Nonexponential kinetics of a single tRNA Phe molecule under physiological conditions

Abstract
The fluorescence decay functions of individual, specifically labeled tRNAPhe molecules exhibit nonexponential character as a result of conformational dynamics occurring during the measurement on a single molecule. tRNAPhe conformational states that interchange much more slowly are evidenced by the distribution of lifetimes observed for many individual molecules. A structural model for the nonexponential decay indicates that the tRNAPhe–probe adduct fluctuates between two states, one of which provides conditions that quench the probe fluorescence.