title: Triple-helical polynucleotides. Mixed triplexes of the poly(uridylic acid)-poly(adenylic acid)-poly(uridylic acid) class.
abstract: By the techniques of interferon induction in primary rabbit kidney cells "superinduced" with metabolic inhibitors, ultraviolet absorbance-temperature profiles, sensitivity to pancreatic ribonuclease A, and sucrose velocity gradient ultracentrifugation, a number of reactions between double-helical RNA and single-stranded RNA or DNA homopolymers were investigated. The polymers involved in these studies were poly(adenylic acid), poly(uridylic acid), poly(ribothymidylic acid), poly(5-bromouridylic acid), poly(deoxythymidylic acid), poly(deoxyuridylic acid), poly(3-methyluridylic acid), poly(2'-O-methyluridylic acid), and poly(2'-azido-2'-deoxyuridylic acid). Two different reaction courses, both leading to the formation of triple helices, were noted: (1) poly(Ux)-poly(A) + poly(Uy) leads to poly(Ux)-poly(A)-poly(Uy) if the Tm of poly(Ux)-poly(A) was higher than the Tm of poly(Uy)-poly(A); (2) poly(Ux)-poly(A) + poly(Uy) leads to poly(Uy)-poly(A)-poly(Ux) if the Tm of poly(Ux)-poly(A) was lower than the Tm of poly(Uy)-poly(A). In these equations, the homopolymer written to the left of poly(A) implies Watson-Crick hydrogen bonding whereas the polymer to the right of poly(A) is involved in Hoogsteen hydrogen bonding.
mesh_terms: D000818:Animals; D001681:Biological Assay; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004357:Drug Synergism; D007369:Interferon Inducers / Q000494:pharmacology*; D007372:Interferons / Q000096:biosynthesis; D009690:Nucleic Acid Conformation; D011061:Poly A; D011072:Poly U; D011119:Polynucleotides / Q000494:pharmacology; D011817:Rabbits; D012260:Ribonucleases; D013329:Structure-Activity Relationship; D013696:Temperature
chemical_list: D007369:Interferon Inducers; D011119:Polynucleotides; D003609:Dactinomycin; D011061:Poly A; D011072:Poly U; D007372:Interferons; D003513:Cycloheximide; D012260:Ribonucleases