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Expansion of the Substrate Specificity of Porcine Kidney D‐Amino Acid Oxidase for S ‐Stereoselective Oxidation of 4‐Cl‐Benzhydrylamine
Author(s) -
Yasukawa Kazuyuki,
Motojima Fumihiro,
Ono Atsushi,
Asano Yasuhisa
Publication year - 2018
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201800614
Subject(s) - stereoselectivity , chemistry , d amino acid oxidase , amino acid , enzyme , oxidase test , catalysis , substrate (aquarium) , stereochemistry , combinatorial chemistry , biochemistry , biology , ecology
Discovery and development of enzymes for the synthesis of chiral amines have been a hot topic for basic and applied aspects of biocatalysts. Based on our X‐ray crystallographic analyses of porcine kidney D‐amino acid oxidase (pkDAO) and its variants, we rationally designed a new variant that catalyzed the oxidation of ( S )‐4‐Cl‐benzhydrylamine (CBHA) from pkDAO and obtained it by functional high‐throughput screening with colorimetric assay. The variant I230A/R283G was constructed from the variant R283G which had completely lost the activity for D‐amino acids, further gaining new activity toward ( S )‐chiral amines with the bulky substituents. The variant enzyme (I230A/R283G) was characterized to have a catalytic efficiency of 1.85 s −1 for ( S )‐CBHA, while that for ( R )‐1‐phenylethylamine was diminished 10‐fold as compared with the Y228L/R283G variant. The variant was efficiently used for the synthesis of ( R )‐CBHA in 96 % ee from racemic CBHA by the deracemization reaction in the presence of reducing agent such as NaBH 4 in water. Furthermore, X‐ray crystallographic analysis of the new variant complexed with ( S )‐CBHA, together with modelling study clearly showed the basis of understanding the structure‐activity relationship of pkDAO.