Lineweaver-Burk Plot Explained
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Today we will look at
Today we will look at the Lineweaver-Burk plot, which is central in enzyme kintetics. A typical curve of enzyme kinetics plots the velocity or rate of reaction on the y-axis and the substrate concentration on the x-axis. The rate of reaction increases with the substrate concentration but the growth is logarithmic, meaning that it starts plateauing like this. The maximum velocity of the reaction or Vmax is therefore only theoretical since the reaction never truly plateaus in this manner. Therefore we get an error in both our Vmax as well as Km.
To solve this, we can use a Lineweaver-Burk plot, but do not worry about this quite yet. First, recall the Michaelis-Menten equation v = Vmax times [S] divided by Km + [S] where v is the rate of reaction, Vmax is the theoretical maximum possible rate of the reaction, S is the concentration of substrate and Km is the Michaelis constant. If this equation is inversed we get 1 over V = Km + [S] over Vmax times [S]. This can be modified so that we instead get 1 over V = Km over Vmax times [S] + 1 over Vmax.
Now let’s compare this new equation to the general equation of a straight line: Y = mx + c, where m is the gradient or steepness of the line and c is the y-intercept. We can match the components of the new equation to those of the general equation of a straight line. In other words, 1 over V will be the Y part, Km over Vmax will be the m part, 1 over [S] will be the x part and 1 over Vmax will be the c part.
Let’s take another look at the Lineweaver-Burk plot with that in mind. Take a quick moment and pause the video to see if you can fill in these components in the proper places. Ok here we go:
- 1 over V is the y-axis
- Km over Vmax is the gradient of the slope
- 1 over [S] is the x-axis, 1 over Vmax is the y-intercept
- -1 over Km is the x-intercept and
Due to it being a straight line graph the estimate of Vmax becomes easy since we can just look at where the y-intercept occurs to get the value for 1/Vmax. Furthermore any change in the value of Vmax or Km can easily be spotted from the graph. As a result this graph is one of the most useful ones for understanding enzyme inhibition.
If you want to understand the Lineweaver-Burk plot as it relates to Enzyme inhibition, check out this video! UNTIL NEXT TIME!
To solve this, we can use a Lineweaver-Burk plot, but do not worry about this quite yet. First, recall the Michaelis-Menten equation v = Vmax times [S] divided by Km + [S] where v is the rate of reaction, Vmax is the theoretical maximum possible rate of the reaction, S is the concentration of substrate and Km is the Michaelis constant. If this equation is inversed we get 1 over V = Km + [S] over Vmax times [S]. This can be modified so that we instead get 1 over V = Km over Vmax times [S] + 1 over Vmax.
Now let’s compare this new equation to the general equation of a straight line: Y = mx + c, where m is the gradient or steepness of the line and c is the y-intercept. We can match the components of the new equation to those of the general equation of a straight line. In other words, 1 over V will be the Y part, Km over Vmax will be the m part, 1 over [S] will be the x part and 1 over Vmax will be the c part.
Let’s take another look at the Lineweaver-Burk plot with that in mind. Take a quick moment and pause the video to see if you can fill in these components in the proper places. Ok here we go:
- 1 over V is the y-axis
- Km over Vmax is the gradient of the slope
- 1 over [S] is the x-axis, 1 over Vmax is the y-intercept
- -1 over Km is the x-intercept and
Due to it being a straight line graph the estimate of Vmax becomes easy since we can just look at where the y-intercept occurs to get the value for 1/Vmax. Furthermore any change in the value of Vmax or Km can easily be spotted from the graph. As a result this graph is one of the most useful ones for understanding enzyme inhibition.
If you want to understand the Lineweaver-Burk plot as it relates to Enzyme inhibition, check out this video! UNTIL NEXT TIME!
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