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Acta Crystallogr D Biol Crystallogr. 2011 May;67(Pt 5):395-402. doi: 10.1107/S0907444911006044. Epub 2011 Apr 13.

Structure of Greyhound hemoglobin: origin of high oxygen affinity.

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1
Biophysics Graduate Program, The Ohio State University, Columbus, OH 43210, USA.

Abstract

This study presents the crystal structure of Greyhound hemoglobin (GrHb) determined to 1.9 Å resolution. GrHb was found to crystallize with an α₁β₁ dimer in the asymmetric unit and belongs to the R2 state. Oxygen-affinity measurements combined with the fact that GrHb crystallizes in the R2 state despite the high-salt conditions used for crystallization strongly indicate that GrHb can serve as a model high-oxygen-affinity hemoglobin (Hb) for higher mammals, especially humans. Structural analysis of GrHb and its comparison with the R2-state of human Hb revealed several regions that can potentially contribute to the high oxygen affinity of GrHb and serve to rationalize the additional stability of the R2-state of GrHb. A previously well studied hydrophobic cluster of bar-headed goose Hb near α119 was also incorporated in the comparison between GrHb and human Hb. Finally, a structural comparison with generic dog Hb and maned wolf Hb was conducted, revealing that in contrast to GrHb these structures belong to the R state of Hb and raising the intriguing possibility of an additional allosteric factor co-purifying with GrHb that can modulate its quaternary structure.

PMID:
21543841
DOI:
10.1107/S0907444911006044
[Indexed for MEDLINE]

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