On the role of enzyme kinetic parameters in determining the effectiveness with which channelling can decrease the size of a metabolite pool.

Recently, it has been argued that the phenomenon of direct transfer of intermediate metabolites between adjacent enzymes, also known as metabolic channelling, would not decrease the concentration of those intermediates in the 'bulk' solution. However, this conclusion has been drawn by extrapolation from the results of simulations with a rather restricted set of parameters. We show that, for a number of kinetic cases, the existence of metabolic channelling can decrease the size of the soluble pool of intermediates. When the enzyme(s) 'downstream' of the channel have a catalytic capacity that is large relative to the enzymes 'upstream' of the channel, the decrease of concentration can be substantial (3 orders of magnitude).