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An Aminocaprolactam Racemase from Ochrobactrum anthropi with Promiscuous Amino Acid Ester Racemase Activity
Author(s) -
Frese Amina,
Barrass Sarah V.,
Sutton Peter W.,
Adams Joe P.,
Grogan Gideon
Publication year - 2018
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.201800265
Subject(s) - enantiopure drug , kinetic resolution , chemistry , saturated mutagenesis , enzyme , stereochemistry , amino acid , biochemistry , enantiomer , biocatalysis , mutant , enantioselective synthesis , reaction mechanism , catalysis , gene
Abstract The kinetic resolution of amino acid esters (AAEs) is a useful synthetic strategy for the preparation of single‐enantiomer amino acids. The development of an enzymatic dynamic kinetic resolution (DKR) process for AAEs, which would give a theoretical yield of 100 % of the enantiopure product, would require an amino acid ester racemase (AAER); however, no such enzyme has been described. We have identified low AAER activity of 15 U mg −1 in a homologue of a PLP‐dependent α‐amino ϵ‐caprolactam racemase (ACLR) from Ochrobactrum anthropi . We have determined the structure of this enzyme, Oa ACLR, to a resolution of 1.87 Å and, by using structure‐guided saturation mutagenesis, in combination with a colorimetric screen for AAER activity, we have identified a mutant, L293C, in which the promiscuous AAER activity of this enzyme towards l ‐phenylalanine methyl ester is improved 3.7‐fold.