A simple summation theorem describes the control of fluxes in ‘ideal’ metabolic pathways. This paper shows how this theorem and the control properties of a pathway change when direct transfer of intermediates and/or sequestration of metabolites involved in moiety conservations (by enzymes present at high concentrations) take place. The derived generalized summation theorem quantifies the extent to which metabolite sequestration decreases and direct metabolite transfer can increase the control exerted by enzymes on the flux. The implications of metabolite channelling for the control of fluxes are discussed quantitatively.
