Prosimian hemoglobins. III. The primary structures of the duplicated alpha-globin chains of Lemur variegatus

The amino acid sequences of the alpha chains of hemoglobins purified from Lemur variegatus erythrocytes have been determined. The sequences were determined primarily from peptides generated from treatment of the isolated alpha chains with cyanogen bromide or warm formic acid. The ordering of the peptides from both alpha globins was based on the homology between lemur hemoglobins and those of other primates. The genetic difference at position 15 (Asn vs. Lys) explains the phenotypic characteristic of two hemoglobin species during alkaline electrophoresis. The function of certain residues is discussed in the context of other known sequences. The dispersion of the amino acid changes noted in lemur species falls mostly within the first 75 residues of the alpha chain (exons 1 and 2). The extent of divergence of the L. variegatus alpha-globin chains from the Lemur fulvus alpha globin is similar to that seen for the beta-globin chains of these species. This degree of separation (11-16 residues) is consistent with an extended period of independent evolution by these congeneric species after their divergence.