A note comparing the primary structure of hemoglobin β chains of the arctic ground squirrel and the yellow-bellied marmot

Hemoglobin β chains were isolated from both the arctic ground squirrel (Citellus parryii undulatus) and the yellow-bellied marmot (Marmota flaviventris). After various enzymatic and chemical cleavages, the primary structures of these β chains were determined. Only one sequence difference was found between the yellow-bellied marmot β chain and that of the European marmot (Marmota marmota). Ground squirrels (C. p. undulatus, Citellus townsendii, and Citellus citellus) showed more species-related differences than the marmots, with the β chain of the arctic ground squirrel differing from that of the townsend ground squirrel by four amino acid substitutions. In the amino terminal region of the β chain, a partial sequence analysis showed that Citellus tridecemlineatus was more similar to C. p. undulatus than to C. townsendii. These biochemical differences could reflect either an increased evolutionary rate of speciation in ground squirrels over that in the genus Marmota or a more recent origin of the species in the genus Marmota. The amino acid differences between these hemoglobins do not appear to be functionally significant in these ecologically similar animals.