- 1). Calculate the inverse of both sets of data. Divide one by each data point. For example, the inverse of the first substrate concentration value is 0.40 mM, or 1/2.5 = 0.40 mM. The inverse of the substrate concentrations are 0.400, 0.200, 0.100, 0.067, and 0.050 mM. The inverse values of the initial velocities are 41.67, 27.78, 18.87, 16.67 and 15.63 (mM sec-1).
- 2). Use a graphing calculator or software to plot a graph with the inverse values. The 1/[s] values are plotted along the x-axis and 1/v (time values) are plotted along the y-axis.
- 3). Complete a linear regression for the data points. The linear regression yields the equation for the straight-line, y = mx + b. The m value equals the slope of the line. The b value equals the y-intercept. The equation is y = 75.46x + 11.791 based on the listed data points. The y-intercept represents the Vmax value for the enzymatic assay.
- 4). Calculate the inverse of the y-intercept by dividing one by the y-intercept (1/11.791 = 0.0847 mM sec-1). Vmax is equal to the inverse of the y-intercept value.