michaelis menten...enzymes...

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param124
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michaelis menten...enzymes...

Post by param124 » Fri Sep 30, 2005 10:46 am

i have too question on this topic of michaelis menten equation...

1)why in the presence of a competitive inhibittor the value of Vmax is constant menawhile the Km(michaelis menten constant) does't change?

2)why in the presence of non-competitive inhibbitors the value of Vmax decreases and value of Km(michaelis menten constant) is a constant....

please do assist...some of the main topics for my exams....any help is very much appreciated

sdekivit
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Re: michaelis menten...enzymes...

Post by sdekivit » Sat Oct 01, 2005 5:55 pm

param124 wrote:i have too question on this topic of michaelis menten equation...

1)why in the presence of a competitive inhibittor the value of Vmax is constant menawhile the Km(michaelis menten constant) does't change?

2)why in the presence of non-competitive inhibbitors the value of Vmax decreases and value of Km(michaelis menten constant) is a constant....

please do assist...some of the main topics for my exams....any help is very much appreciated


first what is the Michaelis-Menten-constant? this is the rate constant of the dissociation reactions divided by the reaction rate constant of formatrionreaction of the enzyme-substrate-complex::

Km = k(dissociation) / k(formation)

what happens when a competitive inhibitor is added: the active site is blocked and thus the formationrate constant of the formation of the enzyme-substrate-complex decreases
thus: with a competitive inhibitor Km increases, but because the enzyme itself is not changed when we look at the conformation, the maximum speed of the reaction doesn't change.

What happens with a non-competitive inhibitor: In this case it's like we remove enzymes by making them inactive (conformation change) and thus Km stays the same, but the rate of the reaction catalyzed by this enzyme decreases (less enzymes)

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