1lex
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(New page: 200px<br /><applet load="1lex" size="450" color="white" frame="true" align="right" spinBox="true" caption="1lex, resolution 2.250Å" /> '''STRUCTURE OF A DICA...)
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Revision as of 00:46, 25 November 2007
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STRUCTURE OF A DICATIONIC MONOIMIDAZOLE LEXITROPSIN BOUND TO DNA (ORIENTATION 1)
Overview
An X-ray crystal structure has been solved of the complex of a dicationic, lexitropsin with a B-DNA duplex of sequence CGCGAATTCGCG. The lexitropsin, is identical to netropsin except for replacement of the first, methylpyrrole ring by methylimidazole, converting a =CH- to =N-. Crystals, are isomorphous with those of the DNA dodecamer in the absence of drug., Although the =N- for =CH- substitution was intended to make that locus on, the drug molecule compatible with a G.C base pair, electrostatic, attraction for the two cationic ends of the drug predominates, and this, lexitropsin binds to the same central AATT site as does the parent, netropsin. But unlike netropsin, this lexitropsin exhibits end-for-end, disorder in the crystal. Both orientations were refined separately to, completion. Final residual errors at 2.25 A resolution for the 2358, reflections above 2 sigma in F are R = 0.165 for one orientation (LexA), with 37 water molecules and 0.164 for the inverted drug orientation (LexB), with 40 water molecules. This molecular disorder is probably attributable, to a weakening of binding to the AATT site occasioned by the, imidazole-for-pyrrole substitution.
About this Structure
1LEX is a Protein complex structure of sequences from [1] with ILT as ligand. Full crystallographic information is available from OCA.
Reference
Structure of a dicationic monoimidazole lexitropsin bound to DNA., Goodsell DS, Ng HL, Kopka ML, Lown JW, Dickerson RE, Biochemistry. 1995 Dec 26;34(51):16654-61. PMID:8527438
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