View source for 263d

[[Image:263d.jpg|left|200px]]

 {{Structure
|PDB= 263d |SIZE=350|CAPTION= <scene name='initialview01'>263d</scene>, resolution 2.200&Aring;
|SITE= 
|LIGAND= <scene name='pdbligand=DA:2&#39;-DEOXYADENOSINE-5&#39;-MONOPHOSPHATE'>DA</scene>, <scene name='pdbligand=DC:2&#39;-DEOXYCYTIDINE-5&#39;-MONOPHOSPHATE'>DC</scene>, <scene name='pdbligand=DG:2&#39;-DEOXYGUANOSINE-5&#39;-MONOPHOSPHATE'>DG</scene>, <scene name='pdbligand=DT:THYMIDINE-5&#39;-MONOPHOSPHATE'>DT</scene>, <scene name='pdbligand=TBZ:2&#39;&#39;-(4-METHOXYPHENYL)-5-(3-AMINO-1-PYRROLIDINYL)-2,5&#39;,2&#39;,5&#39;&#39;-TRI-BENZIMIDAZOLE'>TBZ</scene>
|ACTIVITY= 
|GENE= 
|DOMAIN=
|RELATEDENTRY=
|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=263d FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=263d OCA], [http://www.ebi.ac.uk/pdbsum/263d PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=263d RCSB]</span>
}}

'''ISOHELICITY AND PHASING IN DRUG-DNA SEQUENCE RECOGNITION: CRYSTAL STRUCTURE OF A TRIS(BENZIMIDAZOLE)-OLIGONUCLEOTIDE COMPLEX'''


==Overview==
The crystal structure is reported of a tris(benzimidazole) analogue of the minor-groove drug Hoechst 33258 bound to the sequence d(CGCAAATTTGCG)2. The structure has been refined to an R factor of 17.4% at a resolution of 2.2 A. The ligand covers approximately 7 1/2 base pairs, including the 5'-AAATTT central sequence. This has an exceptionally narrow minor-groove width, together with high propeller twists for individual base pairs. The ligand has a highly twisted structure, with an overall twist of 50 degrees between aromatic rings. All three benzimidazole subunits are in register with the DNA, and there is a symmetric group of six hydrogen bonds between ligand and A.T base-pair edges. By contrast, the ligand does not show an optimal isohelical fit to the DNA. The correct phasing of drug and DNA base pairs is ensured by a number of changes to the DNA such that the central 5'-AAATTT region is slightly unwound relative to the structures of other noncovalent minor-groove drug complexes.

==About this Structure==
263D is a [[Protein complex]] structure of sequences from [http://en.wikipedia.org/wiki/ ]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=263D OCA]. 

==Reference==
Isohelicity and phasing in drug--DNA sequence recognition: crystal structure of a tris(benzimidazole)--oligonucleotide complex., Clark GR, Gray EJ, Neidle S, Li YH, Leupin W, Biochemistry. 1996 Oct 29;35(43):13745-52. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/8901516 8901516]
[[Category: Protein complex]]
[[Category: Clark, G R.]]
[[Category: Gray, E J.]]
[[Category: Leupin, W.]]
[[Category: Li, Y H.]]
[[Category: Neidle, S.]]
[[Category: b-dna]]
[[Category: complexed with drug]]
[[Category: double helix]]

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