Triplex mediated delivery of a platinum complex to a specific DNA target site.
Tethering an ethylene diamine linker to the 5' terminus of an oligothymidine sequence provides a site for complexation with K(2)PtCl(4). Due to the low reactivity of dT toward a platinum source, we chose dT(8) and dT(15) as our initial synthetic targets for platination. Post-synthetic reaction of the platinum reagent with the diamino oligothymidine generates the diamino dichloro platinum-DNA conjugate that can be used for DNA duplex targeting by oligodeoxyncleotide-mediated triplex formation. The dT(8) sequence is not sufficiently long to facilitate triplex formation and Pt-cross-linking, whereas with a dT(15) sequence cross-linking between the third strand and the duplex occurs exclusively with the duplex target strand directly involved in triplex formation. No examples of cross-linking to the complementary target strand, or of cross-linking to both target strands are observed. Most efficient cross-linking occurs when the dinucleotide d(GpG) is present in the target strand and no cross-linking occurs with the corresponding 7-deazaG dinucleotide target. Cross-linking is also observed when dC or dA residues are present in the target strand, or even with a single dG residue, but it is not observed in any cases to dT residues. Triplex formation provides the ability to target specific sequences of double-stranded DNA and the orientational control arising from triplex formation is sufficient to alter the binding preferences of platinum. Conjugates of the type described here offer the potential of delivering a platinum complex to a specific DNA site.
Department of Chemistry, University of Delhi, Delhi 110 007, India.
Sunil K
SK
Sharma
Larry W
LW
McLaughlin
D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015394:Molecular Structure; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017671:Platinum Compounds / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology*; D013379:Substrate Specificity
D009838:Oligodeoxyribonucleotides; D017671:Platinum Compounds; C051802:triplex DNA; D004247:DNA