title: Triple helix stabilization by covalently linked DNA-bisbenzimidazole conjugate synthesized by maleimide-thiol coupling chemistry.
abstract: Tethering of BBZPNH2, an analogue of the Hoechst 33258, with a 14 nucleotide long DNA sequence with the help of succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate (SMCC), a heterobifunctional crosslinking reagent, using DMF/ water as solvent yields a conjugate which effectively stabilizes the triple helix. The above conjugate was hybridized with 26 bp long double stranded (ds) DNA having 14 bp long polypurine-polypyrimidine stretch to form a pyrimidine motif triple helix. The above conjugate increases the thermal stability of both the transitions, that is, triple helix to double helix by 12 degrees C and double helix to single strand transition by 16 degrees C for the triple helix formed with conjugated TFO over the triple helix made from non-conjugated TFO. Fluorescence and circular dichroism spectra recorded at different temperatures confirm the presence of minor groove binding bisbenzimidazole in the AT-rich minor groove of dsDNA even after the major groove bound TFO separates out.
authors.affiliation: Dr. B. R. Ambedkar Center for Biomedical Research, University of Delhi, Delhi 110007, India.
authors.forename: Akash K
authors.initials: AK
authors.lastname: Jain
authors.forename: Satish Kumar
authors.initials: SK
authors.lastname: Awasthi
authors.forename: Vibha
authors.initials: V
authors.lastname: Tandon
mesh_terms: D001562:Benzimidazoles / Q000138:chemical synthesis / Q000737:chemistry*; D006690:Bisbenzimidazole / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000737:chemistry*; D002942:Circular Dichroism; D004247:DNA / Q000138:chemical synthesis / Q000737:chemistry*; D008301:Maleimides / Q000737:chemistry*; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry; D013329:Structure-Activity Relationship; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013696:Temperature
chemical_list: D001562:Benzimidazoles; D008301:Maleimides; D009841:Oligonucleotides; D013438:Sulfhydryl Compounds; C051802:triplex DNA; C043592:maleimide; D004247:DNA; D006690:Bisbenzimidazole