The Mechanism of Cytochrome C Reduction by Alkyl Radicals. Evidence for Multiple Reaction Pathways

Abstract

The reactions of the hydroxyalkyl radicals CH₂OH and (CH₃), COH with oxidized cytochrome c are far more complex than previously reported. Analysis of the pulse-radiolytic data by kinetic modelling revealed that only about 40% of the alkyl radicals reduce the ferric iron chromophore. Altogether. four different reactions have to be considered for the disappearance of the alkyl radicals. only two of which affect the metal site. The data show that these radicals. similar to the much more reactive hydrated electrons and hydrogen atoms. are capable to react with biological macromolecules in diverse ways.

Key Words:

• Methanol
• isopropanol
• hydroxyalkyl radicals
• pulse radiolysis
• rate constants
• kinetic modelling