Primary Citation of Related Structures: 1AZI, 1BJE
PubMed Abstract:
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 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.
Related Citations:
A Myoglobin Variant with a Polar Substitution in a Conserved Hydrophobic Cluster in the Heme Binding Pocket Maurus, R., Overall, C.M., Bogumil, R., Luo, Y., Mauk, A.G., Smith, M., Brayer, G.D. (1997) Biochim Biophys Acta 1341: 1
Structural Characterization of Heme Ligation in the His64-->Tyr Variant of Myoglobin Maurus, R., Bogumil, R., Luo, Y., Tang, H.L., Smith, M., Mauk, A.G., Brayer, G.D. (1994) J Biol Chem 269: 12606
Ftir Analysis of the Interaction of Azide with Horse Heart Myoglobin Variants Bogumil, R., Hunter, C.L., Maurus, R., Tang, H.L., Lee, H., Lloyd, E., Brayer, G.D., Smith, M., Mauk, A.G. (1994) Biochemistry 33: 7600
Three-Dimensional Structure of Cyanomet-Sulfmyoglobin C Evans, S.V., Sishta, B.P., Mauk, A.G., Brayer, G.D. (1994) Proc Natl Acad Sci U S A 91: 4723
Expression in Escherichia Coli of a Synthetic Gene Coding for Horse Heart Myoglobin Guillemette, J.G., Matsushima-Hibiya, Y., Atkinson, T., Smith, M. (1991) Protein Eng 4: 585
High-Resolution Study of the Three-Dimensional Structure of Horse Heart Metmyoglobin Evans, S.V., Brayer, G.D. (1990) J Mol Biol 213: 885
Crystallization and Preliminary Diffraction Data for Horse Heart Metmyoglobin Sherwood, C., Mauk, A.G., Brayer, G.D. (1987) J Mol Biol 193: 227
Organizational Affiliation:
Department of Biochemistry and Molecular Biology and the Protein Engineering Network of Centres of Excellence, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada.
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