[carosoares]

HI! I'm an IB student in my senior year, and the program requires us to write an IA, which is basically a fancy lab report. For mine, I chose to look at the decomposition of hydrogen peroxide using KI and catalase from liver. I measured the pressure using the Vernier interface changing the temperature to later find the activation energy from the catalyst and the enzyme, and thus compare them at the end. However, I cannot measure the concentration of catalase (or molarity) because I have no idea of how much catalase there is in chicken liver, and I would need that in order to find the rate constant (k) and then the activation energy... right?
What do I do? My lab is due in less than a week and I am stuck in my processed data! Does anyone know the amount of catalase in chicken liver? Or how can I measure the activation energy, (using the pressure (kPa) recorded at different temperatures), without knowing the concentration of catalase in liver? (I used 1ml of liver per 9ml of water btw).
Thank you sososososo much!!

[Borek]

Activation energy could be determined by doing otherwise identical decomposition experiments in two different temperatures.

Concentration has to be determined by some other method.

[Babcock_Hall]

It is difficult to do this topic justice in the form of comments at a discussion board.  However, obtaining a molar concentration of an enzyme is not a straightforward problem, owing to at least two factors.  One is that it is often a very small number, sometimes in the nano molar range.  A second factor is that there are many other proteins around, unless one is working with purified catalase.  This makes me suspect that there must be a work-around.