1snd
STAPHYLOCOCCAL NUCLEASE DIMER CONTAINING A DELETION OF RESIDUES 114-119 COMPLEXED WITH CALCIUM CHLORIDE AND THE COMPETITIVE INHIBITOR DEOXYTHYMIDINE-3',5'-DIPHOSPHATE
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OverviewOverview
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.
About this StructureAbout this Structure
1SND is a Single protein structure of sequence from Staphylococcus aureus. Active as Micrococcal nuclease, with EC number 3.1.31.1 Full crystallographic information is available from OCA.
ReferenceReference
One-step evolution of a dimer from a monomeric protein., Green SM, Gittis AG, Meeker AK, Lattman EE, Nat Struct Biol. 1995 Sep;2(9):746-51. PMID:7552745
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