Features of the decomposition of thiosulfate nitrosyl iron complex in the presence of hemoglobin and cytochrome c

Abstract

Nitrosyl complexes of non-heme iron (NICs) are the depot of nitric monoxide (NO) in the body. They nitrosylate heme-containing proteins in the process of decomposition. In this work, we studied the interaction of the thiosulfate complex Na2[Fe2(S2O3)2(NO)4]·4H2O (complex 1), as a promising drug agent, with hemoglobin and cytochrome c. It was found that complex 1 and its decomposition products are adsorbed on the surface of oxyhemoglobin, leading to longer NO generation compared to an aqueous buffer solution. In the system with metHb, the accumulation of the product (nitrosyl hemoglobin) occurs only under anaerobic conditions.The article also presents experimental data on the nitrosylation of ferro- and ferricytochrome c (cyt c2+ and cyt c3+, respectively) in the presence of complex 1. Cyt c2+ forms the product (NO)cyt c2+, which serves as the “depot” form of NO. This protein has a lesser stabilizing effect on complex 1 compared to hemoglobin. In the system with cyt c3+, nitrosylation of protein occurs during mixing, due to the presence of an oxidizing agent K3[Fe(CN)6].