Enzymatic Characterization of Salmonella typhimurium Mannitol Dehydrogenase Expressed in Escherichia coli
2012
Jang, M.U., Chungbuk National University, Cheongju, Republic of Korea | Park, J.M., Chungbuk National University, Cheongju, Republic of Korea | Kim, M.J., Chungbuk National University, Cheongju, Republic of Korea | Kang, J.H., Chungbuk National University, Cheongju, Republic of Korea | Lee, S.W., Chungbuk National University, Cheongju, Republic of Korea | Kim, T.J., Chungbuk National University, Cheongju, Republic of Korea
A mannitol dehydrogenase (StMDH) gene was cloned from Salmonella typhimurium LT2 (KCTC 2421) and overexpressed in Escherichia coli. It has a 1,467 bp open reading frame encoding 488 amino acids with deduced molecular mass of 54 kDa, which shares approximately 36% of amino acid identity with known long-chain dehydrogenase/reductatse (LDR) family enzymes. The recombinant StMDH showed the highest activity at 30℃, and pH 5.0 and 10.0 for D-fructose reduction and D-mannitol oxidation, respectively. On the contrary, it has no activity on glucose, galactose, xylose, and arabinose. StMDH can catalyze the oxidative/reductive reactions between D-fructose and D-mannitol only in the presence of NAD+/NADH as coenzymes. These results indicate that StMDH is a typical NAD+/NADH-dependent mannitol dehydrogenase (E.C. 1.1.1.67).
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