Graphing the Results from Kinetics Experiments with Enzyme Inhibitors

In summary, graphing the results from kinetics experiments with enzyme inhibitors serves to visually represent the relationship between enzyme activity and inhibitor concentration. A common type of graph used for this purpose is a double-reciprocal or Lineweaver-Burk plot, which can help determine the type and mechanism of inhibition. The rate of reaction can be calculated by finding the slope of the line on the graph. The graph provides information about the inhibitor's effectiveness, type of inhibition, mechanism of action, and rate of reaction at different concentrations. It can also guide the design of more potent and safer inhibitors by identifying optimal concentration and potential interactions.
  • #1
Sara1bara
1
0

Homework Statement


The following kinetic data were obtained for an enzyme in the absence of any inhibitor (1), and in the presence of two different inhibitors (2) and (3) at 5mM concentration. Assume [ET] is the same in each experiment[/B]
(1) (2) (3)
v (umol/mL * sec) v (umol/mL * sec) v (umol/mL * sec)
(mM)
1 12 4.3 5.5
2 20 8 9

4 29 14 13
8 35 21 16
12 40 26 18


Graph these data as Lineweaver-Burk plots and use your graph to find answers to a and b

a. Determine Vmax & Km for the enzyme
b. Determine the type of inhibition and the KI for each inhibitor

Homework Equations



1/Vmax = y-intercept, slope = km/Vmax

The Attempt at a Solution


See attached table*[/B]
This is a table of above plus the reciprocal of each one. It is from the answer key of the homework, however for 1/ instead of the answer being 1, they change the units to M^-1. Similarly for V the units are mL*sec/umol and 1/V the units are mL*sec/umol. I do not know why they change the units and it confuses me on how to get all of the numbers.

From there, I made a graph, one for each of the inhibitors. X was the 1/ value and Y was the 1/V value.

From there, I was unsure how to find the slope and y-intercept since the numbers are not clear cut. I used the formula 1/V = Km/Vmax X 1/ + 1/Vmax to understand the relationship between y-intercept and slope. The answer key explained the formulas for each of the inhibitors making it possible for me to understand how to calculate Vmax and Km by knowing that 1/Vmax was the y-intercept and that the slope was Km/Vmax.

The answer key showed these equations:

1. 1/V = 63.1 (1/[S}) + 1.96 X 10^4
2. 1/V = 212.3 (1/) + 1.99 X 10 ^4
3. 1/V = 137.4 (1/) + 4.38 X 10^4

From here I calculated the Km and Vmax, but again was confused with units.
I also tried calculating the slope via the equation y2-y1/x2-x1 using two points, but was off compared to the answer key.

For part b. I worked with my knowledge of the different types of inhibitors to know which formula to use

Competitive : Km,app = Km(1 + I/KI)
Noncompetitive: 1/Vmax,app = 1/Vmax (1 + I/KI)

It was hard for me to know which numbers to plug in here as part a and the introduction to the problem were also confusing.

Thank you in advance for any help you can give!
 

Attachments

  • Screen Shot 2014-11-15 at 7.01.11 PM.png
    Screen Shot 2014-11-15 at 7.01.11 PM.png
    9.7 KB · Views: 747
Physics news on Phys.org
  • #2
I am sorry, but your post is so badly formatted I can't follow it. I even tried to clean the formatting up, but it just doesn't work.

Part of the problem stems from the fact [S] is not only a concentration of specie S, but also a formatting tag that starts a strikeout text. But you have also formatted indices using nested text size directive, and bold tags are added on top of that, making it a complete mess. Sorry, I gave up. Please contact me privately and we will try to do something about the text.
 

FAQ: Graphing the Results from Kinetics Experiments with Enzyme Inhibitors

1. What is the purpose of graphing the results from kinetics experiments with enzyme inhibitors?

The purpose of graphing the results from kinetics experiments with enzyme inhibitors is to visually represent the relationship between enzyme activity and inhibitor concentration. This allows for a better understanding of the effectiveness of the inhibitor and its mechanism of action.

2. What type of graph is typically used for this type of experiment?

A common type of graph used for kinetics experiments with enzyme inhibitors is a double-reciprocal or Lineweaver-Burk plot. This plot helps to determine the type of inhibition (competitive, non-competitive, or uncompetitive) by analyzing the intersecting lines on the graph.

3. How do you calculate the rate of reaction from the graph?

The rate of reaction can be determined by calculating the slope of the line on the graph. This can be done by finding the change in y-values (enzyme activity) divided by the change in x-values (inhibitor concentration) between two points on the line.

4. What information can be gathered from the graph?

The graph can provide information about the effectiveness of the inhibitor, such as the concentration needed to achieve a certain level of inhibition. It can also show the type of inhibition and the mechanism of action, as well as the rate of reaction at different inhibitor concentrations.

5. How can the graph be used to improve enzyme inhibitor design?

By analyzing the graph, researchers can determine the optimal inhibitor concentration for the desired level of inhibition. They can also use the information to design more potent inhibitors or modify existing ones to improve their effectiveness. Additionally, the graph can help identify any potential side effects or interactions with other compounds, aiding in the development of safer and more effective enzyme inhibitors.

Back
Top