Globins Scavenge Sulfur Trioxide Anion Radical.

摘要: Ferrous myoglobin was oxidized by sulfur trioxide anion radical (STAR) during the free chain oxidation of sulfite. Oxidation inhibited STAR scavenger GSH and heme ligand CO. Bimolecular rate constants for reaction with several ferrous globins biomolecules were determined kinetic competition. Reaction myoglobin, hemoglobin, neuroglobin, flavohemoglobin are large at 38, 120, 2,600, ≥ 7,500 × 10(6) m(-1) s(-1), respectively, correlate redox potentials. Measured O2, GSH, ascorbate, NAD(P)H also ∼100, 10, 130, 30 but nevertheless allow favorable competition a capacity scavenging in vivo. Saccharomyces cerevisiae lacking sulfite oxidase deleted showed an O2-dependent growth impairment nonfermentable substrates that exacerbated sulfide, precursor to mitochondrial formation. Higher O2 exposures inactivated superoxide-sensitive aconitase cells, hypoxia elicited both NADP(+)-isocitrate dehydrogenase activity losses. Roles STAR-derived peroxysulfate radical, superoxide sulfo-NAD(P) mechanism toxicity protection yeast suggested.