This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
1xrz
From Proteopedia
| Line 1: | Line 1: | ||
[[Image:1xrz.jpg|left|200px]] | [[Image:1xrz.jpg|left|200px]] | ||
| - | + | <!-- | |
| - | + | The line below this paragraph, containing "STRUCTURE_1xrz", creates the "Structure Box" on the page. | |
| - | + | You may change the PDB parameter (which sets the PDB file loaded into the applet) | |
| - | + | or the SCENE parameter (which sets the initial scene displayed when the page is loaded), | |
| - | | | + | or leave the SCENE parameter empty for the default display. |
| - | | | + | --> |
| - | + | {{STRUCTURE_1xrz| PDB=1xrz | SCENE= }} | |
| - | + | ||
| - | + | ||
| - | }} | + | |
'''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''' | ||
| Line 19: | Line 16: | ||
==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== | ||
| Line 30: | Line 27: | ||
[[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
