Rupture force changes between the third strand and the double strand within an oligonucleotide-directed triplex in the presence of intercalative molecules

摘要

The rupture force changes to separate the third strand from the duplex within an oligonucleotide-directed triplex (triplex DNA) were measured in the presence of small DNA binding molecules by means of atomic force spectroscopy. Rupture force histograms revealed a rupture force of 44.3 ±0.4 pN to separate the third strand from duplex DNA in pure buffer solution at a rupture velocity of 400 nm/s. In 30 μM of Ru(bipy)_2(dppz)~(2+) buffer solution an increase of rupture force to 57±2.2 pN was observed. For 30 μM Ru(phen)_2(dppz)~(2+) a rupture force of 65.1±3.9 pN was determined. These results show that both intercalative molecules increase the stability of triplex DNA significantly.