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Postby Tiamaria » Fri Jan 14, 2011 5:42 pm

Q: you are observing an enzyme driven reaction. You add a chemical that inhibits the reaction. You suspect that you have added a competitive inhibitor. What 2 pieces of evidence lead you to this conclusion.

This is what I was thinking: because a competitive inhibitor is reversible, does that mean you can see the rxn undo. I dont quite understand what reversible means. For example if if you drop red food coloring into water you see it diffuse and become pink water. When i think of the word reversible i'd think that the water would "undo" that mix and then you'd see the clear water and the food coloring seperate. but i know that doesnt happen, so what exactly does reversible reaction mean. I was thinking that if i am observing a reaction, that doesnt mean that i can see where my chemical binds to right? that would be so microscopic, and i know that competitve inhibitors bind to the active site, but i dont feel that that is the correct answer because how could you see that? I'm taking an online class and I need some guidance with this one!

Thank you
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Postby kolean » Sat Jan 15, 2011 3:38 pm

When looking at an enzyme reaction, you will want to look at how much reaction chemicals are being used, and how much of the product is being made. Suppose the reaction makes carbon dioxide - the product would be perhaps bubbles in the solution. If a competitive inhibitor was added in certain amounts to the solution containing the same amounts of reacting chemicals and enzyme, and with each increasing amount of inhibitor added, less and less bubbles were being made. This could be evidence that it is a competitive inhibitor.
So, by looking at the product, how could you find more evidence that it is a reversible reaction?
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Postby Darby » Sat Jan 15, 2011 9:05 pm

Are you supposed to somehow differentiate between a competitive and a noncompetitive inhibitor?
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Postby JackBean » Sat Jan 15, 2011 10:23 pm

You should be able to understand, what inhibitor is, in the first place ;)
Then you should easily understand, what means competitive inhibitor.
You can differentiate them by more ways then only looking on the structure :) Just measure the kinetics and see what happens. Even whether are you able to override the inhibitor effect by addition of more substrate ;)

Cis or trans? That's what matters.
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