Single-molecule fluorescence spectroscopy of biomolecular folding

Single-molecule fluorescence spectroscopy is emerging as an important tool for studying biomolecular folding dynamics. Its usefulness stems from its ability to directly map heterogeneities in folding pathways and to provide information about the energy landscape of proteins and ribonucleic acid (RNA) molecules. Single-molecule fluorescence techniques relevant for folding studies, including methods for trapping and immobilizing molecules, are described and compared in this review. Some emphasis is placed on fluorescence resonance energy transfer, which is particularly useful for studying conformational dynamics of biomolecules. Studies on protein and RNA folding using this methodology are reviewed and set in the more general context of folding science. Finally, some of the interesting future prospects in this field are delineated.