The Primary Structure of the Hemoglobin of the Dogfish Shark(Squalus acanthias).Antagonistic Effects of ATP and Urea on Oxygen Affinity of an Elasmobranch Hemoglobin

Abstract
The amino-acid sequence of the Hb of the dogfish shark (Squalus acanthias) is presented. The .alpha.-chains consist of 141 residues and show a Thr/Ser ambiguity at position 3. The .beta.-chains consist of 142 residues and evidently have no D-helix; they show an Asn/Tyr ambiguity at position 104. Both chains have free N-terminal amino acids. The phylogenetic distance from the human .alpha.- and .beta.-chains is indicated by 49.3% and 56.2% amino-acid exchanges. The primary structure is discussed in relation to the oxygen-binding properties of elasmobranch Hb, particularly as regards the antagonistic effects of urea and ATP, and the effects of proton concentration (the alkaline and acid Bohr effects, and the Root effect).

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