2-Nitropropane Dioxygenase from Hansenula mrakii : Re-characterization of the Enzyme and Oxidation of Anionic Nitroalkanes

Abstract

2-Nitropropane dioxygenase, purified to homogeneity by an improved method from a yeast, Hansenula mrakii, has a molecular weight of 42, 000, and consists of a single polypeptide. The enzyme contains 1 mol of FAD per mol of enzyme. The iron protein associated with previous preparations was removed by the present purification procedures. The enzyme catalyzes the oxygenative denitrification of anionic nitroalkanes much more effectively than that of the neutral ones with the optimum pH of 6.5. The Michaelis constants for the anionic substrates are as follows : 2-nitropropane, 1.61mM; 1-nitropropane, 3.23mM; nitroethane, 3.13mM, and 3-nitro-2-butanol, 0.59mM.