title: Crystal structure and thermodynamic properties of d-lactate dehydrogenase from Lactobacillus jensenii.
abstract: The thermostable d-lactate dehydrogenase from Lactobacillus jensenii (Ljd-LDH) is a key enzyme in the production of the d-form of lactic acid from pyruvate concomitant with the oxidation of NADH to NAD(+). The polymers of d-lactic acid are used as biodegradable bioplastics. The crystal structures of Ljd-LDH and in complex with NAD(+) were determined at 2.13 and 2.60Å resolutions, respectively. The Ljd-LDH monomer consists of the N-terminal substrate-binding domain and the C-terminal NAD-binding domain. The Ljd-LDH forms a homodimeric structure, and the C-terminal NAD-binding domain mostly enables the dimerization of the enzyme. The NAD cofactor is bound to the GxGxxG NAD-binding motif located between the two domains. Structural comparisons of Ljd-LDH with other d-LDHs reveal that Ljd-LDH has unique amino acid residues at the linker region, which indicates that the open-close dynamics of Ljd-LDH might be different from that of other d-LDHs. Moreover, thermostability experiments showed that the T50(10) value of Ljd-LDH (54.5°C) was much higher than the commercially available d-lactate dehydrogenase (42.7°C). In addition, Ljd-LDH has at least a 7°C higher denaturation temperature compared to commercially available d-LDHs.
authors.affiliation: School of Life Sciences, KNU Creative BioResearch Group (BK21 plus program), Kyungpook National University, Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea; School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Republic of Korea.
authors.forename: Sangwoo
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Chemical Engineering, Kwangwoon University, Seoul 139-701, Republic of Korea.
authors.forename: Sol-A
authors.initials: SA
authors.lastname: Gu
authors.affiliation: Department of Chemical Engineering, Kwangwoon University, Seoul 139-701, Republic of Korea. Electronic address: metalkim@kw.ac.kr.
authors.forename: Yong Hwan
authors.initials: YH
authors.lastname: Kim
authors.affiliation: School of Life Sciences, KNU Creative BioResearch Group (BK21 plus program), Kyungpook National University, Daehak-ro 80, Buk-ku, Daegu 702-701, Republic of Korea. Electronic address: kkim@knu.ac.kr.
authors.forename: Kyung-Jin
authors.initials: KJ
authors.lastname: Kim
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004795:Enzyme Stability; D007700:Kinetics; D045022:Lactate Dehydrogenases / Q000737:chemistry* / Q000378:metabolism*; D007778:Lactobacillus / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D011994:Recombinant Proteins; D009243:NAD; D045022:Lactate Dehydrogenases; C071195:D-lactate dehydrogenase
keywords: Lactobacillus jensenii; Polylactic acid; d-Lactate dehydrogenase