The kinetic profile of enzyme X is measured both in the presence and absence of
ID: 83288 • Letter: T
Question
The kinetic profile of enzyme X is measured both in the presence and absence of an inhibitor. (a) For the Michaels Mention equation below, please plot the curve of v vs. [S]. Please define the meaning of k_cat and K_m by making reference to the curve. v = V_max[S]/K_m + [S] (b) Based on the data table above, what type of inhibitor is used in the experiment? Please explain your answer. (c) Suppose you engineer a mutation in the active site of enzyme X so that it binds to a substrate 100-fold stronger while all other aspects of the catalysis remains unchanged. Please compare the V_max and K_m of the mutant to that of the wild-type. Please explain your answer.Explanation / Answer
Kcat is referred as turnover number, there fore according to graph Kcat = 45M/min/250 = 0.15 M/min since Kcat always given in per secso 0.18/60 = 0.003M/sec
Km = Half of the substrate concentration at which rate of maximum velocity is half of Vmax = 250M/2 = 125 M.
2. competitive inhibitors as it increase Km value and decrease affinity while Vmax stays the same
Vmax reaches at 300 M so 300/2 = 150 M since km is higher then without inhibitor thus it is competitive inhibitor.
3. It is consider that at low Km value ES complex do not break easily thus enzyme bind to a substrate for a long duration and therefore it ican be said that when Km is low the enzyme has higher affinity for the substrate. so if mutation allow enzyme to bind 100 fold stronger it suggest ES complex does not break easily and thus it possess low km. Thus only little bit of substrate is required in the solution to reach Vmax/2.
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