title: Purification and physicochemical properties of superoxide dismutase from two photosynthetic microorganisms.
abstract: Superoxide dismutase (EC 1.15.1.1) has been isolated and characterised from the blue-green alga Spirulina platensis and from aerobically-grown Rhodopseudomonas spheroides, a purple, non-sulphur bacterium. The former enzyme contains 1 gatom of iron and the latter 1 gatom of manganese per mol; both enzymes have a molecular weight of 37 000-38 000, being composed of two non-covalently joined subunits of equal size. Various spectral studies have been carried out including absorbance, circular dichroism and electron spin resonance. Catalytic activity has been studied as a function of pH and shows a decrease at alkaline pH values. The manganoenzyme is generally more stable to various potentially denaturing conditions and is resistant to inactivation by hydrogen peroxide. Amino acid compositions and N-terminal residue determinations are presented.
mesh_terms: D000332:Aerobiosis; D000596:Amino Acids / Q000032:analysis; D001419:Bacteria / Q000201:enzymology*; D002942:Circular Dichroism; D004355:Drug Stability; D007501:Iron / Q000032:analysis; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism; D008345:Manganese / Q000032:analysis; D008970:Molecular Weight; D010788:Photosynthesis; D011487:Protein Conformation; D012242:Rhodobacter sphaeroides / Q000201:enzymology*; D013045:Species Specificity; D013056:Spectrophotometry, Ultraviolet; D013482:Superoxide Dismutase / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D000596:Amino Acids; D007527:Isoenzymes; D008345:Manganese; D007501:Iron; D013482:Superoxide Dismutase