Reductive Nitrosylation of Hemoglobin and Myoglobin and its Antioxidant Effect

Angeli’s salt is a nitroxyl donor, due to which it can prevent the negative consequences of hemolysis, such as the vasoconstrictive effect of free hemoglobin in blood plasma. However, the molecular mechanisms of the interaction of nitroxyl with various hemoproteins have not been sufficiently elucidated. It is known that oxoferryl forms of hemoproteins arising from oxidative stress are strong prooxidants. In this study, the reductive nitrosylation of meth- and oxoferryl forms of hemoglobin and myoglobin with nitroxyl was investigated. The experiments were carried out in vitro by detecting nitrosyl forms of hemoproteins using electron paramagnetic resonance spectroscopy. The results indicate the antioxidant effect of Angeli’s salt in systems simulating the oxidation of hemoglobin or myoglobin by hydrogen peroxide. As well, the addition of hydrogen peroxide to hemoglobin and myoglobin metforms led to the appearance of an EPR signal of free radicals with g = 2.005 associated with the protein part of these hemoproteins. Thus, nitroxyl acted simultaneously as a reducing and nitrosylating agent, thereby preventing the formation of oxoferryl forms of hemoproteins. The therapeutic properties of Angeli’s salt may be largely related to the antioxidant effect exerted on blood components.