I. Purification, Assay, and General Properties of the Enzyme*

In a study of the mechanism of action of notatin, the flavin adenine dinucleotide-dependent glucose aerodehydrogenase of molds, Bentley and Neuberger (2) in 1949 obtained evidence suggesting that the enzyme preparation also catalyzed the mutarotation of glucose. Keilin and Hartree (3, 4) demonstrated that some notatin samples contained a second enzyme, named mutarotase, which was the most active catalyst known for the mutarotation of glucose. A partial separation from notatin was achieved by precipitation with ammonium sulfate. Levy and Cook (5) studied the specificity of mutarotase and found that the mutarotation of n-galactose was accelerated almost as much as that of n-glucose. In 1954, Keston (6) observed that mutarotase preparations could be obtained from animal sources; Dgalactose, n-xylose, and L-arabinose were also substrates and the enzyme was inhibited by phlorizin. The present paper describes the assay and purification of highly active mutarotase from the culture fluids of Pencillium not&urn.