1xrz
From Proteopedia
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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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==About this Structure== | ==About this Structure== | ||
| - | 1XRZ is a [[Single protein]] structure | + | 1XRZ is a [[Single protein]] structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XRZ OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Singh, R.]] | [[Category: Singh, R.]] | ||
[[Category: Weiss, M A.]] | [[Category: Weiss, M A.]] | ||
| - | [[Category: | + | [[Category: Cyclohexanylalanine]] |
| - | [[Category: | + | [[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 | + | |
Revision as of 12:26, 3 May 2008
NMR Structure of a Zinc Finger with Cyclohexanylalanine Substituted for the Central Aromatic Residue
Overview
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.
About this Structure
1XRZ is a Single protein structure. Full crystallographic 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 Sat May 3 15:26:13 2008
