Heterogeneity in the globin chain composition of a human minor fetal hemoglobin component.
The first hemoglobin found to contain an acetyl blocking group was the minor human fetal hemoglobin, Hb FI, present as 10-15% of the total fetal hemoglobin in umbilical cord blood red cells. Acetylation occurs at the amino-terminal glycine of the gamma-globin chain. Assays for the acetyl group by two different methods gave values less than the 2 per tetramer expected for a fully acetylated hemoglobin. We have purified acetylated fetal hemoglobin FIc to homogeneity. The globin chain composition of Hb FIc has been examined by both globin chain separation on CM-cellulose and by tryptic peptide mapping by HPLC. The identities of the gamma globin chains and of the gamma T-1 peptides were confirmed by amino acid analysis. Globin chain separation profiles showed the presence of 22.3 +/- 7.0% of gamma 0 globin (of the total gamma globin) in Hb FIc. Accordingly, the tryptic peptide maps of Hb FIc tetramers also showed the presence of a similar amount of gamma 0T-1 peptide. The gamma 0T-1 peptide was not present in the maps of isolated gamma Ic globin. It is evident that column purified Hb FIc contains a certain percentage of non-acetylated gamma-globin chains, thus indicating a hybrid globin chain composition for this minor fetal hemoglobin component.
Kasten-Jolly
J
J
Abraham
E C
EC
D000107:Acetylation; D005319:Fetal Hemoglobin / Q000302:isolation & purification; D005914:Globins / Q000302:isolation & purification; D006801:Humans; D007231:Infant, Newborn; D010446:Peptide Fragments / Q000302:isolation & purification; D011487:Protein Conformation
D010446:Peptide Fragments; D005914:Globins; D005319:Fetal Hemoglobin