title: Identification and characterization of a mycobacterial NAD⁺-dependent alcohol dehydrogenase with superior reduction of diacetyl to (S)-acetoin.
abstract: An enzyme capable of reducing acetoin in the presence of NADH was purified from Mycobacterium sp. B-009, a non-clinical bacterial strain of soil origin. The enzyme is a homotetramer and can be classified as a medium-chain alcohol dehydrogenase/reductase based on the molecular weight of the monomer. Identification of the structural gene revealed a limited distribution of homologous genes only among actinomycetes. In addition to its activity as a reductase specific for (S)-acetoin (EC 1.1.1.76), the enzyme showed both diacetyl reductase (EC 1.1.1.304) and NAD(+)-dependent alcohol dehydrogenase (EC 1.1.1.1) activities. (S)-Acetoin and diacetyl reductases belong to a group of short-chain alcohol dehydrogenase/reductases but do not have superior abilities to dehydrogenate monoalcohols. Thus, the purified enzyme can be readily distinguished from other enzymes. We used the dual functionality of the enzyme to effectively reduce diacetyl to (S)-acetoin, coupled with the oxidation of 1-butanol.
authors.affiliation: a Division of Materials Science and Chemical Engineering, Graduate School of Engineering , Yokohama National University , Yokohama , Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Takeda
authors.forename: Shiori
authors.initials: S
authors.lastname: Anamizu
authors.forename: Shigekazu
authors.initials: S
authors.lastname: Motomatsu
authors.forename: Xue
authors.initials: X
authors.lastname: Chen
authors.forename: Rajan
authors.initials: R
authors.lastname: Thapa Chhetri
mesh_terms: D000093:Acetoin / Q000737:chemistry / Q000378:metabolism*; D000426:Alcohol Dehydrogenase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D003931:Diacetyl / Q000737:chemistry / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009161:Mycobacterium / Q000145:classification / Q000201:enzymology*; D010084:Oxidation-Reduction; D010802:Phylogeny; D013379:Substrate Specificity
chemical_list: D000093:Acetoin; D000426:Alcohol Dehydrogenase; D003931:Diacetyl
keywords: (S)-acetoin; Mycobacterium; NADH recycle; diacetyl; reductase