1hsy

ORIGIN OF THE PH-DEPENDENT SPECTROSCOPIC PROPERTIES OF PENTACOORDINATE METMYOGLOBIN VARIANTS

spinqualitylabelsall models 1hsy, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1hsy is a 1 chain structure with sequence from Equus caballus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.9Å Ligands: HEM, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function MYG_HORSE Serves as a reserve supply of oxygen and facilitates the movement of oxygen within muscles. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The pH dependence of the electronic and EPR spectra of two variants of horse heart myoglobin (Mb) in which the distal His64 ligand has been replaced by either Thr or Ile has been studied. Both of these variants exhibit spectroscopic changes with pH that are indicative of a transition between two ferric high-spin forms that occurs with a pKa of 9.49 for the His64Thr variant and 9.26 for the His64Ile variant and that is distinctly different from the pH-dependent spectroscopic changes related to titration of the distal aquo ligand of wild-type Mb. The electronic and EPR spectra of both variants at all values of pH studied are consistent with the presence of a pentacoordinate heme iron center. For the His64Thr variant, a high-resolution (1.9 A) structure determination establishes the lack of the distal aquo ligand and demonstrates an out-of-plane movement of the ferric iron toward the proximal histidine together with a decrease of the Fe-His bond length. Investigation of this pH-linked equilibrium by EPR spectroscopy reveals rhombically split high-spin signals at both pH 7 and 11 with a greater degree of rhombicity exhibited by the alkaline species. We propose that the pH-linked spectroscopic transition exhibited by these distal histidine variants results from the deprotonation of the proximal His93 residue to produce imidazolate ligation at alkaline pH. Origin of the pH-dependent spectroscopic properties of pentacoordinate metmyoglobin variants.,Bogumil R, Maurus R, Hildebrand DP, Brayer GD, Mauk AG Biochemistry. 1995 Aug 22;34(33):10483-90. PMID:7654702 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Myoglobin 3D structures

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