Lineweaver-Burke

[MedPR]

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http://forums.studentdoctor.net/showpost.php?p=2887133&postcount=8


According to that link, the slope of the line increases for non-competitive inhibition. I thought it would decrease as you add more inhibitor?

I understand that in competitive inhibition, the slope increases because the x-intercept moves towards 0 (Km increases) but the y-intercept stays the same (Vmax doesn't change).

In noncompetitive, the slope decreases because the x-intercept stays the same (Km) but the y-intercept decreases (Vmax decreases as you add more inhibitor).

Which one is right?

 

[Ssina]

I think that post is talking about the graph with x axis being 1/-Km and as you mentioned Km gets bigger for competitive inhibitor so the fraction of -1/Km gets smaller, as the result the slop increases

 

[MT Headed]

The Y axis is a plot of 1/Vmax so as Vmax goes down, the Y intercept goes up. Which makes the slope steeper.

 

[chiddler]

Nevermind.

 

[MedPR]

The Y axis is a plot of 1/Vmax so as Vmax goes down, the Y intercept goes up. Which makes the slope steeper.

Ah that's right, I forgot the y axis was 1/Vmax and not Vmax. Thanks.

So both slopes increase as either type of inhibitor increases in concentration. Competitive because Km goes down (x-intercept approaches 0, 1/KM increases) and Noncompetitive because Vmax goes down (y-intercept approaches infinity, 1/Vmax increases).