1k22: Difference between revisions
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|PDB= 1k22 |SIZE=350|CAPTION= <scene name='initialview01'>1k22</scene>, resolution 1.93Å | |PDB= 1k22 |SIZE=350|CAPTION= <scene name='initialview01'>1k22</scene>, resolution 1.93Å | ||
|SITE= | |SITE= | ||
|LIGAND= | |LIGAND= <scene name='pdbligand=MEL:[((1R)-2-{(2S)-2-[({4-[AMINO(IMINO)METHYL]BENZYL}AMINO)CARBONYL]AZETIDINYL}-1-CYCLOHEXYL-2-OXOETHYL)AMINO]ACETIC+ACID'>MEL</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=TYS:SULFONATED+TYROSINE'>TYS</scene> | ||
|ACTIVITY= [http://en.wikipedia.org/wiki/Thrombin Thrombin], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.5 3.4.21.5] | |ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Thrombin Thrombin], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.21.5 3.4.21.5] </span> | ||
|GENE= | |GENE= | ||
|DOMAIN= | |||
|RELATEDENTRY=[[1k1i|1K1I]], [[1k1j|1K1J]], [[1k1m|1K1M]], [[1k1l|1K1L]], [[1k1n|1K1N]], [[1k1o|1K1O]], [[1k1p|1K1P]], [[1k21|1K21]] | |||
|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1k22 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1k22 OCA], [http://www.ebi.ac.uk/pdbsum/1k22 PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1k22 RCSB]</span> | |||
}} | }} | ||
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==Overview== | ==Overview== | ||
The binding of a series of low molecular weight ligands towards trypsin and thrombin has been studied by isothermal titration calorimetry and protein crystallography. In a series of congeneric ligands, surprising changes of protonation states occur and are overlaid on the binding process. They result from induced pK(a) shifts depending on the local environment experienced by the ligand and protein functional groups in the complex (induced dielectric fit). They involve additional heat effects that must be corrected before any conclusion on the binding enthalpy (DeltaH) and entropy (DeltaS) can be drawn. After correction, trends in both contributions can be interpreted in structural terms with respect to the hydrogen bond inventory or residual ligand motions. For all inhibitors studied, a strong negative heat capacity change (DeltaC(p)) is detected, thus binding becomes more exothermic and entropically less favourable with increasing temperature. Due to a mutual compensation, Gibbs free energy remains virtually unchanged. The strong negative DeltaC(p) value cannot solely be explained by the removal of hydrophobic surface portions of the protein or ligand from water exposure. Additional contributions must be considered, presumably arising from modulations of the local water structure, changes in vibrational modes or other ordering parameters. For thrombin, smaller negative DeltaC(p) values are observed for ligand binding in the presence of sodium ions compared to the other alkali ions, probably due to stabilising effects on the protein or changes in the bound water structure. | The binding of a series of low molecular weight ligands towards trypsin and thrombin has been studied by isothermal titration calorimetry and protein crystallography. In a series of congeneric ligands, surprising changes of protonation states occur and are overlaid on the binding process. They result from induced pK(a) shifts depending on the local environment experienced by the ligand and protein functional groups in the complex (induced dielectric fit). They involve additional heat effects that must be corrected before any conclusion on the binding enthalpy (DeltaH) and entropy (DeltaS) can be drawn. After correction, trends in both contributions can be interpreted in structural terms with respect to the hydrogen bond inventory or residual ligand motions. For all inhibitors studied, a strong negative heat capacity change (DeltaC(p)) is detected, thus binding becomes more exothermic and entropically less favourable with increasing temperature. Due to a mutual compensation, Gibbs free energy remains virtually unchanged. The strong negative DeltaC(p) value cannot solely be explained by the removal of hydrophobic surface portions of the protein or ligand from water exposure. Additional contributions must be considered, presumably arising from modulations of the local water structure, changes in vibrational modes or other ordering parameters. For thrombin, smaller negative DeltaC(p) values are observed for ligand binding in the presence of sodium ions compared to the other alkali ions, probably due to stabilising effects on the protein or changes in the bound water structure. | ||
==About this Structure== | ==About this Structure== | ||
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[[Category: Musil, D.]] | [[Category: Musil, D.]] | ||
[[Category: Stubbs, M T.]] | [[Category: Stubbs, M T.]] | ||
[[Category: complex (serine protease/inhibitor)]] | [[Category: complex (serine protease/inhibitor)]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 21:42:18 2008'' | ||
Revision as of 21:42, 30 March 2008
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| , resolution 1.93Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | , , , | ||||||
| Activity: | Thrombin, with EC number 3.4.21.5 | ||||||
| Related: | 1K1I, 1K1J, 1K1M, 1K1L, 1K1N, 1K1O, 1K1P, 1K21
| ||||||
| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
HUMAN THROMBIN-INHIBITOR COMPLEX
OverviewOverview
The binding of a series of low molecular weight ligands towards trypsin and thrombin has been studied by isothermal titration calorimetry and protein crystallography. In a series of congeneric ligands, surprising changes of protonation states occur and are overlaid on the binding process. They result from induced pK(a) shifts depending on the local environment experienced by the ligand and protein functional groups in the complex (induced dielectric fit). They involve additional heat effects that must be corrected before any conclusion on the binding enthalpy (DeltaH) and entropy (DeltaS) can be drawn. After correction, trends in both contributions can be interpreted in structural terms with respect to the hydrogen bond inventory or residual ligand motions. For all inhibitors studied, a strong negative heat capacity change (DeltaC(p)) is detected, thus binding becomes more exothermic and entropically less favourable with increasing temperature. Due to a mutual compensation, Gibbs free energy remains virtually unchanged. The strong negative DeltaC(p) value cannot solely be explained by the removal of hydrophobic surface portions of the protein or ligand from water exposure. Additional contributions must be considered, presumably arising from modulations of the local water structure, changes in vibrational modes or other ordering parameters. For thrombin, smaller negative DeltaC(p) values are observed for ligand binding in the presence of sodium ions compared to the other alkali ions, probably due to stabilising effects on the protein or changes in the bound water structure.
About this StructureAbout this Structure
1K22 is a Protein complex structure of sequences from Hirudo medicinalis and Homo sapiens. Full crystallographic information is available from OCA.
ReferenceReference
Factorising ligand affinity: a combined thermodynamic and crystallographic study of trypsin and thrombin inhibition., Dullweber F, Stubbs MT, Musil D, Sturzebecher J, Klebe G, J Mol Biol. 2001 Oct 26;313(3):593-614. PMID:11676542
Page seeded by OCA on Sun Mar 30 21:42:18 2008