title: Triplex DNA structures.
abstract: A DNA triplex is formed when pyrimidine or purine bases occupy the major groove of the DNA double Helix forming Hoogsteen pairs with purines of the Watson-Crick basepairs. Intermolecular triplexes are formed between triplex forming oligonucleotides (TFO) and target sequences on duplex DNA. Intramolecular triplexes are the major elements of H-DNAs, unusual DNA structures, which are formed in homopurine-homopyrimidine regions of supercoiled DNAs. TFOs are promising gene-drugs, which can be used in an anti-gene strategy, that attempt to modulate gene activity in vivo. Numerous chemical modifications of TFO are known. In peptide nucleic acid (PNA), the sugar-phosphate backbone is replaced with a protein-like backbone. PNAs form P-loops while interacting with duplex DNA forming triplex with one of DNA strands leaving the other strand displaced. Very unusual recombination or parallel triplexes, or R-DNA, have been assumed to form under RecA protein in the course of homologous recombination.
authors.affiliation: Center for Advanced Biotechnology, Boston University, Massachusetts 02215, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Frank-Kamenetskii
authors.forename: S M
authors.initials: SM
authors.lastname: Mirkin
mesh_terms: D000818:Animals; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D004355:Drug Stability; D006801:Humans; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D009696:Nucleic Acids / Q000737:chemistry; D010455:Peptides / Q000737:chemistry; D011995:Recombination, Genetic
chemical_list: D009696:Nucleic Acids; D010455:Peptides; C051802:triplex DNA; D004247:DNA