Polyol Metabolism in Fungi

Abstract

Polyols (sugar alcohols) are widely distributed in fungi. They could serve several roles in living organisms: (1)act as carbohydrate reserves, (2) act as translocatory compounds, (3) function in osmoregulation, and (4) in coenzyme regulation and storage of reducing power. This chapter describes several enzymes that are concerned with polyol metabolism in fungi. These include Glycerol dehydrogenase (NAD + ), Glycerol-3-phosphate dehydrogenase (NAD + ), Xylitol dehydrogenase (NAD + ), Mannitol-1-phosphate dehydrogenase, Polyol dehydrogenase (NADP + ), Mannitol dehydrogenase (NAD + ), Glyceroldehydrogenase (NADP + ), Ribitol-5-phosphate dehydrogenase (NADP + ), Mannitold ehydrogenase(NADP + ), Glycerophosphate dehydrogenase, Glycerol kinase, Mannitol kinase, Mannitol-1-phosphatase, Sorbitol (glucitol) dehydrogenase, and Glycerol oxidase. A number of enzymes have relatively high K m , values for their substrates and a high pH optimum for the oxidation of polyols, which is likely to be a consequence of the buffer more effectively consuming protons at such pH values. It is conceivable that these particular enzymes are membrane-bound. The groups to which the various fungi belong are identified and designated as—namely, Mastigomycotina (M), Zygomycotina (Z), Ascomycotina (A), Deuteromycotina (D) and Basidiomycotina (B).