Non-enzymatic acetylation of human hemoglobins

Chromatographically purified Hb F0, Hb A0 and Hb S0 fractions were incubated with 70 microM [14C]acetyl-CoA for 3 h in 20 mM Tris-HCl, pH 7.6 and 8.6. The acid-precipitable radioactivity was monitored and the hemoglobins were separated by Biorex 70 chromatography. The pH dependence of acetylation showed an increase in acetylation with an increase in pH from 7.6 to 8.6, whereas an increase in ionic strength decreased acetylation. Incubation of Hb F0 with [14C]acetyl-CoA resulted in modified hemoglobin and gamma chains that co-chromatographed with Hb FIc and gamma 1c chains, respectively. Acetylation of Hb A0 and Hb S0 produced minor hemoglobins whose chromatographic mobilities were slightly faster than those of Hb AIc and Hb SIc, respectively, Radioactivity peaks also appeared at the leading edges of the major hemoglobin zones as well, which indicates that, like non-enzymatic glycosylation, non-enzymatic acetylation of hemoglobins involves both specific and nonspecific reactions.