Biochemical characteristics of erythrocyte sorbitol dehydrogenase from selected mammals.

The erythrocyte sorbitol dehydrogenase (EC 1.1.1.14) activity, regarding its action on sorbitol oxidation to fructose, was studied in 19 species of mammals, showing a striking variability, with high activity in rodents. Enzyme activity was studied against other polyols, namely xylitol, inositol, manitol and dulcitol. Most animals showed activity against all the polyols studied, but hamster and red deer only presented activity on sorbitol and xylitol. Michaelis-Menten constant determinations for sorbitol were performed, and it was observed that animals which presented high activity had a high Km. pH curves were obtained from 8 animals, with an optimum pH ranging from pH 8.0 to pH 10.0; four of the animals presented an optimum pH at 8.5.