2rks

<table><tr><td colspan='2'>[[2rks]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/"micrococcus_aureus"_(rosenbach_1884)_zopf_1885 "micrococcus aureus" (rosenbach 1884) zopf 1885]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2RKS OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2RKS FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</scene></td></tr>

<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat"><div style='overflow: auto; max-height: 3em;'>[[2rbm|2rbm]]</div></td></tr>

<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">nuc ([https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=1280 "Micrococcus aureus" (Rosenbach 1884) Zopf 1885])</td></tr>

<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[https://en.wikipedia.org/wiki/Micrococcal_nuclease Micrococcal nuclease], with EC number [https://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.31.1 3.1.31.1] </span></td></tr>

[[https://www.uniprot.org/uniprot/NUC_STAAW NUC_STAAW]] Enzyme that catalyzes the hydrolysis of both DNA and RNA at the 5' position of the phosphodiester bond (By similarity).

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== Publication Abstract from PubMed ==

Previously we reported that Lys, Asp, and Glu residues at positions 66 and 92 in staphylococcal nuclease (SNase) titrate with pK(a) values shifted by up to 5 pK(a) units in the direction that promotes the neutral state. In contrast, the internal Lys-38 in SNase titrates with a normal pK(a). The crystal structure of the L38K variant shows that the side chain of Lys-38 is buried. The ionizable moiety is approximately 7 A from solvent and ion paired with Glu-122. This suggests that the pK(a) value of Lys-38 is normal because the energetic penalty for dehydration is offset by a favorable Coulomb interaction. However, the pK(a) of Lys-38 was also normal when Glu-122 was replaced with Gln or with Ala. Continuum electrostatics calculations were unable to reproduce the pK(a) of Lys-38 unless the protein was treated with an artificially high dielectric constant, consistent with structural reorganization being responsible for the normal pK(a) value of Lys-38. This reorganization must be local because circular dichroism and NMR spectroscopy indicate that the L38K protein is native-like under all conditions studied. In molecular dynamics simulations, the ion pair between Lys-38 and Glu-122 is unstable. The simulations show that a minor rearrangement of a loop is sufficient to allow penetration of water to the amino moiety of Lys-38. This illustrates both the important roles of local flexibility and water penetration as determinants of pK(a) values of ionizable groups buried near the protein-water interface, and the challenges faced by structure-based pK(a) calculations in reproducing these effects.

A buried lysine that titrates with a normal pKa: role of conformational flexibility at the protein-water interface as a determinant of pKa values.,Harms MJ, Schlessman JL, Chimenti MS, Sue GR, Damjanovic A, Garcia-Moreno B Protein Sci. 2008 May;17(5):833-45. Epub 2008 Mar 27. PMID:18369193<ref>PMID:18369193</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 2rks" style="background-color:#fffaf0;"></div>

== References ==

<references/>

[[Category: Micrococcal nuclease]]

[[Category: Garcia-Moreno, E B]]

[[Category: Harms, M J]]

[[Category: Schlessman, J L]]

[[Category: Staphylococcal nuclease]]