1sh4
Solution structure of oxidized bovine microsomal cytochrome B5 Mutant V45H
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OverviewOverview
A comparative study on the solution structures of bovine microsomal, cytochrome b5 (Tb5) and the mutant V45H has been achieved by 1D and 2D, 1H-NMR spectroscopy to clarify the differences in the solution, conformations between these two proteins. The results reveal that the, global folding of the V45H mutant in solution is unchanged, but the subtle, changes exist in the orientation of the axial ligand His39, and heme vinyl, groups. The side chain of His45 in V45H mutant extends to the outer edge, of the heme pocket leaving a cavity at the site originally occupied by the, inner methyl group of Val45 residue. In addition, the imidazole ring of, axial ligand His39 rotates counterclockwise by approximately 3 degrees, around the His-Fe-His axis, and the 4-heme vinyl group turns to the space, vacated by the removed side chain due to the mutation. Furthermore, the, helix III of the heme pocket undergoes outward displacement, while the, linkage between helix II and III is shifted leftward. These observations, are not only consistent with the pattern of the pseudocontact shifts of, the heme protons, but also well account for the lower stability of V45H, mutant against heat and urea.
About this StructureAbout this Structure
1SH4 is a Single protein structure of sequence from Bos taurus with HEM as ligand. Full crystallographic information is available from OCA.
ReferenceReference
The comparative study on the solution structures of the oxidized bovine microsomal cytochrome b5 and mutant V45H., Zhang Q, Cao C, Wang ZQ, Wang YH, Wu H, Huang ZX, Protein Sci. 2004 Aug;13(8):2161-9. PMID:15273310
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