Question

Why is a V vs S plot often inadequate for determining enzyme kinetic constants, and how do various alternate plotting methods allow these values to be determined more adequately? Give examples of alternate methods of kinetic analysis and their utility.

Answer 1

V vs [S] is graph is either sigmoidal or hyperbola for most of the enzymes.

From this kind of graphs, we can not clearly determine Vmax and Km as the graph is not a linear plot.

To solve this problem, various methods have plots have been developed.
1. The Lineweaver–Burk plot:
1/V on Y-axis and 1/[S] on X-axis
Y intercept = Vmax
X intercept = Km

2. Eadie–Hofstee plot
V on X-axis and V/[S] on X-axis
Y intercept = Vmax
X intercept = Km