Hydroperoxide-dependent folic acid degradation by cytochrome c.

Folic acid is degraded by cytochrome c in the presence of hydrogen peroxide/tert-butyl hydroperoxide at the C9-N10 bond. The degradation is increased with increasing temperature. When guanidine HCl or benzoate are included in the reaction medium, the amount of folic acid degradation is enhanced. Catalase, formate, and thiourea inhibited hydrogen peroxide-dependent folic acid degradation only, and not tert-butyl hydroperoxide dependent degradation. Cyanide and azide markedly inhibited both the hydroperoxide-dependent degradations. Superoxide dismutase, EDTA, ethanol, mannitol, and dimethyl sulfoxide did not inhibit the degradation. The mechanism of cytochrome c-catalyzed folic acid degradation is discussed.