1moc

HIGH-RESOLUTION CRYSTAL STRUCTURES OF DISTAL HISTIDINE MUTANTS OF SPERM WHALE MYOGLOBIN

spinqualitylabelsall models 1moc, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1moc is a 1 chain structure with sequence from Physeter catodon. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CMO, HEM, SO4 Resources: FirstGlance, OCA, RCSB, PDBsum Function [MYG_PHYMC] 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 highly conserved distal histidine residue (His64) of sperm whale myoglobin modulates the affinity of ligands. In an effort to fully characterize the effects of mutating residue 64, we have determined the high-resolution crystal structures of the Gly64, Val64, Leu64, Thr64 and Gln64 mutants in several liganded forms. Metmyoglobins with hydrophobic substitutions at residue 64 (Val64 and Leu64) lack a water molecule at the sixth coordination position, while those with polar amino acid residues at this position (wild-type and Gln64) retain a covalently bound water molecule. In the Thr64 mutant, the bound water position is only partially occupied. In contrast, mutating the distal histidine residue to glycine does not cause loss of the coordinated water molecule, because the hydrogen bond from the imidazole side-chain is replaced by one from a well-ordered solvent water molecule. Differences in water structure around the distal pocket are apparent also in the structures of deoxymyoglobin mutants. The water molecule that is hydrogen-bonded to the N epsilon atom of histidine 64 in wild-type deoxymyoglobin is not found in any of the position 64 mutant structures that were determined. Comparison of the carbonmonoxy structures of wild-type, Gly64, Leu64 and Gln64 myoglobins in the P6 crystal form shows that the conformation of the Fe-C-O complex is nearly linear and is independent of the identity of the amino acid residue at position 64. However, the effect of CO binding on the conformation of residue 64 is striking. Superposition of deoxy and carbonmonoxy structures reveals significant displacements of the residue 64 side-chain in the wild-type and Gln64 myoglobins, but no displacement in the Leu64 mutant. These detailed structural studies provide key insights into the mechanisms of ligand binding and discrimination in myoglobin. High-resolution crystal structures of distal histidine mutants of sperm whale myoglobin.,Quillin ML, Arduini RM, Olson JS, Phillips GN Jr J Mol Biol. 1993 Nov 5;234(1):140-55. PMID:8230194 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Myoglobin

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