UNIQUE ISOZYMES OF SUPEROXIDE-DISMUTASE IN STREPTOMYCES-GRISEUS

Two unique isozymes of superoxide dismutase (EC 1.15.1.1) were purifie d to apparent homogeneity from Streptomyces griseus by a purification procedure consisting of ammonium sulfate precipitation and chromatogra phies on DEAE: Sephacel, Sephacryl S-200, and DEAE 5PW. Superoxide dis mutase I was composed of four identical subunits of 13.0 kDa. The abso rption spectrum of superoxide dismutase I exhibited absorption bands a t 276 and 378 nm and a broad shoulder at 530 nm. The g values of elect ron paramagnetic resonance spectrum of superoxide dismutase I were g(1 ) 2.304, g(2) = 2.248, and g(3) = 2.012 and the resonance centered at g(3) = 2.012 was split into triplet, indicating nickel-containing supe roxide dismutase. Superoxide dismutase I contained 0.89 g-atom of nick el per mole of 13.0-kDa subunit. Superoxide dismutase II was composed of four identical subunits of 22.0 kDa. The absorption spectrum of sup eroxide dismutase II showed the featureless absorption band in the ran ge of 300-500 nm. The g values of electron paramagnetic resonance spec trum of superoxide dismutase II were g(z) = 4.762, g(x) = 4.072, and g (y) = 3.742, indicating iron-containing superoxide dismutase. Superoxi de dismutase II uniquely contains 0.40 g-atom of iron per mole of mono mer as well as 0.43 g-atom of zinc per mole of monomer. The immunologi cal cross-reactivity between two isozymes was not found. Nickel-contai ning superoxide dismutase was widely distributed within the genus Stre ptomyces; however, iron- and zinc-containing superoxide dismutase was not found in S. albus and S. longisporoflavus, on the basis of the imm unological cross-reactivity. (C) 1995 Academic Press, Inc.