1i22: Difference between revisions
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|PDB= 1i22 |SIZE=350|CAPTION= <scene name='initialview01'>1i22</scene>, resolution 1.80Å | |PDB= 1i22 |SIZE=350|CAPTION= <scene name='initialview01'>1i22</scene>, resolution 1.80Å | ||
|SITE= | |SITE= | ||
|LIGAND= <scene name='pdbligand=CA:CALCIUM ION'>CA</scene> | |LIGAND= <scene name='pdbligand=CA:CALCIUM+ION'>CA</scene> | ||
|ACTIVITY= [http://en.wikipedia.org/wiki/Lysozyme Lysozyme], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.17 3.2.1.17] | |ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Lysozyme Lysozyme], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.17 3.2.1.17] </span> | ||
|GENE= | |GENE= | ||
|DOMAIN= | |||
|RELATEDENTRY=[[1lz1|1LZ1]], [[1i1z|1I1Z]], [[1i20|1I20]], [[2lhm|2LHM]], [[3lhm|3LHM]] | |||
|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1i22 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1i22 OCA], [http://www.ebi.ac.uk/pdbsum/1i22 PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1i22 RCSB]</span> | |||
}} | }} | ||
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==Overview== | ==Overview== | ||
Structural determinants of Ca2+ binding sites within proteins typically comprise several acidic residues in appropriate juxtaposition. Three residues (Ala-83, Gln-86, and Ala-92) in human lysozyme are characteristically mutated to Lys, Asp, and Asp, respectively, in natural Ca2+ binding lysozymes and alpha-lactalbumins. The effects of these mutations on the stability and Ca2+ binding properties of human lysozyme were investigated using calorimetry and were interpreted with crystal structures. The double mutant, in which Glu-86 and Ala-92 were replaced with Asp, clearly showed Ca2+ binding affinity, whereas neither point mutant showed Ca2+ affinity, indicating that both residues are essential. The further mutation of Ala-83 --> Lys did not affect the Ca2+ binding of the double mutant. The point mutations Ala-83 --> Lys and Glu-86 --> Asp did not affect the stability, whereas the mutation Ala-92 --> Asp was about 1.3 kcal/mol less stable. Structural analyses showed that both Asp-86 and Lys-83 were exposed to solvent. Side chains of Asp-86 and Asp-91 were rotated in opposite directions about chi1 angle, as if to reduce the electrostatic repulsion. The charged amino acids at the Ca2+ binding site did not significantly affect stability of the protein, possibly because of the local conformational change of the side chains. | Structural determinants of Ca2+ binding sites within proteins typically comprise several acidic residues in appropriate juxtaposition. Three residues (Ala-83, Gln-86, and Ala-92) in human lysozyme are characteristically mutated to Lys, Asp, and Asp, respectively, in natural Ca2+ binding lysozymes and alpha-lactalbumins. The effects of these mutations on the stability and Ca2+ binding properties of human lysozyme were investigated using calorimetry and were interpreted with crystal structures. The double mutant, in which Glu-86 and Ala-92 were replaced with Asp, clearly showed Ca2+ binding affinity, whereas neither point mutant showed Ca2+ affinity, indicating that both residues are essential. The further mutation of Ala-83 --> Lys did not affect the Ca2+ binding of the double mutant. The point mutations Ala-83 --> Lys and Glu-86 --> Asp did not affect the stability, whereas the mutation Ala-92 --> Asp was about 1.3 kcal/mol less stable. Structural analyses showed that both Asp-86 and Lys-83 were exposed to solvent. Side chains of Asp-86 and Asp-91 were rotated in opposite directions about chi1 angle, as if to reduce the electrostatic repulsion. The charged amino acids at the Ca2+ binding site did not significantly affect stability of the protein, possibly because of the local conformational change of the side chains. | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Kuroki, R.]] | [[Category: Kuroki, R.]] | ||
[[Category: calcium binding site]] | [[Category: calcium binding site]] | ||
[[Category: hydrolase]] | [[Category: hydrolase]] | ||
[[Category: mutant human lysozyme]] | [[Category: mutant human lysozyme]] | ||
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