Amino acid sequences of the epsilon and alpha E globins of HbE, a minor early embryonic hemoglobin of the chicken.

We have determined amino acid sequences for the alpha-like and beta-like globin components of HbE, one of the two minor hemoglobins in early chick embryos. The complete primary structure of the epsilon chain differs at 18 positions from the adult chicken beta globin, but there are no changes in heme-binding residues, alpha 1 beta 2 contact positions, or allosteric regulatory sites. By amino acid sequence analysis, we have identified a new alpha-like globin that we have called alpha E. The alpha E globin chain differs from the major adult alpha A chain at 22 amino acid positions. This paper discusses the structural and implied functional characteristics of these globins and presents hypotheses regarding the possible role of minor embryonic hemoglobins.