TIME-DEPENDENT CONTROL OF METABOLIC SYSTEMS BY EXTERNAL EFFECTORS

The expression of elasticity coefficients for time-dependent enzyme in hibition/activation by an external effector was initially derived. Onl y a limited number of restrictive assumptions were used, for example, the enzyme was considered to obey Michaelis-Menten kinetics and effect ers were taken to be competitive. Then, a simple metabolic system unde r the control of a time-dependent effector (inhibitor or activator) wa s analysed and the expressions of the control coefficients were obtain ed. In addition, two numerical examples were used to represent the con trol coefficients as functions of time and effector concentration. The results indicate that the control coefficients vary in a relatively l imited range of values; however, for certain intervals of time and of effector concentration local minima or major modifications of the coef ficients may be recorded. The physiological importance of non-steady s tate analysis of metabolic systems controlled by external effecters wa s also discussed. It was stressed that the non-steady state treatment may contribute to creating a more realistic image of the metabolic con trol processes. (C) 1996 Academic Press Limited.