Influence of base dynamics on the conformational properties of DNA: Observation of static conformational states in rigid duplexes at 77 K

The fluorescence decay of rigid 2-aminopurine (AP)-labeled duplexes at 77 K are examined in order to investigate the nature of the conformational states that give rise to the heterogeneous decay of AP and the roles of base dynamics in populating these states. The results have shown that the highly stacked geometry that gives rise to the very short decay time of AP-labeled DNA can be attained only through thermal motion of the bases.