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1xrz

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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'''
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===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.
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(as it appears on PubMed at http://www.pubmed.gov), where 15557258 is the PubMed ID number.
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{{ABSTRACT_PUBMED_15557258}}
==About this Structure==
==About this Structure==
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1XRZ is a [[Single protein]] structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XRZ OCA].
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1XRZ is a [[Single protein]] structure. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XRZ OCA].
==Reference==
==Reference==
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[[Category: Cyclohexanylalanine]]
[[Category: Cyclohexanylalanine]]
[[Category: Zinc finger]]
[[Category: Zinc finger]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 15:26:13 2008''
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''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

Image:1xrz.png

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

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