1bje

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spinqualitylabelsall models 1bje, resolution 1.8Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

H64T VARIANT OF MYOGLOBIN (HORSE HEART) RECOMBINANT WILD-TYPE COMPLEXED WITH AZIDE

Overview

The high-resolution X-ray crystallographic structures of horse heart, azidometmyoglobin complexes of the wild-type protein and the His-64-->Thr, variant have been determined to 2.0 and 1.8 A respectively. Azide binds to, wild-type metmyoglobin in a bent configuration with an Fe-N-1-N-3 angle of, 119 degrees and is oriented into the distal crevice in the direction of, Ile-107. The proximity of the His-64 NE2 atom to the N-1 atom of the bound, azide indicates stabilization of the ligand by the His-64 side chain, through hydrogen bonding. In addition, structural characterization of, wild-type horse heart azidometmyoglobin establishes that the only, structural change induced by ligand binding is a small movement of the, Leu-29 side chain away from the azide ligand. EPR and Fourier transform, infrared spectroscopy were used to characterize the myoglobin azide, complexes further. EPR spectroscopy revealed that, in contrast with, wild-type azidometmyoglobin, two slightly different low-spin species are, formed by azide bound to the His-64-->Thr variant both in solution and in, a polycrystalline sample. One of these low-spin species has a greater, relative intensity, with g values very similar to those of the azide, complex of the wild-type protein. These EPR results together with, structural information on this variant indicate the presence of two, distinct conformations of bound azide, with one form predominating. The, major conformation is comparable to that formed by wild-type myoglobin in, which azide is oriented into the distal crevice. In the minor conformation, the azide is oriented towards the exterior of the protein.

About this Structure

1BJE is a Single protein structure of sequence from Equus caballus with SO4, AZI and HEM as ligands. Full crystallographic information is available from OCA.

Reference

Structural and spectroscopic studies of azide complexes of horse heart myoglobin and the His-64-->Thr variant., Maurus R, Bogumil R, Nguyen NT, Mauk AG, Brayer G, Biochem J. 1998 May 15;332 ( Pt 1):67-74. PMID:9576852

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