Enhancement of S-Nitrosylation in glycosylated hemoglobin

In this study, we report a novel differential nitric oxide interaction with nonglycosylated and glycosylated hemoglobin. After in vitro incubation of hemoglobin with S-nitroso N-acetyl penicillamine (SNAP), s-nitrosoglutathio ne, or S-nitrosocysteine, S-nitrosylation was significantly higher in human glycosylated hemoglobin purified from diabetic subjects compared to nondia betic controls. Inversely, spontaneous decomposition was significantly lowe r for S-nitrosohemoglobin obtained from glycosylated hemoglobin. Bidimensio nal isoelectric focusing of hemoglobins incubated in vitro with SNAP also r evealed a greater interaction of nitric oxide with glycosylated hemoglobin. In addition, a significantly higher level of S-nitrosohemoglobin was found in erythrocyte lysates from streptozotocin-induced diabetic rats compared to control Fats. We suggest that highly glycosylated hemoglobin in diabetic subjects may favor S-nitrosylation, which may in turn impair vascular func tion, and participate in diabetic microangiopathy. (C) 2000 Academic Press.