Characterization of a thermostable mannitol dehydrogenase from hyperthermophilic Thermotoga neapolitana DSM 4359 with potential application in mannitol production

Publication date: Available online 11 October 2016 Source:Journal of Molecular Catalysis B: Enzymatic Author(s): Marwa Yagoub Farag Koko, Hinawi Abdo Mustafa Hassanin, Rebaone Letsididi, Tao Zhang, Wanmeng Mu Mannitol-2-dehydrogenase (MtDH) (E.C. 1.1.1.67) gene was cloned from Thermotoga neapolitana DSM 4359 and expressed in Escherichia coli BL21. The purified enzyme showed a predicted clear band of 36kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). K m and V max values for reduction of D-fructose to D-mannitol were 20mM and 200U mg-1 respectively. k cat for reduction direction was 180s−1 and k cat/K m were 9mM−1 s−1. The enzyme showed optimal pH at 6.5 and the optimum temperature was 90°C with 100% relative activity. The purified enzyme was quite stable at 75°C and had half of initial activity after 1h of incubation at 90°C. (TnMtDH) showed no activity with xylitol, inositol, sorbitol, rahmanose, mannose and xylose, and with NADPH and NADP+ as co factors. The presence of some divalent metals in the reaction enhanced the enzyme activity. The enzyme might be utilizing to produce mannitol without other sugar conformation under high temperature. Graphical abstract

Source: Journal of Molecular Catalysis B: Enzymatic - October 11, 2016 Category: Biochemistry Source Type: research