Renewal theory for single-molecule systems with multiple reaction channels.

Some single-molecule systems share a common feature: the system performs different cycles returning after each cycle to the same state. In such systems we deal with renewal processes. Examples include (1) single-molecule enzymatic reactions, (2) membrane transport through single-occupancy channels, (3) single-molecule fluorescence spectroscopy, and (4) motion of molecular motors. The paper is focused on the analysis of such systems by means of the renewal theory. To be more specific, the theory of renewal processes is used to study multivariate distribution functions of the numbers of different events in a given observation time. Our main results are simple formulas derived for the Laplace transforms of the distribution functions. General results are illustrated by consideration of several examples.