Increased glutathionyl hemoglobin in diabetes mellitus and hyperlipidemia demonstrated by liquid chromatography/electrospray ionization-mass spectrometry

Background: Erythrocytes contain a large amount of glutathione (GSH), which protects cells from oxidative injury. The purpose of this study was to exa mine whether hemoglobin (Hb) is modified with glutathione by oxidation of t he thiol groups in diabetes mellitus and hyperlipidemia, and to determine t he oxygen affinity of glutathionyl Hb, Methods: Hb samples obtained from patients with type 2 diabetes, patients w ith hyperlipidemia,and healthy subjects were analyzed by liquid chromatogra phy/electrospray ionization-mass spectrometry (LC/ESI-MS). Glutathionyl Hb was synthesized in vitro by incubating Hb with GSH, The oxygen affinity of glutathionyl Hb was determined by measuring its oxygen dissociation curve. Results: We first demonstrated that the concentration of glutathionyl Hb be ta chains is markedly increased in the diabetic patients and hyperlipidemic patients compared with healthy subjects. The in vitro synthesis of glutath ionyl Hb by incubation of Hb with GSH was enhanced by adding H2O2, a reacti ve oxygen species, into the incubation solution. The glutathionyl Hb prepar ed in vitro by incubating Hb with GSH showed a marked increase in oxygen af finity and a marked decrease in the Hill coefficient compared with Hb incub ated without GSH. Conclusions: Glutathionyl Hb may be useful as a clinical marker of oxidativ e stress. The increased concentrations of glutathionyl Hb with high oxygen affinity and low cooperativity in diabetes and hyperlipidemia may lead to r educed tissue oxygen delivery, (C) 2000 American Association for Clinical Chemistry.