Kinetics of Enzymatic Reactions: The Michaelis-Menten Equation

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The rate limiting step in the enzyme catalyzed transformation of substrate S into product P is the breakdown of the ES complex:

Since the ES concentration is not easily measured experimentally, Leonor Michaelis and Maud Menten have given an alternative expression for the determination of the rate of such enzymatic reactions: where KM, the Michaelis constant is defined as:

Several algebraic transformations to a linear form have been proposed for this equation which are more useful in the analysis of the experimental data: Lineweaver-Burk, Eadie and Dixon.

Given the following data for the hydrolysis of sucrose by the enzyme invertase, find which equation has the best correlation coefficient, determine the Michaelis constant and kb - the maximum turnover number:

k0.1820.2650.311 0.3300.349 0.3490.3720.371

In the Dixon expression, which has the best correlation, the substrate concentration [S] is correlated to the ratio of the substrate concentration [S] to the rate k. The maximum turnover number is the reciprocal of the slope, and the Michaelis constant is the product of the intercept with the maximum turnover number.


  1. Calculate the Michaelis constant and the maximum turnover number according the other two equations. Are the differences significant?

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