How to Plot a Michaelis-Menten Curve

Understanding the Michaelis-Menten Equation

• 1

  Understand the purpose of each value in the equation and what it represents. V is the rate of conversion or the reaction rate, [S] is the substrate concentration, Vmax is the maximum rate of conversion, and Km (the Michaelis constant) is the substrate concentration at which the rate of conversion is half of Vmax.

• 2

  Find the values for each variable in the equation. [S] is the known concentration for the substrate being analyzed, and changing this value will affect the rate of the enzyme-catalyzed reaction. Km and Vmax values are usually listed with the substrate as well in terms of millimoles and sec-1 when given in a problem.

• 3

  Solve the appropriate equation for each value if the values are not given. According to the Mills College Biochemistry website, begin with the steady state equation k1[Efree][S] = (k-1 + k2)[ES]. Define Km using the equation Km-1 = k1/ (k-1 + k2). Solve for [ES] using the equation [ES] = [S][Et]/(Km + [S]) to get [Ef] and [S]. Use [Ef] to define Vmax using the equation vmax = kcat [Et]. Consult a college level biochemistry guide or textbook for detailed instructions on how to solve each of these equations and for specific definitions of each variable.

• 4

  Insert Km, [S] and Vmax into the Michaelis-Menten equation and solve for V, the velocity or rate of reaction.

Plotting the Michaelis-Menten Curve

• 5

  Using graph paper, draw an x- and y-axis. Label the x-axis mM of [S] or concentration of substrate. Label the y ax- sec/micro-mole of V or velocity of reaction.

• 6

  Insert different values of [S] into the Michaelis-Menten equation, along with the values found for Km and Vmax, to solve for V.

• 7

  Plot the values for [S] on the x-axis and the corresponding solved values for V on the y-axis. The graph should look like a rectangular hyperbola where higher concentrations of substrate equate to faster enzymatic reactions.