[Hemoglobins, XLVII. Hemoglobins of the bar-headed goose (Anser indicus): primary structure and physiology of respiration, systematic and evolution].

The primary structures of the alpha- and beta-chains of the main component of Bar-headed Goose (Anser indicus) are given. By homologous comparison with the hemoglobin of the Grey-Lag Goose (Anser anser) 3 differences were found in the alpha-chains, 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 A as there is no room for the larger side chain. This is probably the reason for a slightly higher intrinsic oxygen affinity of Bar-headed Goose hemoglobin. The bindings of inositol pentaphosphate on hemoglobin are identical in Grey-Lag Goose and Bar-headed Goose (contact points are not mutated). The reason for the increased difference in oxygen affinity by binding of inositol pentaphosphate is probably caused by two mutations in alpha 1 beta 2-contact points. It suggests that these two mutations are the reason for a different interaction between alpha- and beta-chains under the influence of inositol pentaphosphate by Grey-Lag and Bar-headed Goose hemoglobins. The difference in the primary structure of the Grey-Lag and Bar-headed Goose hemoglobins suggests that the Bar-headed Goose is not the genus of anser. Unfinished experiments (about 80% of the sequences) of White-fronted Goose (Anser albifrons a.) and Snow Goose (Anser caerulescens c.) show no exchanges with Grey-Lag Goose hemoglobin. The Canada Goose (Branta canadensis), however, which belongs to the genus Branta, has a number of substitutions similar to the Bar-headed Goose hemoglobin. These changes in primary structure suggest that Grey-Lag Goose and Bar-headed Goose are separated by a period of 9-15 Million years. This would support the hypothesis that the two species of goose became geographically separated by the elevation of the Himalayas.