LAAD represents a competitive and versatile biocatalytic system for α-keto acid production, deracemization and stereoinversion of amino acids of biotechnological relevance.