Prevention by 3-N-ribosyluric acid of the oxidation of bovine hemoglobin by sodium nitrite.

The addition of sodium nitrite to washed bovine erythrocytes incubated in buffered saline resulted in the formation of methemoglobin with a decrease in the concentration of 3-N-ribosyluric acid. The oxyhemoglobin in hemolysates prepared from bovine red cells which contained high concentrations of 3-ribosyluric acid was oxidized to methemoglobin more slowly than oxyhemoglobin from cells with low levels of 3-ribosyluric acid. Oxyhemoglobin from hemolysates that were dialyzed was oxidized more rapidly than oxyhemoglobin which was not dialyzed. 3-Ribosyluric acid, glutathione, uric acid, and ascorbic acid prevented the oxidation of oxyhemoglobin by nitrite. Uric acid protected oxyhemoglobin at the lowest concentration, followed closely by ascorbic acid, 3-ribosyluric acid, and glutathione. Hydrogen peroxide enhanced the oxidation produced by nitrite; this effect was also prevented by the four antioxidants used.