[Thiol-dependent generation of superoxide radical induced by menadione and vicasol]

It was demonstrated that in the presence of blood serum menadione and vicasol reduce cytochrome c in two ways, i. e., via O2-. -dependent and O2-. -independent routes. T ability of the serum to generate O2-. in the presence of menadione is retained after dialysis. Albumin can also act as an electron donor during O2-. generation mediated by menadione; however, this ability of the serum does not correlate with the presence of albumin in it. N-Ethylmaleimide and Cu2+ inhibit the ability of albumin and blood serum to induce menadione-mediated generation of O2-. It is concluded that in the presence of thiol-containing proteins and O2-. vitamin K3 forms an oxidative system generating O2-.