The fluctuations of the enzymatic reaction rate in the case of competing bounding of the inhibitor to the enzyme are determined. It is considered that the molecules of the enzyme are immobilized on the carrier that is bounded with the solution containing substrate and inhibitor. Within the solution the substrate and inhibitor are being homogeneously bounded to the enzyme after which the substrate-enzyme and inhibitor-enzyme complexes are dissolving to the free enzyme, product and inhibitor dispatched into the solution. No diffusion limitations are considered.

The processes of inhibitor-enzyme complex formation and its dissolving to the free enzyme and inhibitor are rather fast. The determination of the enzymatic reaction rate fluctuations is equivalent to the calculation of the amount of the substrate-enzyme complex on the carrier taking into consideration probable bounding of the inhibitor to the active locus of the enzyme.

The calculations show that the interdependence between the fluctuations of the enzymatic reaction rate and substrate concentration is linearly in the case of low substrate concentrations. However, higher substrate concentrations result to decrease of fluctuations. The maximum fluctuations occur when the substrate concentration is equal to Michaelis constant. The occurrence of the inhibitor results to the decrease in fluctuations? intensification rate in the case of rather low substrate concentrations as well as to the decrease in fluctuations rate in the case of higher substrate concentrations.