1xrz
From Proteopedia
(New page: 200px<br /> <applet load="1xrz" size="450" color="white" frame="true" align="right" spinBox="true" caption="1xrz" /> '''NMR Structure of a Zinc Finger with Cyclohe...) |
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'''NMR Structure of a Zinc Finger with Cyclohexanylalanine Substituted for the Central Aromatic Residue'''<br /> | '''NMR Structure of a Zinc Finger with Cyclohexanylalanine Substituted for the Central Aromatic Residue'''<br /> | ||
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==About this Structure== | ==About this Structure== | ||
| - | 1XRZ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/ ] with ZN as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 1XRZ is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/ ] with <scene name='pdbligand=ZN:'>ZN</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XRZ OCA]. |
==Reference== | ==Reference== | ||
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[[Category: zinc finger]] | [[Category: zinc finger]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri Feb 15 17:10:20 2008'' |
Revision as of 15:10, 15 February 2008
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NMR Structure of a Zinc Finger with Cyclohexanylalanine Substituted for the Central Aromatic Residue
Contents |
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.
Disease
Known disease associated with this structure: Spastic paraplegia 33 OMIM:[610243]
About this Structure
1XRZ is a Single protein structure of sequence from [1] with as ligand. 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
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