Guocheng Du
Jiangnan University, China
Title: One-step biosynthesis of α-keto acids by the L-amino acid deaminase: Biocatalyst construction and process optimization
Biography
Biography: Guocheng Du
Abstract
L-Amino Acid Oxidases (LAAOs) which catalyze the stereo-specific oxidative deamination of L-amino acids to α-ketoacids and ammonia are flavinadenine dinucleotide containing homodimeric proteins. L-Amino acid oxidases are widely distributed in diverse organisms and have a range of properties. In this work, we systematically engineered the LAAO from Proteus vulgaris as a robust biocatalyst for the efficient one-step biosynthesis of a-keto acids including α-ketoglutaric acid, α-keto-γ-methyl thiobutyric acid and phenyl pyruvic acid which are currently produced by multi-step chemical synthesis with heavy environmental pollution. First, the directed evolution of LAAO was done by error-prone Polymerase Chain Reaction (PCR) and then the site-saturation mutagensis was conducted at the mutation sites of the positive mutants yielded by error-prone PCR. The biotransformaton conditions included biocatalyst concentration, the substrates concentration, temperature and pH and so on. The maximum titers of α-ketoglutaric acid, α-keto-γ-methyl thiobutyric acid and phenyl pyruvic acid are 12.3 g/L, 63.6 g/L and 11.8 g/L, respectively under the specific optimal conditions. Compared with the traditional multi-step chemical synthesis, our one-step biocatalytic production of a-keto acids has an advantage in terms of less environmental pollution and thus has great potential for industrial production of a-keto acids.
