Understanding how enzymes function requires a thorough characterization of
enzymatic dynamics. Traditional enzymatic assays average over an ensemble of molecules,
making it difficult to detect reaction intermediates and conformational fluctuations of the
enzyme. These problems can be overcome by observing enzymes functioning in real time
on the single-molecule level. This chapter describes recent research efforts to measure singlemolecule
enzyme kinetics and observe the structural dynamics of enzymes and discusses new
approaches to study multiprotein complexes on the single-molecule level.