8. The drug ibuprofen inhibits the enzyme cyclooxygenase, which generates prostaglandins. The Lineweaver-Burke analysis results of an enzyme activity assay are shown in the figure below. Briefly, 15 µM cyclooxygenase was added to solutions of increasing substrate concentration. Two assays were performed. In one, only substrate and enzyme were present. In the other, 75 µM ibuprofen was included. The equations of the lines for the two LB analyses are shown on the graph. Pay attention to the units on the two axes. 0.0091 0.008 0.007 0.006- With 75 uM Ibuprofen: y=(0.69)x+(0.00085) 0.005 0.004 With no drug: 0.003- y=(0.14)x+(0.00084) 0.002- 0.001 0.006 0.008 0.010 0.012 1/[S] (1/µM) a) What is the mechanism of inhibition? b) b) Calculate kcat, the catalytic rate constant of the enzyme action c) Calculate KM with and without the drug. d) Calculate the drug-binding equilibrium constant, Kdrug. 1/Rate (s/µM)
8. The drug ibuprofen inhibits the enzyme cyclooxygenase, which generates prostaglandins. The Lineweaver-Burke analysis results of an enzyme activity assay are shown in the figure below. Briefly, 15 µM cyclooxygenase was added to solutions of increasing substrate concentration. Two assays were performed. In one, only substrate and enzyme were present. In the other, 75 µM ibuprofen was included. The equations of the lines for the two LB analyses are shown on the graph. Pay attention to the units on the two axes. 0.0091 0.008 0.007 0.006- With 75 uM Ibuprofen: y=(0.69)x+(0.00085) 0.005 0.004 With no drug: 0.003- y=(0.14)x+(0.00084) 0.002- 0.001 0.006 0.008 0.010 0.012 1/[S] (1/µM) a) What is the mechanism of inhibition? b) b) Calculate kcat, the catalytic rate constant of the enzyme action c) Calculate KM with and without the drug. d) Calculate the drug-binding equilibrium constant, Kdrug. 1/Rate (s/µM)
Biochemistry
9th Edition
ISBN:9781319114671
Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
Chapter1: Biochemistry: An Evolving Science
Section: Chapter Questions
Problem 1P
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![8. The drug ibuprofen inhibits the enzyme cyclooxygenase, which generates prostaglandins. The Lineweaver-Burke
analysis results of an enzyme activity assay are shown in the figure below. Briefly, 15 µM cyclooxygenase was
added to solutions of increasing substrate concentration. Two assays were performed. In one, only substrate and
enzyme were present. In the other, 75 µM ibuprofen was included. The equations of the lines for the two LB
analyses are shown on the graph. Pay attention to the units on the two axes.
0.009-
0.008 -
0.007-
With 75 uM Ibuprofen:
y=(0.69)x+(0.00085)
0.006-
0.005-
0.004
With no drug:
0.003-
y=(0.14)x+(0.00084)
0.002-
0.001-
0.008
0.006
1/[S] (1/µM)
0.010
0.012
a) What is the mechanism of inhibition?
b) b) Calculate kcat, the catalytic rate constant
of the enzyme action
c) Calculate KM with and without the drug.
d) Calculate the drug-binding equilibrium
constant, Kdrug.
e) Calculate the free energy of drug binding,
AGbind ° .
1/Rate (s/µM)](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F551768ff-ae68-473c-9ced-46521c2e3195%2F63d86f9b-349c-4e2c-bef9-f1ea825ce321%2F9e06je_processed.jpeg&w=3840&q=75)
Transcribed Image Text:8. The drug ibuprofen inhibits the enzyme cyclooxygenase, which generates prostaglandins. The Lineweaver-Burke
analysis results of an enzyme activity assay are shown in the figure below. Briefly, 15 µM cyclooxygenase was
added to solutions of increasing substrate concentration. Two assays were performed. In one, only substrate and
enzyme were present. In the other, 75 µM ibuprofen was included. The equations of the lines for the two LB
analyses are shown on the graph. Pay attention to the units on the two axes.
0.009-
0.008 -
0.007-
With 75 uM Ibuprofen:
y=(0.69)x+(0.00085)
0.006-
0.005-
0.004
With no drug:
0.003-
y=(0.14)x+(0.00084)
0.002-
0.001-
0.008
0.006
1/[S] (1/µM)
0.010
0.012
a) What is the mechanism of inhibition?
b) b) Calculate kcat, the catalytic rate constant
of the enzyme action
c) Calculate KM with and without the drug.
d) Calculate the drug-binding equilibrium
constant, Kdrug.
e) Calculate the free energy of drug binding,
AGbind ° .
1/Rate (s/µM)
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