We have determined the crystal structure of bar-headed goose haemoglobin in the oxy form to a resolution of 2.0 A. The R-factor of the model is 19.8%. The structure is similar to human HbA, but contacts between the subunits show slightly altered packing of the tetramer. Bar-headed goose blood shows a greatly elevated oxygen affinity compared to closely related species of geese. This is apparently due to a single proline to alanine mutation at the alpha 1 beta 1 interface which destabilises the T state of the protein. The beta chain N and C termini are well-localized, and together with other neighbouring basic groups they form a strongly positively charged groove at the entrance to the central cavity around the molecular dyad. The well-ordered conformation and the three-dimensional distribution of positive charges clearly indicate this area to be the inositol pentaphosphate binding site of bird haemoglobins.
The crystal structure of a high oxygen affinity species of haemoglobin (bar-headed goose haemoglobin in the oxy form).,Zhang J, Hua Z, Tame JR, Lu G, Zhang R, Gu X J Mol Biol. 1996 Jan 26;255(3):484-93. PMID:8568892
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑ Zhang J, Hua Z, Tame JR, Lu G, Zhang R, Gu X. The crystal structure of a high oxygen affinity species of haemoglobin (bar-headed goose haemoglobin in the oxy form). J Mol Biol. 1996 Jan 26;255(3):484-93. PMID:8568892 doi:http://dx.doi.org/10.1006/jmbi.1996.0040