Influence of base dynamics on the conformational properties of DNA: Observation of static conformational states in rigid duplexes at 77 K.
Time-resolved fluorescence of 2-aminopurine-labeled DNA duplexes at 77 K reveals the relationship between base dynamics and the conformational heterogeneity that results in the well-known multiexponential fluorescence decay at room temperature. The conformation that exhibits rapid interbase charge transfer at room temperature is not populated in the frozen duplex at 77 K; this geometry is accessed by thermal motion of the bases, it is not a minimum energy structure of the duplex. Three photophysically distinct conformational states persist in the frozen duplex; these are minimum energy structures and do not interconvert at room temperature on the time scale of the 2-aminopurine excited-state lifetime.
Neely
Robert K
RK
School of Chemistry and the Collaborative Optical Spectroscopy, Micromanipulation and Imaging Centre (COSMIC), The University of Edinburgh, Edinburgh EH9 3JJ, UK.
Jones
Anita C
AC
D001483:Base Sequence; D004247:DNA / Q000737:chemistry*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D013050:Spectrometry, Fluorescence; D013696:Temperature
D004247:DNA