[Mono- and Binuclear Dinitrosyl Iron Complexes with Thiol-containing Ligands in Various Biosystems].

It has been shown that dinitrosyl iron complexes with thiol-containing ligands that are bound with modified bovine serum albumin with a large number of thiol groups that occurred in baker yeast or in animal tissues in the presence of exogenous or endogenous nitric oxide, respectively, consist predominantly of the EPR-silent binuclear form. This form can be transformed into the EPR-active mononuclear form of dinitrosyl iron complexes with an increase in the pH to basic values, into the EPR-active form of mononuclear iron nitrosyl complexes in the case of two-electron reduction of the binuclear form of dinitrosyl iron complexes or under the action of dithiocarbamate derivatives. The latter process induced the transformation of dinitrosyl iron complexes into EPR-active mononitrosyl iron complexes with dithiocarbamates. The significant number of binuclear dinitrosyl iron complexes with thiol-containing ligands in living systems and the similar biological effects of these complexes and the system of endogenous nitric oxide allow us to consider endogenous binuclear dinitrosyl iron complexes as a “working form” of endogenous nitric oxide, which is now recognized as a universal regulator of biological processes.