Carbamylation of the Chains of Hemoglobin S by Cyanate in Vitro and in Vivo

Abstract

Carbamylation of the NH2-terminal valine residues of hemoglobin by cyanate in vitro is about 2½ times as extensive in partially deoxygenated whole blood (40 to 50% oxygen saturation) as in fully oxygenated whole blood. When the carbamylated α and β chains of deoxyhemoglobin are separated, analyses show that the ratio of carbamylation is about 1.7:1 in favor of the α chain, whereas in fully oxygenated hemoglobin the ration is 1:1. The distribution of carbamyl groups on the hemoglobin chains prepared from the blood of patients on oral cyanate therapy suggests that carbamylation in vivo takes place predominantly with the deoxygenated protein.