3dhq | pdb_00003dhq

Crystal structure of Staphylococcal nuclease variant Delta+PHS A90R at cryogenic temperature

spinqualitylabelsall models 3dhq, resolution 2.15Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3dhq is a 1 chain structure with sequence from "micrococcus_aureus"_(rosenbach_1884)_zopf_1885 "micrococcus aureus" (rosenbach 1884) zopf 1885. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CA, THP Related: 3d8g, 3d4w Gene: nuc ("Micrococcus aureus" (Rosenbach 1884) Zopf 1885) Activity: Micrococcal nuclease, with EC number 3.1.31.1 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT 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 Many functionally essential ionizable groups are buried in the hydrophobic interior of proteins. A systematic study of Lys, Asp, and Glu residues at 25 internal positions in staphylococcal nuclease showed that their pK(a) values can be highly anomalous, some shifted by as many as 5.7 pH units relative to normal pK(a) values in water. Here we show that, in contrast, Arg residues at the same internal positions exhibit no detectable shifts in pK(a); they are all charged at pH </= 10. Twenty-three of these 25 variants with Arg are folded at both pH 7 and 10. The mean decrease in thermodynamic stability from substitution with Arg was 6.2 kcal/mol at this pH, comparable to that for substitution with Lys, Asp, or Glu at pH 7. The physical basis behind the remarkable ability of Arg residues to remain protonated in environments otherwise incompatible with charges is suggested by crystal structures of three variants showing how the guanidinium moiety of the Arg side chain is effectively neutralized through multiple hydrogen bonds to protein polar atoms and to site-bound water molecules. The length of the Arg side chain, and slight deformations of the protein, facilitate placement of the guanidinium moieties near polar groups or bulk water. This unique capacity of Arg side chains to retain their charge in dehydrated environments likely contributes toward the important functional roles of internal Arg residues in situations where a charge is needed in the interior of a protein, in a lipid bilayer, or in similarly hydrophobic environments. Arginine residues at internal positions in a protein are always charged.,Harms MJ, Schlessman JL, Sue GR, Garcia-Moreno E B Proc Natl Acad Sci U S A. 2011 Nov 22;108(47):18954-9. Epub 2011 Nov 11. PMID:22080604 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Staphylococcal nuclease

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