CChheemm 44334433 Quiz Nov 2009 Name : Answer each of the following five parts for a total of 100 points. 1 (i) Provide the mechanistic arrows for both steps in the enzymatic process shown below: (ii) For the enzymatic reaction on the right there are two possible mechanisms. Draw the arrows for each and explain how pH measurements might be used to identify which mechanism occurs.: (iii) In the diagram to the right, the left panel shows a substrate bound in the active site of the enzyme found in plants. This enzyme also exists in mutant form, and is readily inhibited by 'Roundup', a widely used herbicide. For the kinetic analysis shown underneath identify, giving your reasoning, which line belongs to which of the four possibilities: E(wild-type)+S ; E(mutant) +S; E(wild-type)+S + I ; E(mutant) +S + I A B C(iv) Explain what the pH dependence plot on the right tells us about the enzymatic reaction shown and predict the effect on the kinetics of changing the circled serine residue to valine (v) In the plot shown on the right the enzyme kinetic data was obtained for the normal enzyme reacting with the normal substrate in the absence of inhibitor, i.e. the drug. Determine a value for VMAX and KM. On the diagram that is given draw the plot for the reaction of a) mutant enzyme + normal substrate b) normal enzyme + substrate+ Drug normal enzyme active site mutant enzyme active
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