Nucleoside oxidase, a hydrogen peroxide-forming oxidase, from Flavobacterium meningosepticum

Abstract

A novel enzyme which catalyzes the oxidation of nucleosides to nucleoside-5'-carboxylic acids, forming hydrogen peroxide, was purified to homogeneity from Flavobacterium meningosepticum T-2799. The enzyme has a molecular weight of about 500,000, and four nonidentical subunits (molecular weights of 81,000, 69,000, 33,000, and 16,000) were detected on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. On the basis of visible absorption spectra of the purified enzyme, the enzyme is concluded to be a hemoprotein. It also contains covalently bound flavin adenine dinucleotide. The various nucleosides, such as adenosine (K(m) = 48 μM), inosine (K(m) = 66 μM), guanosine (K(m) = 21 μM), thymidine (K(m) = 50 μM), uridine (K(m) = 80 μM), and cytidine (K(m) = 50 μM), were oxidized by the enzyme, but nucleotides, bases, and ribose were not.