Understanding dynamic disorder fluctuations in single-molecule enzymatic reactions

Single-molecule studies of enzymatic reactions reveal fluctuations in the reaction rate, which cannot be explained by classic Markovian dynamics. This dynamic disorder is attributed to slow transitions in enzyme conformations that take place over timescales longer than reaction cycle times. In this review we summarize current theoretical models for reaction kinetics in fluctuating, single enzyme systems. Also examined are some of the implications of single-molecule fluctuations for reaction rates in systems such as cells or biosensors that contain a moderate number of molecular copies. We conclude that the dynamic disorder in single-molecule enzyme systems is well-described by available models. However, more work is required to study the effect of single-molecule fluctuations on finite systems over limited periods of time.