Hämoglobine, XLVII. Das Hämoglobin der Streifengans(Anser indicus). Primärstruktur und Physiologie der Atmung, Systematik und Evolution

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Abstract
The primary structures of the .alpha.- and .beta.-chains of the main component of bar-headed goose (A. indicus) are given. By homologous comparison with the Hb of the gray-lag goose (A. anser), 3 differences were found in the .alpha.-chains and 1 difference in the .beta.-chains. In position .alpha.119 H2Ala and .beta.125 H3Asp, .alpha.1.beta.2-contact points are changed. The mutation .alpha.63 E12Val brings a drastic change in tertiary structure of the .alpha.-chains of bar-headed goose: the helices E and B are moved apart by 1.5 .ANG. as there is no room for the larger side chain. This is probably the reason for a slightly higher intrinsic O2 affinity of bar-headed goose Hb. The bindings of inositol pentaphosphate on Hb are identical in gray-lag goose and bar-headed goose (contact points are not mutated). The reason for the increased difference in O2 affinity by binding of inositol pentaphosphate is probably caused by 2 mutations in .alpha.1.beta.2-contact points. These 2 mutations are apparently the reason for a different interaction between .alpha.- and .beta.-chains under the influence of inositol pentaphosphate by gray-lag and bar-headed goose Hb. The difference in the primary structure of the gray-lag and bar-headed goose Hb suggests that the bar-headed goose is not the genus of Anser. Unfinished experiments (.apprx. 80% of the sequences) of white-fronted goose (A. albifrons albifrons) and snow goose (A. caerulescens caerulescens) show no exchanges with gray-lag goose Hb. The Canada goose (Branta canadensis), however, which belongs to the genus Branta has a number of substitutions similar to the bar-headed goose Hb. These changes in primary structure suggest that gray-lag goose and bar-headed goose are separated by a period of 9-15 million yr. The 2 species of goose evidently became geographically separated by the elevation of the Himalayas.

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