31 - iced

[ArchivalUser]

Which of the following will be unchanged in a Lineweaver-Burk plot of an enzyme with and without a competitive
inhibitor?


A. Km

B. Slope

C. x-intercept

D. y-intercept

[ArchivalUser]

ddddd

[ArchivalUser]

D?--V-max

[ArchivalUser]

dddd

[ArchivalUser]

....very good gals and guys....The correct answer is D. It is worth taking the time to learn how to read a Lineweaver-Burk plot.
Lineweaver-Burk plots are used to determine the Vmax and Km of an enzyme; they are also used to
differentiate between competitive and noncompetitive inhibition.

Note that in a Lineweaver-Burk plot, the slope is Km/Vmax, the x-intercept is -1/Km, and the y-intercept is
1/Vmax. In the presence of a competitive inhibitor, the Km(choice A) and therefore the slope (choice B) are
both increased. Similarly, if Km is increased, -1/Km will become less negative and the x-intercept will shift to the
right. Intuitively, this makes sense since a competitive inhibitor will increase the amount of substrate needed to
reach half-maximal velocity (definition of Km). In contrast, the Vmax, and hence the y-intercept, is unchanged
(choice D).

[ArchivalUser]

Thanks for a great review, iced!