1A3V

STAPHYLOCOCCAL NUCLEASE, CYCLOPENTANE THIOL DISULFIDE TO V23C VARIANT

Summary for 1A3V

• Entry DOI: 10.2210/pdb1a3v/pdb
• Descriptor: STAPHYLOCOCCAL NUCLEASE, CALCIUM ION, THYMIDINE-3',5'-DIPHOSPHATE, ... (4 entities in total)
• Functional Keywords: nuclease, unnatural amino acid, hydrolase, endonuclease
• Biological source: Staphylococcus aureus
• Cellular location: Nuclease A: Secreted. Nuclease B: Membrane: P00644
• Total number of polymer chains: 1
• Total formula weight: 17389.79

Authors

Wynn, R.,Harkins, P.C.,Richards, F.M.,Fox, R.O. (deposition date: 1998-01-24, release date: 1998-04-29, Last modification date: 2023-08-02)

Primary citation

Wynn, R.,Harkins, P.C.,Richards, F.M.,Fox, R.O.
Comparison of straight chain and cyclic unnatural amino acids embedded in the core of staphylococcal nuclease.
Protein Sci., 6:1621-1626, 1997

PubMed Abstract: We have determined by X-ray crystallography the structures of several variants of staphylococcal nuclease with long flexible straight chain and equivalent length cyclic unnatural amino acid side chains embedded in the protein core. The terminal atoms in the straight side chains are not well defined by the observed electron density even though they remain buried within the protein interior. We have previously observed this behavior and have suggested that it may arise from the addition of side-chain vibrational and oscillational motions with each bond as a side chain grows away from the relatively rigid protein main chain and/or the population of multiple rotamers (Wynn R, Harkins P, Richards FM. Fox RO. 1996. Mobile unnatural amino acid side chains in the core of staphylococcal nuclease. Protein Sci 5:1026-1031). Reduction of the number of degrees of freedom by cyclization of a side chain would be expected to constrain these motions. These side chains are in fact well defined in the structures described here. Over-packing of the protein core results in a 1.0 A shift of helix 1 away from the site of mutation. Additionally, we have determined the structure of a side chain containing a single hydrogen to fluorine atom replacement on a methyl group. A fluorine atom is intermediate in size between methyl group and a hydrogen atom. The fluorine atom is observed in a single position indicating it does not rotate like methyl hydrogen atoms. This change also causes subtle differences in the packing interactions.

PubMed: 9260275

Experimental method

X-RAY DIFFRACTION (2.2 Å)