Reducing 3,4-dihydroxyphenylpyruvic acid to
d-3,4-dihydroxyphenyllactic acid via a coenzyme nonspecific d-lactate dehydrogenase from Lactobacillus reuteri.
J Appl Microbiol 2018;
125:1739-1748. [PMID:
30129993 DOI:
10.1111/jam.14077]
[Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 08/07/2018] [Accepted: 08/11/2018] [Indexed: 01/11/2023]
Abstract
AIMS
The purpose of this work was to find an efficient enzyme to synthesize d-3,4-dihydroxyphenyllactic acid (d-DSS).
METHODS AND RESULTS
Nineteen lactic acid bacteria strains were screened for production of d-DSS using 3,4-dihydroxyphenylpyruvic acid (DPA) as a substrate. Lactobacillus reuteri JN516 exhibited the highest d-DSS yield. A nonspecific coenzyme, d-lactate dehydrogenase (d-LDH82319), from L. reuteri JN516 with high DPA reducing activity was identified. This enzyme reduced DPA to form d-DSS with excellent optical purity (enantioselectivity >99%). Its molecular weight was 35 kDa based on SDS-PAGE migration. The Michaelis-Menten constant (Km ), turnover number (kcat ), and catalytic efficiency (kcat /Km ) of d-LDH82319 for DPA were 0·09 mmol l-1 , 2·17 s-1 and 24·07 (mmol l-1 )-1 s-1 , respectively, with NADH as the coenzyme. The (Km ), (kcat ) and (kcat /Km ) of d-LDH82319 for DPA were 0·10 mmol l-1 , 0·13 s-1 and 1·30 (mmol l-1 )-1 s-1 , respectively, with NADPH as the coenzyme. The optimum temperature and pH of d-LDH82319 were 25°C and pH 8 respectively. Additionally, d-LDH82319 had a broad substrate range for alpha-keto acids, among which the activity of reducing pyruvate was the strongest; therefore, it belongs to the group of d-lactate dehydrogenases. d-LDH82319 and glucose dehydrogenase (GDH) were coexpressed to produce d-DSS from DPA.
CONCLUSIONS
d-LDH82319 from L. reuteri JN516 with high DPA reducing activity has the characteristics of a nonspecific coenzyme.
SIGNIFICANCE AND IMPACT OF THE STUDY
d-LDH82319 is the first reported coenzyme nonspecific d-lactate dehydrogenase with DPA-reducing activity. The coexpression system provided an effective method to produce d-DSS.
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