Channelling can affect concentrations of metabolic intermediates at constant net flux: artefact or reality?
We show that if a metabolic intermediate is directly transferred ('channelled') from an enzyme that catalyses its production to another that uses it as substrate, there is no change in its free concentration compared with a system with the same net flux in which there is no direct transfer. Thus the widespread idea that channelling provides a mechanism for decreasing metabolite concentrations at constant flux is false. Results from computer simulation that suggest otherwise [Mendes, P., Kell, D. B. & Westerhoff, H. V. (1992) Eur. J. Biochem. 204, 257-266] are artefacts either of variations in flux or of alterations in opposite directions of the activities of the relevant enzymes.
Cornish-Bowden
A
A
Laboratoire de Chimie Bactérienne, Centre National de la Recherche Scientifique, Marseille, France.
Cárdenas
M L
ML
D016477:Artifacts; D002384:Catalysis; D003198:Computer Simulation; D004798:Enzymes / Q000378:metabolism*; D007700:Kinetics; D008956:Models, Chemical
D004798:Enzymes