THE HEMOGLOBINS OF THE COLD-ADAPTED ANTARCTIC TELEOST CYGNODRACO MAWSONI

Abstract The blood of the teleost Cygnodraco mawsoni , of the endemic Antarctic family Bathydraconidae, contains a major hemoglobin (Hb 1), accompanied by a minor component (Hb 2, about 5% of total). The two hemoglobins have identical α chains and differ by the β chain. The complete amino acid sequence of the three chains has been elucidated, thus establishing the primary structure of both hemoglobins. The sequences show a 53–65% identity with non-Antarctic poikilotherm fish species; on the other hand, a very high degree of similarity (83–88%) has been found between Hb 1 and the major component of another Antarctic species of a different family. The hemoglobin functional properties relative to oxygen binding have been investigated in intact erythrocytes, ‘stripped’ hemolysate and purified components of C. mawsoni . The hemoglobins display the Bohr and Root effects, indicating fine regulation of oxygen binding by pH and by the physiological effectors organic phosphates.