The crystal structure of a high oxygen affinity species of haemoglobin (bar-headed goose haemoglobin in the oxy form).
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.
Zhang
J
J
College of Life Sciences Peking University, Beijing, China.
Hua
Z
Z
Tame
J R
JR
Lu
G
G
Zhang
R
R
Gu
X
X
D019794:2,3-Diphosphoglycerate; D000818:Animals; D003460:Crystallization; D018360:Crystallography, X-Ray; D004163:Diphosphoglyceric Acids / Q000378:metabolism; D005777:Geese; D006418:Heme / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism; D009154:Mutation; D010100:Oxygen / Q000378:metabolism; D010108:Oxyhemoglobins / Q000737:chemistry*; D011487:Protein Conformation
D004163:Diphosphoglyceric Acids; D006454:Hemoglobins; D007295:Inositol Phosphates; D010108:Oxyhemoglobins; D019794:2,3-Diphosphoglycerate; C013571:inositol pentaphosphate; D006418:Heme; D010100:Oxygen