POLYOL DEHYDROGENASES OF AZOTOBACTER AGILIS

Marcus, Leon (University of California, Davis),and Allen G. Marr . Polyol dehydrogenases ofAzotobacter agilis . J. Bacteriol.82: 224–232. 1961.—Two soluble diphosphopyridine-linked polyol dehydrogenases are formed byAzotobacter agilis (A. vinelandii ). The first,d -mannitol dehydrogenase is induced byd -mannitol and all of the pentitols exceptl -arabitol. Ribitol is an excellent inducer of mannitol dehydrogenase although it is not metabolized, nor does the enzyme act upon it. This allows study of the gratuitous induction of mannitol dehydrogenase.Of the polyols tested, mannitol dehydrogenase oxidizesd -mannitol,d -arabitol,d -rhamnitol, and perseitol, demonstrating its requirement for substrates bearing thed -manno configuration. The corresponding 2-ketoses,d -fructose,d -xylulose, and presumablyd -rhamnulose, and perseulose are reduced.The second enzyme,l -iditol dehydrogenase is induced only by polyols containing thed -xylo configuration, i.e., sorbitol and xylitol.l -Iditol dehydrogenase oxidizesd -xylo polyols seven times faster than it doesd -ribo polyols. Substrates oxidized includel -iditol, sorbitol, xylitol, and ribitol. The corresponding 2-ketoses,l -sorbose,d -fructose,d -xylulose, andd -ribulose, are reduced.The two polyol dehydrogenases have been separated and purified by chromatography on a modified cellulose ion exchanger.