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Biology Enzyme Investigation: Experiment to Determine whether Copper Sulphate Solutio

Experiment to Determine whether Copper Sulphate Solution Inhibits the Breakdown of Hydrogen Peroxide by an the enzyme Catalase.

I need to know what is the control.

I have figured out so far if I calculate the rate of reaction without the copper sulphate solution understand certain conditions. Then calculate rate with copper sulphate solution showing its an inhibitor.

Determine type by adding more enzyme and work out rate.

Somebody please help!
Reply 1
supreme
Experiment to Determine whether Copper Sulphate Solution Inhibits the Breakdown of Hydrogen Peroxide by an the enzyme Catalase.

I need to know what is the control.

I have figured out so far if I calculate the rate of reaction without the copper sulphate solution understand certain conditions. Then calculate rate with copper sulphate solution showing its an inhibitor.

Determine type by adding more enzyme and work out rate.

Somebody please help!

The controlled variable? Or the control experiment?
The controlled variables will be a whole load of things - temperature, humidity, concentration etc, anything you are not chnaging or measuring.
The control will be the experiment without any copper sulphate solution, as it shows that there is no other factor affecting the experiment.
Reply 2
Enzyme kinetics can be generally be modelled by the Michaelis equation. This shows how the rate of reaction is related to the inital enzyme concentration (which is constant) and the substrate concentration at any one time:

r = (Vmax )/( + Km)

If one plots a graph of against rate (r), Vmax is the maximum rate reached, and Km (the "Michaelis constant) is the value of when the rate is exactly half Vmax.

Rearrangement of the Michaelis equation will allow you to determine the effect of an inhibitor and the type of inhibitor on an enzyme controlled reaction. By rewriting the equation in the form

1/r = 1/Vmax + Km/(Vmax )

Plot a graph of 1/ against 1/r: a so-called "Lineweaver-Burk plot". This will ought to give you a straight-line graph with gradient Km/Vmax, and a y-intercept of 1/Vmax. Plot a graph such as this for your control reaction, and then for your reaction with the copper (II) inhibitor.

If the inhibitor is competitive (unlikely in this case), Vmax is still reached, but a higher is required to outcompete the inhibitor, so Km is greater. The result is a similar graph of the same y-intercept, but a steeper slope.

If the inhibitor is uncompetitive, Vmax is NOT reached, and Km should remain unaffected. The result is a similar graph as the control, where the gradient is unchanged but the y-intercept is higher.

If the inhibitor is "mixed", then both the gradient and the y-intercept will be greater.

This method of Lineweaver-Burk plots should help you determine the effect of the inhibitor and the extent of this effect.
Reply 3
skevvybritt
The controlled variable? Or the control experiment?
The controlled variables will be a whole load of things - temperature, humidity, concentration etc, anything you are not chnaging or measuring.
The control will be the experiment without any copper sulphate solution, as it shows that there is no other factor affecting the experiment.


Thank you :smile:
Reply 4
belu_bustu
Enzyme kinetics can be generally be modelled by the Michaelis equation. This shows how the rate of reaction is related to the inital enzyme concentration (which is constant) and the substrate concentration at any one time:

r = (Vmax )/( + Km)

If one plots a graph of against rate (r), Vmax is the maximum rate reached, and Km (the "Michaelis constant) is the value of when the rate is exactly half Vmax.

Rearrangement of the Michaelis equation will allow you to determine the effect of an inhibitor and the type of inhibitor on an enzyme controlled reaction. By rewriting the equation in the form

1/r = 1/Vmax + Km/(Vmax )

Plot a graph of 1/ against 1/r: a so-called "Lineweaver-Burk plot". This will ought to give you a straight-line graph with gradient Km/Vmax, and a y-intercept of 1/Vmax. Plot a graph such as this for your control reaction, and then for your reaction with the copper (II) inhibitor.

If the inhibitor is competitive (unlikely in this case), Vmax is still reached, but a higher is required to outcompete the inhibitor, so Km is greater. The result is a similar graph of the same y-intercept, but a steeper slope.

If the inhibitor is uncompetitive, Vmax is NOT reached, and Km should remain unaffected. The result is a similar graph as the control, where the gradient is unchanged but the y-intercept is higher.

If the inhibitor is "mixed", then both the gradient and the y-intercept will be greater.

This method of Lineweaver-Burk plots should help you determine the effect of the inhibitor and the extent of this effect.


THANK YOU THANK YOU THANK YOU I really appreciate the extra information, that must have taken ages to type! :biggrin: