Sorbitol dehydrogenase, microorganism for producing same, process for the production thereof, method for the measurement of sorbitol and reagent for the quantitative determination therefor

A sorbitol dehydrogenase having the following physicochemical properties:

• (1) activity:
• the sorbitol dehydrogenase catalyzes dehydrogenation oxidation of D-sorbitol in the presence of NAD+ to produce D-fructose, and catalyzes a reverse reaction which reduces D-fructose in the presence of NADH to produce D-sorbitol and NAD+;
• (2) substrate specificity:
• the sorbitol dehydrogenase exhibits a Vmax/Km value of about 40 or less for galactitol and about 3 or less for L-iditol when the Vmax/Km value for D-sorbitol is taken as 100, and which does not act on D-arabitol, D-mannitol, xylitol and D-glucose;
• and
• (3) exhibits a Km value of about 6 mM or less with respect to D-sorbitol.