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michealis-menten_1.pptx
1. Group 1 – Interface of Chemistry and
Biology
Quantitative Analysis of Enzyme
Activity
Scott Sutherland
Stony Brook University
Steven Glynn
Stony Brook University
Lindsay Hinkle
Harvard University
Rosa Veguilla
Harvard University
Leon Dickson
Howard University
Kevin Jones
Howard University
2. Goals and Objectives
Learning Goal:
Students will have the ability to manipulate, interpret, and
produce visual representations of data describing kinetic
properties of enzymes
Learning Objectives:
Students will be able to:
• Determine reaction rates from experimental time-course
data
• Produce the Michaelis-Menten plot from experimental data
• Interpret changes in reaction conditions from different
Michaelis-Menten plots
• Design an experiment to generate data for a Michaelis-
3. Who you are:
Upper level Biochemistry major who has
completed Calculus and Introductory
Chemistry and Biology
We’re halfway through a lecture in
steady-state enzyme kinetics.
See tip sheet for topics you have
covered.
4. HIV-1 protease is crucial for the replication of
HIV
Inhibiting the activity of HIV-
I protease is a strategy for
combating the virus
The first step in designing an
inhibitor is to understand the
kinetic properties of the enzyme
(necessary for
HIV replication)
6. Choose the components of the
HIV-1 protease reaction
HIV-1 protease
Viral
polypeptide
HIV-1 protease/
Viral polypeptide
complex
Cleaved viral
polypeptides
7. An enzyme’s response to substrate can
be visualized using the Michaelis-Menten
plot
Michaelis-
Menten Equation
Substrate concentration
(μM)
Initial
reaction
velocity
(μM
sec
-1
)
Vmax
KM
Vmax/2
8. Activity 1
Match the experimental data to the
corresponding line on the plot of time-
course reactions
Remember that the slope of the time-course
corresponds to the rate of the reaction at a given
substrate concentration
10. Activity 1I
A. Use the reaction velocities from the
time-course data to construct a
Michaelis-Menten plot
B. Use your plot to estimate Vmax and
KM for your enzyme
14. Is Group1avir a possible drug candidate against
HIV?
+ Group1avir
Using enzyme kinetics to evaluate drug candidates
Vmax = 96.4 μM
KM = 10.2 μM
-Group1avir
Vmax = 96.4 μM
KM = 47.0 μM
15. Trends in Annual Age-Adjusted* Rate of Death
Due to HIV Infection, United States, 1987−2009
Note: For comparison with data for 1999 and later years, data for 1987−1998 were modified to
account
for ICD-10 rules instead of ICD-9 rules.
*Standard: age distribution of 2000 US population
Saquinavir released onto
market by Roche
16. In the next lab session you will:
• Measure rates of an enzyme-
catalyzed reaction
• Use your data to construct a
Michaelis-Menten plot
• Determine values for Vmax and KM
17. Let’s remind ourselves what we’ve
accomplished
In this class you:
• Determined a reaction rate from experimental time-
course data
• Produced the Michaelis-Menten plot from experimental
data and estimate the kinetic parameters
• Used Michaelis-Menten plots to infer changes in
enzyme activity, e.g. in the context of a human disease
Editor's Notes
Use HIV-1 protease as a narrative framework. Briefly describe each of the steps of the HIV lifecycle and emphasize the role of HIV-1 protease.
Explain that we need to understand enzyme kinetics to begin to design a drug against this enzyme.
Recap briefly the general scheme of a enzyme catalyzed reaction.
Have the students shout out how the components of the HIV-1 protease reaction fit into this scheme. What is the enzyme? What is the substrate? Etc.
Point out that each point on the Michaelis-Menten plot corresponds to a reaction velocity determined from a time-course experiment. Walk them through Vmax and Km and be sure to explain how a low or high Km value impacts enzyme activity.
Split students into groups of two and have them use the data from the bottom of the worksheet to determine which of the time-course slopes corresponds to a substrate concentration of 25 micromolar.
Point out to students that the velocity is equal to dP/dT.
This activity should take about 2 mins.
Keep students in groups of two and have them use the data to construct a Michaelis-Menten plot. Point out that the [S] values for each time-course are now on the screen.
This activity should take ~ 5 mins to construct the graph and 2 mins to estimate Vmax and Km. Students need to be prompted to finish on time.
Clicker question to confirm that the students constructed their plots successfully.
Compare the students plots to the calculated one.
Tell them that we have developed a potential drug candidate against HIV-1 protease. We’re now going to use the effect of this drug on the kinetics of HIV-1 protease to evaluate if it’s a possible drug candidate.
Have the students discuss among themselves if the drug “group1avir” may act as an inhibitor of the protease. Use this as a lead in to the discussion of the mechanisms of enzyme inhibitors in the following lecture.
This activity should take ~2 mins to discuss and report back. Students should recognize that the KM increases and so the action of the enzyme has been impaired. This activity is a stepping stone to a broader discussion of what criteria is used to evaluate drug candidates.
Point out that a drug does not need to inactivate an target to be effective.
Potential discussion question. Why do we use drug cocktails for treatment rather than single drugs?
Use this slide to illustrate that the a drug with a similar mode of action i.e. competitive inhibition was released onto the market and had a huge impact on the rate of death from HIV infection. Provides extra context about the exercise and helps students develop higher order thinking.