What does the Y-intercept of a Lineweaver-Burk plot represent?

The Y-intercept of a Lineweaver-Burk plot, which is a double reciprocal plot used in enzyme kinetics, represents 1/Vmax. This plot is derived from the Michaelis-Menten equation, which describes the rate of enzymatic reactions.

In a Lineweaver-Burk plot, the x-axis represents 1/[S] (the inverse of the substrate concentration), and the y-axis represents 1/V0 (the inverse of the initial reaction velocity). The equation of the Lineweaver-Burk plot can be expressed as:

[ \frac{1}{V_0} = \frac{Km}{Vmax} \cdot \frac{1}{[S]} + \frac{1}{Vmax} ]

From this equation, it's clear that the Y-intercept is equal to 1/Vmax. Therefore, when you plot the data points from an enzyme activity experiment, the point where the line intersects the Y-axis gives the reciprocal of the maximum reaction velocity (Vmax), allowing you to determine it from your experimental data. This aspect is critical for understanding enzyme dynamics and efficiencies in a biological context.