Microscopic self-organization in living cells: a study of time matching.

Biochemical subsystems of a living cell may operate with only a few thousand enzyme molecules and their response can be triggered by the entrance of individual molecules of a certain species. This mode of operation is not described by classical chemical kinetics, which deals with large numbers of reacting molecules. Theoretical estimates for the characteristic times of enzymic reactions in small cells and cellular compartments show that any two macromolecules within a micrometer-size volume meet each other each second and that the transit time, required for a mediator molecule to meet a target enzyme, is comparable to the duration of a catalytic round for a single enzyme molecule. When these conditions are satisfied, an enzymic subsystem represents a coherent molecular network with persistent strong temporal correlations between the catalytic events of individual enzyme molecules.