Abstract
Nucleoside oxidase purified from Pseudomonas maltophilia LB-86 had mol. wt. = 130.000 and was composed of one each of four non-identical subunits: subunit α, 76, 000; subunit β, 33, 000; subunit γ, 18, 000; subunit δ, 14, 000. The enzyme contains 1 mol of covalently bound FAD, 2 g atoms of non-heme iron, 2 mol of labile sultides, and 1 mol of heme per mol enzyme protein. The absorption spectrum of nucleoside oxidase had maxima 278 and 390 nm, and shoulders at 343 and 450 nm.
The enzyme catalyzes the oxidation of various nucleosides, and the Km value for inosine was 4.4 × 10-5 M. The enzyme was most active at pH 5-6, and was most stable between pH 5.0-6.0 and at temperatures below 60°C. The activity was strongly inhibited by N-bromosuccinimide and potassium cyanide.
