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July 20, 2025, 01:31:52 pm

Author Topic: Competitive vs. non-competitive inhibition question  (Read 13553 times)  Share 

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Competitive vs. non-competitive inhibition question
« on: February 25, 2013, 06:06:40 pm »
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How could you distinguish between competitive and non-competitive inhibition in an isolated system?

From Biozone p35 Q6.(b)

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Re: Competitive vs. non-competitive inhibition question
« Reply #1 on: February 25, 2013, 10:17:39 pm »
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Okay, I don't own a copy of Biozone, but I'll do what I can (I assume we're talking about the inhibition of enzymes):

Competitive inhibition is when an inhibitor molecule directly blocks the active site of an enzyme, where the reaction with a substrate would normally occur. Because the active site is occupied by the inhibitor, the enzyme cannot perform its function, as shown below:


Non-competitive inhibition is when an inhibitor molecule attaches to the enzyme at a location other than the active site. This distorts the shape of the enzyme, and ultimately the shape of the active site is changed so it can no longer accommodate its substrate. Ergo, the enzyme cannot perform its intended function, as shown below:


Another difference is that competitive inhibition is often permanent, while non-competitive inhibition can sometimes be reversed.
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Snorlax

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Re: Competitive vs. non-competitive inhibition question
« Reply #2 on: February 28, 2013, 09:49:28 pm »
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How are inhibitors present to become a competitive inhibitor?
In my textbook it says "if a large amount of product is present in the cell, it will act as an inhibitor"
What 'products'? Are they the products of reactions...like glucose? So glucose could become an inhibitor if it was abundant in a cell?
*glucose is probably a very inaccurate example...but my point; what type of products?!
« Last Edit: February 28, 2013, 09:51:13 pm by nonsense »
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Re: Competitive vs. non-competitive inhibition question
« Reply #3 on: February 28, 2013, 09:52:31 pm »
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How are inhibitors present to become a competitive inhibitor?
In my textbook it says "if a large amount of product is present in the cell, it will act as an inhibitor"
What 'products'? Are they the products of reactions...like glucose? So glucose could become an inhibitor if it was abundant in a cell?

This is true, but 'inhibitors' can sort of be of two types.

1. Foreign, such as venoms and poisons

2. Local, which isn't strictly inhibition but more slowing of a rate of reaction. If there is more product than substrate in the cell, there is less for the enzyme to react with. At a point, the amount of product can be so large that it stops the function of the enzyme altogether.
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Jayward

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Re: Competitive vs. non-competitive inhibition question
« Reply #4 on: February 28, 2013, 09:55:36 pm »
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How are inhibitors present to become a competitive inhibitor?
In my textbook it says "if a large amount of product is present in the cell, it will act as an inhibitor"
What 'products'? Are they the products of reactions...like glucose? So glucose could become an inhibitor if it was abundant in a cell?
*glucose is probably a very inaccurate example...but my point; what type of products?!

This sounds like allosteric regulation. This is a special type of homeostatic regulation, when the products of a reaction exceed the requirement, the product acts as an enzyme inhibitor until product levels decrease. Not all products become inhibitors. this only occurs in a specific set of reactions. i dont even think that this is even part of the study design anymore, so dont stress too much.

PS: Glucose will NEVER act as an inhibitor to glucose 'acquisition processes'. its too precious, and cells want as much glucose as possible. :D
and what alondouek said about local inhibitors is also true. When their is too much oxygen in the air, photosynthesis decreases in speed due to the phenomenon that he mentioned. But as he said, that does not necessarily mean that theyre acting as inhibitors. there is a stark distinction between the two
« Last Edit: February 28, 2013, 09:59:53 pm by Jayward »

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Re: Competitive vs. non-competitive inhibition question
« Reply #5 on: February 28, 2013, 09:56:50 pm »
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This sounds like allosteric regulation. This is a special type of homeostatic regulation, when the products of a reaction exceed the requirement, the product acts as an enzyme inhibitor until product levels decrease.

i.e. Negative feedback, but you might not be there yet :P
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Re: Competitive vs. non-competitive inhibition question
« Reply #6 on: February 28, 2013, 10:13:43 pm »
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Listening to douchy at the moment to hear his explanation of this :)
Still not 100% on this yet.
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Re: Competitive vs. non-competitive inhibition question
« Reply #7 on: February 28, 2013, 10:21:59 pm »
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Damn, I wish I could explain this to you in person haha; I taught this to my class last year.

Maybe it might help for you to think of it as equilibrium?

Too much substrate enzyme compensates, makes more product.

Too much product enzyme can't do much, can get inhibited (active site blocked) by product. Another enzyme may be needed to break down the product back into substrate.
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Jayward

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Re: Competitive vs. non-competitive inhibition question
« Reply #8 on: February 28, 2013, 10:27:34 pm »
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watch these. first rate :D they both go a bit heavy though. Dont need to know some of the stuff they was saying, but if you do, youre a gun
« Last Edit: February 28, 2013, 10:31:58 pm by Jayward »

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Re: Competitive vs. non-competitive inhibition question
« Reply #9 on: February 28, 2013, 10:32:34 pm »
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Too much product enzyme can't do much, can get inhibited (active site blocked) by product. Another enzyme may be needed to break down the product back into substrate.
By the product it produced? (The reactions product)
Also, can a single enzyme (with multiple active sites) have a different role depending on the substrate that locks into the active site? Ughhhh, like can the multiple active sites be different, thus have different jobs depending on which substrate binds into the active site?
« Last Edit: February 28, 2013, 10:34:49 pm by nonsense »
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Re: Competitive vs. non-competitive inhibition question
« Reply #10 on: February 28, 2013, 10:35:05 pm »
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By the product it produced?
Also, can a single enzyme (with multiple active sites) have a different role depending on the substrate that locks into the active site? Ughhhh, like can the multiple active sites be different, thus have different jobs depending on which substrate binds into the active site?

Yep, by the product it produced!

I haven't ever heard of an enzyme having more than one active site, but specificity would tell us that it would still carry out the same function at each active site, which would have to be structurally identical.
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Re: Competitive vs. non-competitive inhibition question
« Reply #11 on: February 28, 2013, 10:54:15 pm »
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Yep, by the product it produced!

I haven't ever heard of an enzyme having more than one active site, but specificity would tell us that it would still carry out the same function at each active site, which would have to be structurally identical.
Ahh thanks, I think I'v got a grasp on it...
They're definatley enzymes with multiple active sites. - I think-pretty certain :)
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Re: Competitive vs. non-competitive inhibition question
« Reply #12 on: February 28, 2013, 11:00:04 pm »
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watch these. first rate :D they both go a bit heavy though. Dont need to know some of the stuff they was saying, but if you do, youre a gun
Yeah thanks for that, but allosteric enzymes-we/I call it non-competitive inhibition. Haha
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