enzyme inhibition and Vmax

[KVS]

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My question is, how do non-competitive inhibitors affect Vmax?

I know that Vmax is affected by enzyme concentration and enzyme TYPE.

Since most of the enzyme kinetics graph have a constant enzyme concentration, does the enzyme TYPE become changed due to to allosteric binding?
Also,WHY doesn't increasing substrate concentration overcome this to restore Vmax?

Thanks!😕

 

[AFLATPEG]

My question is, how do non-competitive inhibitors affect Vmax?

I know that Vmax is affected by enzyme concentration and enzyme TYPE.

Since most of the enzyme kinetics graph have a constant enzyme concentration, does the enzyme TYPE become changed due to to allosteric binding?
Also,WHY doesn't increasing substrate concentration overcome this to restore Vmax?

Thanks!😕

Non-competitive inhibitors bind to a different site so adding more substrates wouldn't help, thus the Vmax is lowered but Km stays the same. In contrast, a competitive inhibitor is competing for the SAME SITE so adding more substrates would help overcome it but slowly so the Km is higher but the Vmax is still the same because it'll eventually get there.

What helps me is looking at the graphs and talking yourself through it- it makes sense!

 

[Francium87]

My question is, how do non-competitive inhibitors affect Vmax?

I know that Vmax is affected by enzyme concentration and enzyme TYPE.

Since most of the enzyme kinetics graph have a constant enzyme concentration, does the enzyme TYPE become changed due to to allosteric binding?
Also,WHY doesn't increasing substrate concentration overcome this to restore Vmax?

Thanks!😕

non comp. inhibition is when an inhibitor binds allosterically, see the binding of the inhibitor doesn't affect the binding affinity of the substrate to the enzyme ...the substrate binds fine however, the changing in the morphology of the Enzyme+Sub complex to Enzyme + product can't be achieve...so if you have 10 enzymes and 2 of them are defective due to an inhibitor then you got 8 left that no matter how much you increase sub. concentration you would still get the product of the 8 enzymes

Comp. inhibition, you're competing for the same active site so obviously, two things going for one decreases the binding affinity of the substrate to the active site...so what we do is
increase the concentration of the substrate 10000000000 : 1 to overcome the comp. inhibitor concentration

 

[Gauss44]

Non-competitive inhibitors bind to a different site so adding more substrates wouldn't help, thus the Vmax is lowered but Km stays the same. In contrast, a competitive inhibitor is competing for the SAME SITE so adding more substrates would help overcome it but slowly so the Km is higher but the Vmax is still the same because it'll eventually get there.

What helps me is looking at the graphs and talking yourself through it- it makes sense!

Correct.

Chad also explains this very well. Go here: http://www.fatwallet.com/forums/free-stuff/1247592/ Scroll down to Chad and Alan's MCAT Videos, click on the link, then scroll down again to the free video called, "Enzymes."

(Direct links weren't working.)
www.***********.com/videos/MCAT

http://www.***********.com/videos/MCAT/