Question

4. Experiment: Enzyme Kinetics

Given the following kinetic data, prepare a Lineweaver Burk mechanism of action plot for the inhibitor Compound 1 with the enzyme Abc1. What kind of inhibitor is Compound 1 with respect the substrate of Abc1, SubstrateX? Based on this result, do you think that Compound 1 is structurally similar to SubstrateX, or structurally dissimilar to SubstrateX?

	Velocity (µM/min)
[SubstrateX] (µM)	0 µM Compound 1	2 µM Compound 2	5 µM Compound 1
10	15	6	3.5
15	20	9	5
20	24	11	7
30	33	18	11
50	42	30	20
70	48	42	29
100	50	48	40

Answer 1

the plot of 1/V vs 1/S for without inhibitor, with inhibitors at different concentrations is shown below

from 1/V= (KM/Vmax)*1/S +1/Vmax

the plot of 1/V vs 1/S gives a straight line whose slope is KM/vmax and intercept 1/Vmax

without any inhibition, 1/Vmax = 0.0137 and Vmax = 72.99 uM/min and KM/vmax = 0.5353

KM= 72.99*0.5353=39.07 uM

since the intercepts for all the three cases is different this is a case of mixed inhibition. The inhibitor prevents catalysis. Hence the inhibitor is structurally same as enzyme,