Purification and characterization of mannitol dehydrogenase from Aspergillus parasiticus

Abstract

Mannitol dehydrogenase, NADP specific (EC 1.1.1.138), was purified from mycelium of A. parasiticus (1-11-105 Whl). The enzyme had a molecular weigh of 1.4x105 and was composed of four subunits of apparently equal size. The substrate specificity was limited to D-mannitol, D-glucitol, D-arabinitol, 1-deoxy-D-mannitol, and 1-deoxy-D-glucitol. Zinc ion was a powerful inhibitor of the enzyme, inhibition being competitive with respect to mannitol, with K(i) about 1 μM. It is proposed that the stimulation of polyketide synthesis by zinc ion may be mediated in part by inhibition of mannitol dehydrogenase.