AAMC FL Practice Exam

What does a Lineweaver-Burk plot demonstrate?

1. Different Vmax values impact y-intercepts

2. Different substrates affect the x-axis

3. All enzymes have equal Km values

4. It cannot be used with competitive inhibitors

The correct answer is: Different Vmax values impact y-intercepts

A Lineweaver-Burk plot, also known as a double-reciprocal plot, is a graphical representation used in enzyme kinetics to illustrate the relationship between the rate of an enzyme-catalyzed reaction and the concentration of substrate. This plot is derived from the Michaelis-Menten equation and is commonly utilized to determine key kinetic parameters such as Vmax (maximum reaction velocity) and Km (Michaelis constant). The correct understanding is that different Vmax values result in variations in the y-intercept of the Lineweaver-Burk plot. In this plot, the y-axis represents the reciprocal of the reaction velocity (1/v), while the x-axis represents the reciprocal of the substrate concentration (1/[S]). The y-intercept occurs at 1/Vmax, meaning that as Vmax varies due to different enzyme conditions or saturations, the y-intercept will change accordingly. This is critical for interpreting enzyme activity and understanding how modifications in enzyme concentration or efficiency can affect overall reaction rates. Contextually, the other options do not accurately reflect the purpose or implications of the Lineweaver-Burk plot. For example, the effect of different substrates on the x-axis is not a primary feature since the plot demonstrates the same enzyme behavior with varying