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hk213

effect of substrate concentration on enzyme activity

okay, i posted something like this a few weeks ago and this time, i actually finished the experiment.

The lab had to do with the effect of sustrate concentration(hydrogen peroxide) on enzyme activity.

In my case, the substrate was h2o2 and the enzyme was fresh liver which was blended. -> you can see the enzyme activity by testing the amount of oxygen produced.

Here is the problem though...

i predicted that the amount of oxygen produced will increase as the substrate concentration increase, but it turned out that the highest amount of oxygen was produced

when the substrate concentration(h2o2) was around 7.5%.

My concentrations were 30% , 15%, 7.5%, 3% and 0%

Can anyone explain why this happened????

p.s) i conducted this 3 times for each concentration

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Hydrogen peroxide is acidic, therefore at high concentrations, denaturation occurred.

Thanks a lot you are so good

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You maxed out your enzyme concentration. Concentrations can increase the rate and amount of the O2 produced but eventually the enzymes can't work any faster no matter how much enzyme you put in. It's like cars and tunnels. No matter how many cars you try to shove through that tunnel, only so many can get through in x amount of time.

I'm assuming you controlled the amount of time that you let the reaction occur by the way :yes:

If the h2o2 was that acidic denaturing would have caused MUCH less O2 to be produced, not max it...

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Vernier is a company that creates tons of probes used for labs. They have O2 detectors, CO2 detectors, motion sensors, pH probes, conductivity probes, force plates, temperature probes, all kinds of stuff. The LabQuest is a handheld device that will collect the data using the probes and then display it as a graph/chart for you. LoggerPro will do the same thing but it's a computer program, not handheld.

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Vernier is a company that creates tons of probes used for labs. They have O2 detectors, CO2 detectors, motion sensors, pH probes, conductivity probes, force plates, temperature probes, all kinds of stuff. The LabQuest is a handheld device that will collect the data using the probes and then display it as a graph/chart for you. LoggerPro will do the same thing but it's a computer program, not handheld.

Thanks a lot!

Would the oxygen be measured straight from the solution? I'm not sure if my school has LabQuest O2 detector . But at least I could mention it in my design... If we'll have to execute the practicals I'm don't have a good way to collect data if I don't know how to use the O2 detector :'D

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The O2 detector is a container and then measures the amount in the container. Pretty sure it measures it by measuring the area around the probe and then calculating the amount for the known volume (the container has a set volume) and gives you a number. Or something like that. So no, the O2 can't be measured right out of the solution, however the O2 will eventually surface by bubbling through the solution and this be in the air inside the container when the vapor pressure reaches it's equilibrium.

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