Enzymological characterization of a novel d-lactate dehydrogenase from
Lactobacillus rossiae and its application in d-phenyllactic acid synthesis.
3 Biotech 2020;
10:101. [PMID:
32099742 DOI:
10.1007/s13205-020-2098-5]
[Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 01/24/2020] [Indexed: 12/28/2022] Open
Abstract
A novel lactate dehydrogenase gene, named lrldh, was cloned from Lactobacillus rossiae and heterologously expressed in Escherichia coli. The lactate dehydrogenase LrLDH is NADH-dependent with a molecular weight of approximately 39 kDa. It is active at 40 °C and pH 6.5 and stable in a neutral to alkaline environment below 35 °C. The kinetic constants, including maximal reaction rate (V max), apparent Michaelis-Menten constant (K m), turnover number (K cat) and catalytic efficiency (K cat/K m) for phenylpyruvic acid were 1.95 U mg-1, 2.83 mM, 12.29 s-1, and 4.34 mM-1 s-1, respectively. Using whole cells of recombinant E. coli/pET28a-lrldh, without coexpression of a cofactor regeneration system, 20.5 g l-1 d-phenyllactic acid with ee above 99% was produced from phenylpyruvic acid in a fed-batch biotransformation process, with a productivity of 49.2 g l-1 d-1. Moreover, LrLDH has broad substrate specificity to a range of ketones, keto acids and ketonic esters. Taken together, LrLDH is a promising biocatalyst for the efficient synthesis of d-phenyllactic acid and other fine chemicals.
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