Zhu dunming and Wu Qiqing of Tianjin Institute of technology have made new progress in D-amino acid dehydrogenase transformation and D-amino acid synthesis with high steric hindrance

In addition to most functions of natural amino acids, non natural D-amino acids also have excellent properties which are not possessed by natural amino acids They are widely used in drug synthesis (medicine and pesticide), food, cosmetics, etc Using D-amino acid dehydrogenase, D-amino acid can be produced by reduction and ammoniation of ketone acid and ammonium salt However, D-amino acid dehydrogenase is rarely found in nature, and the most studied is a kind of meso diaminoheptanoate dehydrogenase (dapdh) Dapdh and its mutants can asymmetric reduce aminated 2-ketoacids to produce corresponding D-amino acids, such as D-valine, D-leucine, D-phenylalanine, etc However, dapdh is very difficult to act on some large steric 2-ketoacids, such as 3,3-dimethyl-2-oxobutyric acid, phenylglyoxylic acid and indole-3-pyruvate The team of biocatalysis and green chemical industry led by Zhu dunming, researcher of Tianjin Institute of industrial biotechnology, Chinese Academy of Sciences and Wu Qiqing, explored the molecular mechanism of this kind of enzyme and expanded its application potential in D-amino acid synthesis on the basis of previous research work For the meso-diaminoheptylhydrogenase (stdadpdh) from symbiobium thermophilum ）A mutant w121l / h227i was obtained by semi rational design and saturation mutation It not only showed excellent activity to the substrate of large steric resistance 2-ketoacids, but also successfully synthesized corresponding D-amino acids (d-phenylglycine, D-TRYPTOPHAN, d-tert-leucine), and improved the specific activity to other structures 2-ketoacids Through docking simulation, the substrate and wild-type and mutant molecules were docking, and it was found that the mutant substrate binding pocket was remolded, which not only can accommodate these large steric inhibitors, but also shorten the catalytic distance between the substrate and coenzyme, so that it can obtain the catalytic activity to the large steric inhibitors This result provides a basis for further remolding the substrate binding pocket and obtaining highly active D-amino acid dehydrogenase to synthesize more challenging D-amino acids Relevant research results have been published on catalysis science & Technology (catalyst.sci Technology., 2018, 8, 4994-5002) The research work was supported by the National Natural Science Foundation of China (No 21778072), Tianjin Science and Technology Committee (15ptcysy00020 and 15ptgccx00060) Cheng Xinkuan, a doctoral candidate from Tianjin Institute of industrial biology, Chinese Academy of Sciences, is the first author of this paper.