1hv4

From Proteopedia

Revision as of 13:58, 15 February 2008

CRYSTAL STRUCTURE ANALYSIS OF BAR-HEAD GOOSE HEMOGLOBIN (DEOXY FORM)

Overview

The crystal structure of a high oxygen affinity species of hemoglobin, bar-headed goose hemoglobin in deoxy form, has been determined to a, resolution of 2.8 A. The R and R(free) factor of the model are 0.197 and, 0.243, respectively. The structure reported here is a special deoxy state, of hemoglobin and indicates the differences in allosteric mechanisms, between the goose and human hemoglobins. The quaternary structure of the, goose deoxy hemoglobin shows obvious differences from that of human deoxy, hemoglobin. The rotation angle of one alphabeta dimer relative to its, partner in a tetramer molecule from the goose oxy to deoxy hemoglobin is, only 4.6 degrees, and the translation is only 0.3 A, which are much, smaller than those in human hemoglobin. In the alpha(1)beta(2) switch, region of the goose deoxy hemoglobin, the imidazole ring of His beta(2)97, does not span the side-chain of Thr alpha(1)41 relative to the oxy, hemoglobin as in human hemoglobin. And the tertiary structure changes of, heme pocket and FG corner are also smaller than that in human hemoglobin., A unique mutation among avian and mammalian Hbs of alpha119 from proline, to alanine at the alpha(1)beta(1 )interface in bar-headed goose hemoglobin, brings a gap between Ala alpha119 and Leu beta55, the minimum distance, between the two residues is 4.66 A. At the entrance to the central cavity, around the molecular dyad, some residues of two beta chains form a, positively charged groove where the inositol pentaphosphate binds to the, hemoglobin. The His beta146 is at the inositol pentaphosphate binding site, and the salt-bridge between His beta146 and Asp beta94 does not exist in, the deoxy hemoglobin, which brings the weak chloride-independent Bohr, effect to bar-headed goose hemoglobin.

About this Structure

1HV4 is a Protein complex structure of sequences from Anser indicus with as ligand. Full crystallographic information is available from OCA.

Reference

The crystal structure of bar-headed goose hemoglobin in deoxy form: the allosteric mechanism of a hemoglobin species with high oxygen affinity., Liang Y, Hua Z, Liang X, Xu Q, Lu G, J Mol Biol. 2001 Oct 12;313(1):123-37. PMID:11601851

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