Parallel-stranded DNA with Hoogsteen base pairing stabilized by a trans-[Pt(NH3)2]2+ cross-link: characterization and conversion into a homodimer and a triplex.
The oligonucleotides 5'-d(TTTTCTTTTG) and 5'-d(AAAAGAAAAG) were cross-linked with a trans-[Pt(NH3)2]2+ entity via the N7 positions of the 3'-end guanine bases to give parallel-stranded (ps) DNA. At pH 4.2, CD and NMR spectroscopy indicate the presence of Hoogsteen base pairing. In addition, temperature-dependent UV spectroscopy shows an increase in melting temperature for the platinated duplex (35 degrees C) as compared to the non-platinated, antiparallel-stranded duplex formed from the same oligonucleotides (21 degrees C). A monomer-dimer equilibrium for the platinated 20mer is revealed by gel electrophoresis. At pH 4.2, addition of a third strand of composition 5'-d(AGCTTTTCTTTTAG) to the ps duplex leads to the formation of a triple helix with two distinct melting points at 38 degrees C (platinum cross-linked Hoogsteen part) and 21 degrees C (Watson-Crick part), respectively.
Müller
J
J
Fachbereich Chemie, Universität Dortmund, Germany.
Drumm
M
M
Boudvillain
M
M
Leng
M
M
Sletten
E
E
Lippert
B
B
D020029:Base Pairing / Q000187:drug effects*; D001483:Base Sequence; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D002945:Cisplatin / Q000494:pharmacology*; D003432:Cross-Linking Reagents / Q000494:pharmacology*; D004247:DNA / Q000138:chemical synthesis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019281:Dimerization; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009691:Nucleic Acid Denaturation; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D013696:Temperature
D003432:Cross-Linking Reagents; D009838:Oligodeoxyribonucleotides; C051802:triplex DNA; C034697:transplatin; D004247:DNA; D002945:Cisplatin