3bdc | pdb_00003bdc

Crystal structure of Staphylococcal nuclease variant Delta+PHS at cryogenic temperature

spinqualitylabelsall models 3bdc, resolution 1.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3bdc 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 Related: 2rbm, 3c1e, 3c1f, 3d4d, 3d6c, 3dmu, 3e5s, 3eji, 3ero, 3erq, 3evq Activity: Micrococcal nuclease, with EC number 3.1.31.1 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [NUC_STAAW] Enzyme that catalyzes the hydrolysis of both DNA and RNA at the 5' position of the phosphodiester bond (By similarity). 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 Prior computational studies of the acid-unfolding behavior of staphylococcal nuclease (SNase) suggest that the pK(a) values of its carboxylic groups are difficult to reproduce with electrostatics calculations with continuum methods. To examine the molecular determinants of the pK(a) values of carboxylic groups in SNase, the pK(a) values of all 20 Asp and Glu residues were measured with multidimensional and multinuclear NMR spectroscopy in an acid insensitive variant of SNase. The crystal structure of the protein was obtained to describe the microenvironments of the carboxylic groups. Fourteen Asp and Glu residues titrate with relatively normal pK(a) values that are depressed by less than 1.1 units relative to the normal pK(a) of Asp and Glu in water. Only six residues have pK(a) values shifted by more than 1.5 units. Asp-21 has an unusually high pK(a) of 6.5, which is probably the result of interactions with other carboxylic groups at the active site. The most perturbed pK(a) values appear to be governed by hydrogen bonding and not by Coulomb interactions. The pK(a) values calculated with standard continuum electrostatics methods applied to static structures are more depressed than the measured values because Coulomb effects are exaggerated in the calculations. The problems persist even when the protein is treated with the dielectric constant of water. This can be interpreted to imply that structural relaxation is an important determinant of the pK(a) values; however, no major pH-sensitive conformational reorganization of the backbone was detected using NMR spectroscopy. Proteins 2009. (c) 2009 Wiley-Liss, Inc. Molecular determinants of the pK(a) values of Asp and Glu residues in staphylococcal nuclease.,Castaneda CA, Fitch CA, Majumdar A, Khangulov V, Schlessman JL, Garcia-Moreno BE Proteins. 2009 May 4;77(3):570-588. PMID:19533744 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Staphylococcal nuclease 3D structures

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