View source for 231d


==STRUCTURE OF A DNA-PORPHYRIN COMPLEX==
<StructureSection load='231d' size='340' side='right'caption='[[231d]], [[Resolution|resolution]] 2.40&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[231d]] is a 1 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=231D OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=231D FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.4&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=PCU:CU(II)MESO(4-N-TETRAMETHYLPYRIDYL)PORPHYRIN'>PCU</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=231d FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=231d OCA], [https://pdbe.org/231d PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=231d RCSB], [https://www.ebi.ac.uk/pdbsum/231d PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=231d ProSAT]</span></td></tr>
</table>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
We report the 2.4 A resolution X-ray structure of a complex in which a small molecule flips a base out of a DNA helical stack. The small molecule is a metalloporphyrin, CuTMPyP4 [copper(II) meso-tetra(N-methyl-4-pyridyl)porphyrin], and the DNA is a hexamer duplex, [d(CGATCG)]2. The porphyrin system, with the copper atom near the helical axis, is located within the helical stack. The porphyrin binds by normal intercalation between the C and G of 5' TCG 3' and by extruding the C of 5' CGA 3'. The DNA forms a distorted right-handed helix with only four normal cross-strand Watson-Crick base pairs. Two pyridyl rings are located in each groove of the DNA. The complex appears to be extensively stabilized by electrostatic interactions between positively charged nitrogen atoms of the pyridyl rings and negatively charged phosphate oxygen atoms of the DNA. Favorable electrostatic interactions appear to draw the porphyrin into the duplex interior, offsetting unfavorable steric clashes between the pyridyl rings and the DNA backbone. These pyridyl-backbone clashes extend the DNA along its axis and preclude formation of van der Waals stacking contacts in the interior of the complex. Stacking contacts are the primary contributor to stability of DNA. The unusual lack of van der Waals stacking contacts in the porphyrin complex destabilizes the DNA duplex and decreases the energetic cost of local melting. Thus extrusion of a base appears to be facilitated by pyridyl-DNA steric clashes.

Structure of DNA-porphyrin complex.,Lipscomb LA, Zhou FX, Presnell SR, Woo RJ, Peek ME, Plaskon RR, Williams LD Biochemistry. 1996 Mar 5;35(9):2818-23. PMID:8608116<ref>PMID:8608116</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 231d" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Lipscomb LA]]
[[Category: Peek ME]]
[[Category: Plaskon RR]]
[[Category: Presnell SR]]
[[Category: Williams LD]]
[[Category: Woo RJ]]
[[Category: Zhou FX]]