1SND: Staphylococcal Nuclease Dimer Containing A Deletion Of Residues 114- 119 Complexed With Calcium Chloride And The Competitive Inhibitor Deoxythymidine-3',5'-Diphosphate

Deletion of six amino acids in a surface loop transforms staphylococcal nuclease from a monomeric protein into a very stable dimer (Kd < 1 x 10(-8)M). A 2 A X-ray crystal structure of the dimer (R = 0.176) shows that the carboxy-terminal alpha-helix has been stripped from its normal position in one monomer and is now incorporated into the equivalent position on the adjoining monomer. This swapping creates an association interface of 2900 A 2. A second, smaller interface of 460 A 2 is also formed. The spontaneous exchange or swapping of secondary structural elements provides a simple pathway for the formation of large, stable protein/protein interfaces and may play an important role in the evolution of oligomeric proteins.
PDB ID: 1SNDDownload
MMDB ID: 5780
PDB Deposition Date: 1996/8/23
Updated in MMDB: 2011/11
Experimental Method:
x-ray diffraction
Resolution: 1.84  Å
Source Organism:
Similar Structures:
Biological Unit for 1SND: tetrameric; determined by author and by software (PQS)
Molecular Components in 1SND
Label Count Molecule
Proteins (4 molecules)
Staphylococcal Nuclease Dimer
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB