title: The expression of alpha D-chains in the hemoglobin of adult ostrich (Struthio camelus) and American rhea (Rhea americana). The different evolution of adult bird alpha A-, alpha D- and beta-chains.
abstract: The hemoglobin of adult American rhea (Rhea americana) and ostrich (Struthio camelus) contains two components identified to be HbA (alpha 2A beta 2) and HbD (alpha 2D beta 2). The amino-acid sequence of alpha D-chains from HbD of adult American rhea and ostrich has been determined. The sequence was studied by Edman degradation of tryptic peptides and chemical cleavage products in a liquid phase sequencer. By homologous comparison with pheasant HbD (Phasianus colchicus colchicus), the alpha D-chains of American rhea differ by 28 amino-acid exchanges, the alpha D-chains of ostrich by 23 residues. These differences are higher than those observed for alpha A- as well as for beta-chains of HbA from the same species. The ratio of amino-acid exchanges for beta:alpha A:alpha D for American rhea and ostrich is found to be 1:5.5:6.5. At present the reason for the differences in evolution rates for the beta-, alpha A- and alpha D-chains of bird hemoglobins is still unclear.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000097:blood*; D006441:Hemoglobin A / Q000032:analysis*; D006454:Hemoglobins / Q000032:analysis*; D006455:Hemoglobins, Abnormal / Q000032:analysis*; D046911:Macromolecular Substances; D010446:Peptide Fragments / Q000032:analysis; D013045:Species Specificity; D014357:Trypsin / Q000378:metabolism
chemical_list: D006454:Hemoglobins; D006455:Hemoglobins, Abnormal; D046911:Macromolecular Substances; D010446:Peptide Fragments; C032001:hemoglobin D; D006441:Hemoglobin A; D014357:Trypsin