Interaction of Hemoglobin with Binuclearcationic Tetranitrosyl Iron Complex with Penicillamine. Cations Binding Sites

Abstract

In this paper, the kinetics of the interaction of the nitrosyl iron complex with the ligands penicil-lamine [Fe 2 (SC 5 H 11 NО 2) 2 (NO) 4 ]SO 4 • 5H 2 O (I) with deoxyhemoglobin (Hb) was studied. The kinetic modeling method defined the number of binding (I) molecules and equilibrium constant of the coupling reaction of (I) with Hb (K s). At equimolar concentrations of (I) and Hb (2 × 10 −5 M), the Hb molecule binds only one (I) with K s equal to 4.3 × 10 7 M −1 . When increasing the (I) concentration, the number of binding sites of Hb increases and K s decreases. These results are analyzed in accor-dance with the data on the existence of cations binding sites in Hb.