Cleland Diagram & Binding Order from Lineweaver Burke Plots

In summary, the conversation discusses the mechanism of a trisubstrate reaction, specifically focusing on parts (b) and (d). The first pair of graphs show a sequential reaction when Cysteine is saturated, while the others show a ping-pong reaction with parallel slopes. It is mentioned that sequential reactions involve reactants binding, such as ATP and GlcN, followed by a reaction and then Cysteine binding to react with an intermediate. However, it is unclear if this makes sense if Cysteine is already saturated. The question of how we know ATP binds first in part (d) is raised, as well as the confusion surrounding part (e) where ATP, with the highest K_m and lowest binding
  • #1
The Head
144
2
Homework Statement
(b) Draw a Cleland diagram for the mechanism of the reaction shown above that is consistent with the following data. Briefly justify your reasoning.

(d) In light of the data in parts (b) and (c), can you conclude that ATP binds first to the enzyme? Briefly explain your reasoning.

(e) Kinetic data give the following KM values for the three substrates:
ATP KM = 1.8 mM Cys KM = 0.1 mM GlcN KM = 0.2 mM
At steady-state inside the cell, the enzyme is entirely saturated with ATP. How would you rationalize this fact in light of the above KM data?
Relevant Equations
N/A
I am mostly focused on parts (b) and (d), which I typed out. For (b), I can tell the first pair of graphs is a sequential reaction (when Cysteine is saturated), but it appears ping-pong for the others because the slopes are roughly parallel. I know sequential has to reactants binding (so I guess that would be ATP and GlcN), and I suppose that a reaction occurs there and then maybe Cysteine binds to react with an intermediate?

But then again, if Cysteine is saturated, I don't know if that makes sense, because Cysteine should be able to bind.

Also, how do we know ATP binds first (part d)? Part (e) also confuses me, because ATP has the highest K_m, so the lowest binding affinity, but ATP is saturating the enzyme. It seems like there would be less binding for that.
 

Attachments

  • Screen Shot 2022-02-14 at 7.11.23 PM.png
    Screen Shot 2022-02-14 at 7.11.23 PM.png
    29.3 KB · Views: 173
  • Screen Shot 2022-02-14 at 7.11.37 PM.png
    Screen Shot 2022-02-14 at 7.11.37 PM.png
    27.9 KB · Views: 159
  • Screen Shot 2022-02-14 at 7.11.49 PM.png
    Screen Shot 2022-02-14 at 7.11.49 PM.png
    23.3 KB · Views: 154
  • Screen Shot 2022-02-14 at 7.11.58 PM.png
    Screen Shot 2022-02-14 at 7.11.58 PM.png
    12.2 KB · Views: 163
Physics news on Phys.org

FAQ: Cleland Diagram & Binding Order from Lineweaver Burke Plots

What is a Cleland Diagram?

A Cleland diagram is a graphical representation of enzyme kinetics, specifically the relationship between substrate concentration and reaction rate. It shows the different kinetic patterns that can occur, such as competitive, non-competitive, and uncompetitive inhibition.

What is a Lineweaver Burke Plot?

A Lineweaver Burke plot is a graphical representation of enzyme kinetics, specifically the relationship between reaction rate and substrate concentration. It is a double reciprocal plot that allows for the determination of important kinetic parameters, such as the Michaelis-Menten constant and maximum reaction rate.

How are Cleland Diagrams and Lineweaver Burke Plots related?

Cleland diagrams and Lineweaver Burke plots are both graphical representations of enzyme kinetics. They are related in that they both show the relationship between substrate concentration and reaction rate, but they differ in the type of information they provide. Cleland diagrams show the different kinetic patterns that can occur, while Lineweaver Burke plots allow for the determination of kinetic parameters.

What is binding order in Lineweaver Burke plots?

Binding order in Lineweaver Burke plots refers to the order in which substrates and inhibitors bind to the enzyme. This can be determined by examining the slope of the lines on the plot. A steeper slope indicates a higher binding order, while a flatter slope indicates a lower binding order.

Why are Cleland Diagrams and Lineweaver Burke Plots important in enzyme kinetics?

Cleland diagrams and Lineweaver Burke plots are important tools in enzyme kinetics because they allow for the determination of important kinetic parameters, such as the Michaelis-Menten constant and maximum reaction rate. They also provide a visual representation of the relationship between substrate concentration and reaction rate, making it easier to analyze and interpret enzyme kinetics data.

Similar threads

Kinetics Assignment - Reaction Orders
Replies
1
Views
2K

Hot Threads

Recent Insights

Back
Top