1enc

CRYSTAL STRUCTURES OF THE BINARY CA2+ AND PDTP COMPLEXES AND THE TERNARY COMPLEX OF THE ASP 21->GLU MUTANT OF STAPHYLOCOCCAL NUCLEASE. IMPLICATIONS FOR CATALYSIS AND LIGAND BINDING

spinqualitylabelsall models 1enc, resolution 1.95Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1enc is a 1 chain structure with sequence from Staphylococcus aureus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CA, THP Activity: Micrococcal nuclease, with EC number 3.1.31.1 Resources: FirstGlance, OCA, RCSB, PDBsum Function [NUC_STAAU] Enzyme that catalyzes the hydrolysis of both DNA and RNA at the 5' position of the phosphodiester bond. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The crystal structure of the Asp21-->Glu mutant (D21E) of staphylococcal nuclease (SNase) has been determined in three different complex forms. The structure of the D21E ternary complex in which D21E is bound to both Ca2+ and the transition-state analogue, thymidine 3',5'-diphosphate (pdTp), was determined to 1.95-A resolution. The structures of both binary complexes, D21E bound either to Ca2+ or pdTp, were determined to 2.15- and 2.05-A resolution, respectively. In the ternary structure, we find a 1.5-A movement of the Ca2+ in the active site, evidence of bidentate coordination of Ca2+ by Glu21 and inner-sphere coordination of the Ca2+ by Glu43. Comparison of the D21E binary structures with the ternary model shows large movements of active site side chains expected to play a direct role in catalysis. Glu43 moves in the binary nucleotide complex, whereas Arg35 is oriented differently in the binary metal complex. From these changes, we seek to explain the basis for the 1500-fold decrease in Vmax of D21E relative to wild-type SNase (WT). Furthermore, we describe direct structural evidence which explains the cooperativity of Ca2+ and pdTp binding in the ternary complex relative to that of the binary complexes. Crystal structures of the binary Ca2+ and pdTp complexes and the ternary complex of the Asp21-->Glu mutant of staphylococcal nuclease. Implications for catalysis and ligand binding.,Libson AM, Gittis AG, Lattman EE Biochemistry. 1994 Jul 5;33(26):8007-16. PMID:8025105 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Staphylococcal nuclease

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