Zymogen and procofactor concentrations in physiological biochemical systems (PBS) have not yet been explained. The problem in question is to determine optimal plasma clotting factor (factors II, VII, IX, and X and cofactors V and VIII) concentrations for coagulation system (CS) as a whole. Constrained optimization technique is used to solve this problem. The constraint is determined by the ability of the CS to perform its physiological function--thrombin generation (and hence clot formation)--under vessel injury conditions. The constraint statement is based on the CS dynamics equations. In solving the problem the Lagrange multiplier is used. A hypothesis is advanced that this problem can be solved based on principle of minimum protein consumption subject to an above constraint. The results obtained indicate that the optimal clotting factor concentrations are in good agreement with those measured by biochemical techniques. A comparison between the theoretical results and experimental data lends support for our hypothesis that zymogen and procofactor concentrations in the CS (and, probably, for other biochemical systems) are determined by the principle of minimum protein consumption.