How Does an Inhibitor Affect Enzyme Kinetics?

[leopard]

I'm asked to calculate V_max and K_M from this, with and without the inhibior, and answer what kind of inhibitor it is.

I have plotted 1/ vs 1/V₀ here:

The x-intercept is -1/K_M. The value I get is -1/K_M=-4E4, so that K_M=25E-6. Does this mean that K_M=25E-6 M? My book says 20-24 M. Of course, I might have been unaccurate in drawing the graph, but why do I miss by a factor of 1E6?

 

[epenguin]

Maybe the book says (20-24)uM (micromolar)?

But at your level I have some news for you, part bad part good.

The bad news is sometimes books are wrong. Contain slips. Misprints. That the author does not pick up - can be quite hard to see when you read you own thing.

The good news is you are sometimes right.

 

[leopard]

Am I right this time?

 

[epenguin]

Looks right to me. Of course I could be wrong.

What is your answer to the other part of the question, type of inhibitor?

 

[leopard]

Noncompetitive.

 

[epenguin]

Noncompetitive.

Right