3NUC: STAPHLOCOCCAL NUCLEASE, 1-N-PROPANE THIOL DISULFIDE TO V23C VARIANT

Citation:
Abstract
The structures of several variants of staphylococcal nuclease with long flexible unnatural amino acid side chains in the hydrophobic core have been determined by X-ray crystallography. The unnatural amino acids are disulfide moieties between the lone cysteine residue in V23C nuclease and methane, ethane, 1-n-propane, 1-n-butane, 1-n-pentane, and 2-hydroxyethyl thiols. We have examined changes in the core packing of these mutants. Side chains as large as the 1-n-propyl cysteine disulfide can be incorporated without perturbation of the structure. This is due, in part, to cavities present in the wild-type protein. The longest side chains are not well defined, even though they remain buried within the protein interior. These results suggest that the enthalpy-entropy balance that governs the rigidity of protein interiors favors tight packing only weakly. Additionally, the tight packing observed normally in protein interiors may reflect, in part, the limited numbers of rotamers available to the natural amino acids.
PDB ID: 3NUCDownload
MMDB ID: 54589
PDB Deposition Date: 1997/12/6
Updated in MMDB: 2012/11
Experimental Method:
x-ray diffraction
Resolution: 1.9  Å
Source Organism:
Similar Structures:
Biological Unit for 3NUC: monomeric; determined by author
Molecular Components in 3NUC
Label Count Molecule
Protein (1 molecule)
1
Staphylococcal Nuclease
Molecule annotation
Chemicals (2 molecules)
1
1
2
1
* Click molecule labels to explore molecular sequence information.

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