Purification, characterization, and overexpression of psychrophilic and thermolabile malate dehydrogenase of a novel antarctic psychrotolerant, Flavobacterium frigidimaris KUC-1.
We purified the psychrophilic and thermolabile malate dehydrogenase to homogeneity from a novel psychrotolerant, Flavobacterium frigidimaris KUC-1, isolated from Antarctic seawater. The enzyme was a homotetramer with a molecular weight of about 123 k and that of the subunit was about 32 k. The enzyme required NAD(P)(+) as a coenzyme and catalyzed the oxidation of L-malate and the reduction of oxalacetate specifically. The reaction proceeded through an ordered bi-bi mechanism. The enzyme was highly susceptible to heat treatment, and the half-life time at 40 degrees C was estimated to be 3.0 min. The k(cat)/K(m) (microM(-1).s(-1)) values for L-malate and NAD(+) at 30 degrees C were 289 and 2,790, respectively. The enzyme showed pro-R stereospecificity for hydrogen transfer at the C4 position of the nicotinamide moiety of the coenzyme. The enzyme contained 311 amino acid residues and much lower numbers of proline and arginine residues than other malate dehydrogenases.
Oikawa
Tadao
T
Department of Biotechnology, Faculty of Engineering, Kansai University, Osaka, Japan. oikawa@ipcku.kansai-u.ac.jp
Yamamoto
Noriko
N
Shimoke
Koji
K
Uesato
Shinichi
S
Ikeuchi
Toshihiko
T
Fujioka
Toru
T
D000864:Antarctic Regions; D002384:Catalysis; D003080:Cold Temperature; D004795:Enzyme Stability; D005417:Flavobacterium / Q000201:enzymology*; D006358:Hot Temperature; D008291:Malate Dehydrogenase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D008293:Malates / Q000378:metabolism; D009249:NADP; D010071:Oxaloacetates / Q000378:metabolism; D013237:Stereoisomerism
D008293:Malates; D010071:Oxaloacetates; D009249:NADP; C030298:malic acid; D008291:Malate Dehydrogenase