Human red cell acetyltransferase.

Acetyltransferase was isolated by histone-Sepharose affinity chromatography from human cord blood red cells. The enzyme was detected only in very young red cells. The semipurified enzyme and [14C]acetyl-CoA were used to acetylate isolated Hb F tetramer and alpha and gamma subunits. The in vitro acetylated products were characterized by globin chain separation by CM-cellulose chromatography and tryptic peptide analysis by reverse-phase HPLC. Acetylation of both the gamma-chains and the alpha-chains could occur within the Hb F tetramer. Acetylation also could take place on intact subunits. It appears that some Hb FIC could be formed in the cells by utilizing Hb F or free gamma-chains as acetylation substrate.