Recommended acid / base concentrations in a hydrogen peroxide vs. catalase practical

[Stevie D]

Hello folks,

 

As I think I mentioned in a previous post, I'm doing some science teaching at a local college.

 

To achieve the unit descriptor for the module the students are working on, they need to, and I quote: "Investigate and explain the effects of one

or more given factors, for example temperature, pH, substrate concentration or enzyme concentration on the functioning of enzymes."

Should be easy enough. I want to run this practical, taken from the Nuffield Foundation website. That will hit the criterion for showing the effect of concentration on an enzyme-substrate based reaction. I will adapt the method to include a heated water bath to bring temperature into the equation in a separate practical run in the same session.

However, for pH I'm not sure what to do. It would make life easy to use the above method, without the water bath or fluctuations in substrate-enzyme concentration and merely add acids / bases at a variety of pH values. In this similar method from the same website, it recommends sodium hydroxide at 0.25M. Do you think that will have a significant effect on a reaction involving 2cm³ of 10-30vol hydrogen peroxide vs. 20cm³ of (catalase containing) potato puree? If so, what volumes of bases (and acids) do you think I should use at these concentrations?

Thanks for your time,

Steve

Edited February 26, 2014 by Stevie D