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competitive and non-competitive inhibition of enzymes

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competitive and non-competitive inhibition of enzymes

Postby Question » Thu Mar 09, 2006 3:13 pm

Ok, what i don`t get with this is the graph that show the differences between the two sorts of inhibition. With the competitive inhibitor it slows down the rate of reaction but if the substrate concentration is increased the rate of reation increases up to almost normal levels.

With non-competive inhibition the inhibitor slows down the rate of reaction, in this case the plateau for the rate of reaction is markedly lower if the substrate concentration is increased.

What i have difficulty in understanding is the explanation of what the inhibiors do to the enzymes, with competitive inhibition the inhibitor compets with the substrate for the active site, according to the textbook if it is successful it becomes jammed, this would effectively permenantly break the enzyme then, stop it from working?

In the case of the non-competive inhibitor the inhibitor binds to another part of the enzyme molecule apart from the active site, altering the shape of the active site so it cannot bond with the substrate, or altering it chemically so it can no longer react with the substrate.

So why are the graphs so different? In both cases the enzyme if they come into contact with the inhibitor will be effectively broken, so the graphs should be similar.

I don`t think the explanation i have read for what is takinbg place is adequate, can anyone enlighten me please?
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Postby canalon » Thu Mar 09, 2006 5:04 pm

better explained than I will ever be able to here:

http://en.wikipedia.org/wiki/Competitive_inhibition
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competitive and non-competitive inhibitor

Postby sham » Fri Mar 10, 2006 4:02 am

There are generally 2 types of inhibitors; reversible and non-reversible inhibitors. Competitive and non-conpetitve inhibitors are generally grouped under reversible inhibitors. Meaning, once the inhibitors left the enzymes, the enzymes can function again.
Non-reversible inhibitors are usually heavy metals where they will occupy any site of the enzyme and disable it permanently.
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Re: competitive and non-competitive inhibition of enzymes

Postby kiekyon » Fri Mar 10, 2006 7:37 am

Question wrote:In both cases the enzyme if they come into contact with the inhibitor will be effectively broken, so the graphs should be similar.



nope, both competitive and non-competitive inhibition are reversible
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