NDLI: Thermotoga maritima TM0298 is a highly thermostable mannitol dehydrogenase

Content Provider	Springer Nature Link
Author	Song, Seung Hoon Ahluwalia, Nitasha Leduc, Yvonne Delbaere, Louis T. J. Vieille, Claire
Copyright Year	2008
Abstract	Thermotoga maritima TM0298 is annotated as an alcohol dehydrogenase, yet it shows high identity and similarity to mesophilic mannitol dehydrogenases. To investigate this enzyme further, its gene was cloned and expressed in Escherichia coli. The purified recombinant enzyme was most active on fructose and mannitol, making it the first known hyperthermophilic mannitol dehydrogenase. T. maritima mannitol dehydrogenase (TmMtDH) is optimally active between 90 and 100 °C and retains 63% of its activity at 120 °C but shows no detectable activity at room temperature. Its kinetic inactivation follows a first-order mechanism, with half-lives of 57 min at 80 °C and 6 min at 95 °C. Although TmMtDH has a higher V max with NADPH than with NADH, its catalytic efficiency is 2.2 times higher with NADH than with NADPH and 33 times higher with NAD+ than with NADP+. This cofactor specificity can be explained by the high density of negatively charged residues (Glu193, Asp195, and Glu196) downstream of the NAD(P) interaction site, the glycine motif. We demonstrate that TmMtDH contains a single catalytic zinc per subunit. Finally, we provide the first proof of concept that mannitol can be produced directly from glucose in a two-step enzymatic process, using a Thermotoga neapolitana xylose isomerase mutant and TmMtDH at 60 °C.
Starting Page	485
Ending Page	495
Page Count	11
File Format	PDF
ISSN	01757598
Journal	Applied Microbiology and Biotechnology
Volume Number	81
Issue Number	3
e-ISSN	14320614
Language	English
Publisher	Springer-Verlag
Publisher Date	2008-08-22
Publisher Place	Berlin, Heidelberg
Access Restriction	Subscribed
Subject Keyword	Thermotoga maritima Mannitol dehydrogenase Thermostable enzyme Mannitol Glucose Fructose Microbial Genetics and Genomics Microbiology Biotechnology
Content Type	Text
Resource Type	Article
Subject	Medicine Applied Microbiology and Biotechnology Biotechnology

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