The cellular distribution of free and bound glycolytic enzymes in vivowas estimated by means of a model based on previously determined association constants for individual binding interactions and in vivoprotein concentrations. The calculations revealed that a significant proportion of the enzymes would be either associated with F-actin, or bound in binary enzyme-enzyme complexes in vivo. An analysis of the relative concentration, and relative activity, of F-actin-bound enzymes suggested that a complete glycolytic complex, composed of all enzymatic steps from phosphofructokinase (PFK) to lactate dehydrogenase (LDH) does not exist. This was indicated by a very low concentration of F-actin-associated phosphoglycerate kinase (PGK) and by a very low activity of F-actin bound aldolase and PGK; this model showed that aldolase and PGK would be absent from any F-actin bound complex. An analysis of soluble enzyme-enzyme associations indicated that formation of binary enzyme complexes may lead to an increased overall flux through glyceraldehyde 3-phosphate dehydrogenase and LDH, but would serve to decrease flux through PFK and aldolase. A 1·4-fold activation of PFK, which occurs when the soluble enzyme binds to F-actin, suggested that reversible binding of PFK to F-actin may represent a novel cellular mechanism for controlling glycolytic flux during periods of increased metabolic demand by controlling the key regulatory enzyme of glycolysis.
Journal of Theoretical Biology
Department of Biology

Brooks, S.P.J. (Stephen P.J.), & Storey, K. (1991). A quantitative evaluation of the effect of enzyme complexes on the glycolytic rate in vivo: Mathematical modeling of the glycolytic complex. Journal of Theoretical Biology, 149(3), 361–375. doi:10.1016/S0022-5193(05)80311-X