Aerobic decomposition of dimethylthiourea nitrosyl iron complex in the presence of albimin and glutathione

Abstract

Nitrosyl iron complexes (NICs) are natural “depots” of NO. NICs forms by the interaction of endogenous nitric oxide (NO) and non‒heme [2Fe-2S] proteins. Their synthetic analogues are promising compounds in medicines for the treatment of socially significant diseases. In this paper, the effect of bovine serum albumin (BSA) and reduced glutathione (GSH) on the decomposition of a nitrosyl iron complex with N,N′-dimethylthiourea ligands [Fe(SC(NHCH3)2)2(NO)2]BF4 (complex 1) under aerobic conditions have been investigated. In the absorption spectra complex 1 in the presence of albumin a wide band at 370–410 nm appears, which indicates the coordination of the aerobic decay product of the complex in the hydrophobic pocket of the protein with Cys34 and His39. The quenching of albumin intrinsic fluorescence during titration with complex 1 was studied by fluorescence spectroscopy. The Stern-Vollmer constant K = (2.3 ± 0.2) ∙ 105 М-1 and the Förster radius 22.4 Å were calculated. The UV-spectrum complex 1 in presence of GSH has two peaks at 312 and 363 nm, which respond glutathione binuclear NICs.