[jelinir]

Hi. I have a question on complexe reaction as a homework.please help to answer it

problem 23 of atkins' physical chemistry

23.26 In general, the catalytic efficiency of an enzyme depends on the pH of the medium in which it operates. One way to account for this behaviour is to propose that the enzyme and the enzyme-substrate complex are active only in specific protonation states. This situation can be summarized by the following mechanism: 15 EH + S _ ESH ka , ka ESH E +P kb EH _ E- + H+ EH2+ _ EH + H+ ESH _ ES- + H+ ESH2 _ ESH + H+ in which only the EH and ESH forms are active. (a) For the mechanism above, show that with where vmax and KM correspond to the form EH of the enzyme. (b) For pH values ranging from 0 to 14, plot v max against pH for a hypothetical reaction for which vmax = 1.0 10-6 mol dm-3 s-1, KES,b = 1.0 10-6 mol dm-3 and KES,a = 1.0 10-8. Is there a pH at which vmax reaches a maximum value? If so, determine the pH. (c) Redraw the plot in part (b) by using the same value of vmax, but KES,b = 1.0 10-4 mol dm-3 and KES,a = 1.0 10-10 mol dm-3. Account for any differences between this plot and the plot from part (b).