The primary structure of the hemoglobin of the Cormorant (Phalacrocorax carbo, Pelecaniformes)

The erythrocytes of the adult Cormorant contain two hemoglobin components in a ratio of 83% Hb A to 17% Hb D. The primary structures of the alpha A-, alpha D- and beta-chains are presented. The globin chains were separated by high-performance liquid chromatography and cleaved enzymatically and/or chemically. The native chains and their fragments were sequenced using liquid- or gas-phase sequencers, and the peptides aligned using the homology to human and to avian hemoglobin sequences. Compared to human hemoglobin, there are 46 amino-acid replacements in the alpha A-chains (67.4% homology), 65 replacements in the alpha D-chains (53.9% homology) and 45 replacements in the beta-chains (69.2% homology). In the functionally important regions, the percentage of amino-acid substitutions, as compared to human hemoglobin, is 13.2% in the alpha A-, 19.0% in the alpha D - and 16.0% in the beta-chains. The importance of the replacement beta 135 arginine (other birds)----glycine (Cormorant) in the phosphate-binding pocket and its effect on phosphate binding will be discussed.