Abstract
Hydroxyacid dehydrogenases are responsible for the conversion of 2-keto acids to 2-hydroxyacids and have a wide range of biotechnological applications. In this study, a D-lactate dehydrogenase (D-LDH) from a Sporolactobacillus inulinus strain was experimentally verified to have both the D-LDH and glutamate dehydrogenase (GDH) activities (reversible deamination). The catalytic mechanism was demonstrated by identification of key residues from the crystal structure analysis and site-directed mutagenesis. The Arg234 and Gly79 residues of this enzyme play a significant role in both D-LDH and GDH activities. His295 and Phe298 in DLDH744 were identified to be key residues for lactate dehydrogenase (LDH) activity only whereas Tyr101 is a unique residue that is critical for GDH activity. Characterization of the biochemical properties contributes to understanding of the catalytic mechanism of this novel D-lactate dehydrogenase enzyme.
Highlights
Hydroxyacid dehydrogenases are responsible for stereospecific conversion of 2-keto acids to 2-hydroxyacids [1, 2]
We previously reported that a novel D-lactate dehydrogenase from Sporolactobacillus inulinus CASD (DLDH744) could use both NADH and NADPH and even with a preference for NADPH as the coenzyme, which is different from the coenzyme utilization of all previously reported LDHs [12]
D-phenyllactic acid was detected as the product from phenylpyruvate, indicating DLDH744 is a strict D-2-hydroxyacid dehydrogenase
Summary
Hydroxyacid dehydrogenases are responsible for stereospecific conversion of 2-keto acids to 2-hydroxyacids [1, 2]. Given the wide range of biotechnological applications in industry [3, 4, 5, 6], it is of significant biological interest to gain in-depth insights into the enzymes. Lactate dehydrogenase (LDH), one of the hydroxyacid dehydrogenases, is a terminal glycolytic enzyme. It catalyzes the (reversible) reduction of pyruvate to lactic acid, concomitant with the oxidation of NADH to NAD+ [2]. A hydride ion is transferred from NADH to pyruvate during this reaction; reversely, it is transferred to NAD+ from lactate. A unifying feature of all previously reported lactate dehydrogenases is their strict specificity for NAD+ as a cofactor [7]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
