cytochrome-c-t and ferryl-iron

The peroxidase-type reactivity of cytochrome c is proposed to play a role in free radical production and/or apoptosis. This study describes cytochrome c catalysis of peroxide consumption by ascorbate. Under conditions where the sixth coordination position at the cytochrome c heme iron becomes more accessible for exogenous ligands (by carboxymethylation, cardiolipin addition or by partial denaturation with guanidinium hydrochloride) this peroxidase activity is enhanced. A reaction intermediate is detected by stopped-flow UV-vis spectroscopy upon reaction of guanidine-treated cytochrome c with peroxide, which resembles the spectrum of globin Compound II species and is thus proposed to be a ferryl species. The ability of physiological levels of ascorbate (10-60 µM) to interact with this species may have implications for mechanisms of cell signalling or damage that are based on cytochrome c/peroxide interactions.

Topics: Animals; Apoptosis; Ascorbic Acid; Cardiolipins; Cattle; Cytochrome-c Peroxidase; Cytochromes c; Free Radicals; Guanidine; Heme; Horses; Hydrogen Peroxide; Iron; Kinetics; Methylation; Mitochondria, Heart; Signal Transduction; Spectrum Analysis; Yeasts