Effect of channeling on reaction cascades with competing reactions.

<p>(a) Product formation velocity of the nonchanneled system, <i>v</i><sub><i>non</i></sub>, decreases as the degradation or consumption rate of intermediates, <i>k</i><sub>deg</sub>, increases. (b) Reaction velocity of the nonchanneled system falls off for increasing ‘degree of reversibility’ of the first reaction in the cascade, . In this case the reaction is in lieu of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0172673#pone.0172673.e001" target="_blank">Eq (1a)</a>. In both plots <i>v</i><sub><i>non</i></sub> is compared to the velocity of the channeled system, <i>v</i><sub><i>ch</i></sub>. The concentrations of enzymes and enzyme-enzyme complexes are equal in both systems on both panels, <i>i.e.</i> [E<sub><i>i</i></sub>] = [E<sub>1</sub>] = [E<sub>2</sub>] = [E<sub>12</sub>]; in panel (b) the ratio <i>v</i><sub><i>non</i></sub>/<i>v</i><sub><i>ch</i></sub> is independent of [E<sub><i>i</i></sub>]. Substrate concentration [S] = 90 nM, the degree of diffusion control is <i>γ</i><sub>1</sub> = <i>γ</i><sub><i>ch</i></sub> = 1 (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0172673#pone.0172673.e021" target="_blank">Eq (10)</a>), and the rate constants are the same as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0172673#pone.0172673.g001" target="_blank">Fig 1</a>. Thin dotted line denotes <i>v</i><sub><i>ch</i></sub> = <i>v</i><sub><i>non</i></sub>.</p>