The Primary Structure of the Hemoglobin of the Mole Rat(Spalax ehrenbergi,Rodentia, Chromosome Species 60)

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Abstract
Mole rat (S. ehrenbergi) Hb consists of only 1 component. The complete amino-acid sequence of the .alpha.- and .beta.-chains of the species with the diploid chromosome number of 60 is presented. Following chain separation by chromatography on carboxymethyl cellulose CM-52, the primary structures were established by automatic Edman degradation on the chains, on the tryptic peptides and on a peptide obtained by acid hydrolysis of the Asp-Pro bond in .beta.-chains. The alignment of the peptides was performed by homology with human .alpha.- and .beta.-chains. The comparison showed an exchange of 23 residues in the .alpha.-chains and 26 in the .beta.-chains. One substitution in the .beta.-chains concerns the surrounding of the heme. Two exchanges in each chain in the .alpha.1.beta.1-subunit interface and 1 in the .beta.-chain .alpha.1.beta.2-contact points. Though all binding sites for 2,3-bisphosphoglycerate are unchanged, the mole rat blood has a high O2 affinity as a part of adaptation to subterranean life under hypoxia and hypercapnia. A comparison of the sequence with known X-ray models of Hb may give an interpretation of this fact. The primary structure of the mole rat Hb shows more similarities with surface rodents, than with the mole, another small mammal, adapted to hypoxia in subterranean tunnels. The adaptation to hypoxia in mole rat and mole must be due to different mechanisms.