The Primary Structure and Functional Properties of the Hemoglobins of a Ground Squirrel(Spermophilus townsendii,Rodentia)

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Abstract
The hemoglobin of the ground squirrel Spermophilus townsendii consists of two components which are present in a ratio of ca. 2:1. The two hemoglobins have identical .alpha.-chains, but differ in their .beta.-chains. We present the primary structures of the .alpha.- and the two .beta.-globin chains. Following chain separation by chromatography on carboxymethyl-cellulose CM-52, the amino-acid sequences were established by automatic Edman degradation of the globin chains and the tryptic peptides, as well as of a peptide obtained by acid hydrolysis of the Asp-Pro bond of the .beta.-chains. The two .beta.-chains differ by only one amino-acid residue, Ala being present in the main and Asp in the minor component in position 58 (E2). The comparison with human hemoglobin showed only 14 exchanges in the .alpha.-chains but 33 in the .beta.-chains. Whereas no contact positions are affected in the .alpha.-chains, we found four such substitutions in the .beta.-chains, including one heme contact, two .alpha.1/.beta.1-contacts, and one .alpha.1/.beta.2-contact. It seems however, that the substitution found in the .beta.-chains has no effect on the oxygen affinity.