Degradation of linoleic acid hydroperoxides by a cysteine . FeCl3 catalyst as a model for similar biochemical reactions. I. Study of oxygen requirement, catalyst and effect of pH.

摘要: Abstract 1. A redox reaction between cysteine and linoleic acid hydroperoxide was catalyzed by FeCl3 at pH values under 6. This assayed the rate of O2 uptake, resulted in formation mainly oxodiene, epoxyhydroxyene epoxyoxoene fatty acids as well cystine oxides cysteine. 2. The uptake dependent upon relative concentrations FeCl3, Rate dependence on concentration yielded a sigmoid curve, but either or best described Lineweaver-Burk double reciprocal plot. possible participation hydroperoxide-cysteine-FeCl3 complex is discussed. 3. About one-half mol absorbed per hydroperoxide, whereas amounted to one-fourth mol. mechanism proposed account for stoichiometry. 4. In presence O2, products were oxooctadecadienoic derived from addition an epoxyallylic radical (secondary hydroperoxidation). absence cysteine-fatty adducts. 5. Either Fe(II) Fe(III) salts equally effective catalysts, CN− EDTA complexes iron ineffective catalysts. At over 7 hydroxyoctadecadienoic became only product formed hydroperoxide. Hydroxydiene O2. Only alkaline essential hydroxydiene formation. 7. 7, O2− ascertained Superoxide dismutase-inhibitable nitroblue tetrazolium reduction. Rationale presented that not involved 8. served model degradation certain biological preparations.