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Homework Help: Stoichiometry with enzymes and temperature

  1. May 30, 2012 #1
    I'm currently doing an EEI with catalase and hydrogen peroxide. I'm just wondering about the effects of increasing the temperature of the catalase and h2o2. For example, if I get 50mL of oxygen produced when both are at 40°C and the reaction occurs for 8 seconds. If I decrease the temperature to 30°C, 20°C and 10°C what should I expect to happen with the time and amount of oxygen produced? The same goes for if I increase it to 50°C and 60°C. Should the amount of oxygen being produced form a parabolic relationship, peaking at 40°C, or will there simply be no oxygen produced at certain temperatures?

    Temperature is one of our three variables being tested, the other two being the concentration of h2o2 and catalase.

    I have calculated the theoretical yield and our actual yields are very close. I was not able to calculate the time the reaction should occur for with the catalase concentrations increasing however I would like to have some calculations for the temperatures. Thanks.
  2. jcsd
  3. May 31, 2012 #2


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    We really have to guess what you mean. E.g. by theoretical yield. I guess you mean the moles of O2 produced were half the number of moles of H2O2you put there. ?

    I don't know what an EEI is and I don't know how youB are doing the experiments. It sounds like you are measuring the volume of O2 produced after 8 sec varying the other factors. ?

    I don't like hearing of 'time of reaction' for an enzyme or any other reaction. RATES of reaction are the only thing that means anything. If you assume the rate is constant then you might hope you are estimating a rate from what you call the time of reaction (again guessing what you are really doing).

    I would not bother to do calculations with experients as crude as these sound. They sound intended to give qualitative results only.

    As a rule rates of reactions increase with temperature. But at higher temperatures the enzyme catalyst may be inactivated (denatured). If this happens at 60 deg within your 'reaction time' then you may see your 'reaction time' increase or the reaction not be' completed at the higher temperature/s. It doesn't mean anything to try and fit to a parabola or anything else.
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