1a2t
STAPHYLOCOCCAL NUCLEASE, B-MERCAPTOETHANOL DISULFIDE TO V23C VARIANT
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| , resolution 1.96Å | |||||||
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| Ligands: | and | ||||||
| Activity: | Micrococcal nuclease, with EC number 3.1.31.1 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
OverviewOverview
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.
About this StructureAbout this Structure
1A2T is a Single protein structure of sequence from Staphylococcus aureus. Full crystallographic information is available from OCA.
ReferenceReference
Mobile unnatural amino acid side chains in the core of staphylococcal nuclease., Wynn R, Harkins PC, Richards FM, Fox RO, Protein Sci. 1996 Jun;5(6):1026-31. PMID:8762134
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