Sensitivity of Ru(phen)(2)dppz (2+) light switch emission to ionic strength, temperature, and DNA sequence and conformation

摘要: The luminescence of DNA-bound [Ru(phen)(2)dppz](2+) is shown to be highly sensitive environmental conditions such as ionic strength, temperature, and the sequence secondary structure nucleic acid, although not bulky DNA substituents in major groove. Each enantiomer has two characteristic lifetimes with any polynucleotide their relative amplitudes vary a function binding ratio. For [poly(dA-dT)](2) model sequence, longer lifetime for Delta-[Ru(phen)(2)dppz](2+) been assigned canted intercalation complex shorter ascribed symmetric intercalation. At fixed ratio, amplitude increases increasing without significant change lifetimes. Increasing temperature similar effect, but also affects In general, emission strongest AT-rich polynucleotides higher-order structures, intensity single-stranded < duplex triplex. However, sequence-context influence photophysics since [poly(dA)]center dot[poly(dT)] significantly higher than or [poly(rA)] u [poly(rU)]. strong different on acid-bound reflects subtle heterogeneities that are inherent elements recognition by small molecules, amplified large changes caused differential exposure dppz nitrogens groove hydration.