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| | {{STRUCTURE_1xrz| PDB=1xrz | SCENE= }} | | {{STRUCTURE_1xrz| PDB=1xrz | SCENE= }} |
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| - | '''NMR Structure of a Zinc Finger with Cyclohexanylalanine Substituted for the Central Aromatic Residue'''
| + | ===NMR Structure of a Zinc Finger with Cyclohexanylalanine Substituted for the Central Aromatic Residue=== |
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| - | ==Overview==
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| - | The classical Zn finger contains a phenylalanine at the crux of its three architectural elements: a beta-hairpin, an alpha-helix, and a Zn(2+)-binding site. Surprisingly, phenylalanine is not required for high-affinity Zn2+ binding, but instead contributes to the specification of a precise DNA-binding surface. Substitution of phenylalanine by leucine leads to a floppy but native-like structure whose Zn affinity is maintained by marked entropy-enthalpy compensation (DeltaDeltaH -8.3 kcal/mol and -TDeltaDeltaS 7.7 kcal/mol). Phenylalanine and leucine differ in shape, size, and aromaticity. To distinguish which features correlate with dynamic stability, we have investigated a nonstandard finger containing cyclohexanylalanine at this site. The structure of the nonstandard finger is similar to that of the native domain. The cyclohexanyl ring assumes a chair conformation, and conformational fluctuations characteristic of the leucine variant are damped. Although the nonstandard finger exhibits a lower affinity for Zn2+ than does the native domain (DeltaDeltaG -1.2 kcal/mol), leucine-associated perturbations in enthalpy and entropy are almost completely attenuated (DeltaDeltaH -0.7 kcal/mol and -TDeltaDeltaS -0.5 kcal/mol). Strikingly, global changes in entropy (as inferred from calorimetry) are in each case opposite in sign from changes in configurational entropy (as inferred from NMR). This seeming paradox suggests that enthalpy-entropy compensation is dominated by solvent reorganization rather than nominal molecular properties. Together, these results demonstrate that dynamic and thermodynamic perturbations correlate with formation or repair of a solvated packing defect rather than type of physical interaction (aromatic or aliphatic) within the core. | + | The line below this paragraph, {{ABSTRACT_PUBMED_15557258}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 15557258 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_15557258}} |
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| | ==About this Structure== | | ==About this Structure== |
| - | 1XRZ is a [[Single protein]] structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XRZ OCA]. | + | 1XRZ is a [[Single protein]] structure. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XRZ OCA]. |
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| | ==Reference== | | ==Reference== |
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| | [[Category: Cyclohexanylalanine]] | | [[Category: Cyclohexanylalanine]] |
| | [[Category: Zinc finger]] | | [[Category: Zinc finger]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 15:26:13 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 12:49:14 2008'' |
Revision as of 09:49, 27 July 2008
Template:STRUCTURE 1xrz
NMR Structure of a Zinc Finger with Cyclohexanylalanine Substituted for the Central Aromatic Residue
Template:ABSTRACT PUBMED 15557258
About this Structure
1XRZ is a Single protein structure. Full experimental information is available from OCA.
Reference
Solvation and the hidden thermodynamics of a zinc finger probed by nonstandard repair of a protein crevice., Lachenmann MJ, Ladbury JE, Qian X, Huang K, Singh R, Weiss MA, Protein Sci. 2004 Dec;13(12):3115-26. PMID:15557258
Page seeded by OCA on Sun Jul 27 12:49:14 2008
