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New page: left|200px<br /><applet load="231d" size="350" color="white" frame="true" align="right" spinBox="true" caption="231d, resolution 2.400Å" /> '''STRUCTURE OF A DNA-...
 
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[[Image:231d.jpg|left|200px]]<br /><applet load="231d" size="350" color="white" frame="true" align="right" spinBox="true"
caption="231d, resolution 2.400&Aring;" />
'''STRUCTURE OF A DNA-PORPHYRIN COMPLEX'''<br />


==Overview==
==STRUCTURE OF A DNA-PORPHYRIN COMPLEX==
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.
<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.


==About this Structure==
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>
231D is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/ ] with <scene name='pdbligand=PCU:'>PCU</scene> and <scene name='pdbligand=NA:'>NA</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=231D OCA].


==Reference==
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=8608116 8608116]
</div>
[[Category: Protein complex]]
<div class="pdbe-citations 231d" style="background-color:#fffaf0;"></div>
[[Category: Lipscomb, L.A.]]
== References ==
[[Category: Peek, M.E.]]
<references/>
[[Category: Plaskon, R.R.]]
__TOC__
[[Category: Presnell, S.R.]]
</StructureSection>
[[Category: Williams, L.D.]]
[[Category: Large Structures]]
[[Category: Woo, R.J.]]
[[Category: Lipscomb LA]]
[[Category: Zhou, F.X.]]
[[Category: Peek ME]]
[[Category: NA]]
[[Category: Plaskon RR]]
[[Category: PCU]]
[[Category: Presnell SR]]
[[Category: complexed with drug]]
[[Category: Williams LD]]
[[Category: double helix]]
[[Category: Woo RJ]]
[[Category: flipped-out bases]]
[[Category: Zhou FX]]
[[Category: right handed dna]]
 
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Latest revision as of 07:43, 13 August 2026

STRUCTURE OF A DNA-PORPHYRIN COMPLEX

231d, resolution 2.40Å

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