How do you measure kcat

The V max is the maximum enzyme velocity extrapolated out to very high concentrations of substrate. It is expressed in the same units you used to enter your Y values enzyme activity. If you know the concentration of enzyme sites you've added to the assay E t then you can calculate the catalytic constant K cat. Vmax and the Y values enzyme velocities are expressed in units of concentration per time, and Et must be entered in those same concentration units.

Distinguish the concentration of enzyme molecules from the concentration of enzyme sites. For example, if the enzyme is a dimer with two active sites, the molar concentration of sites is twice the molar concentration of enzyme.

When calculating K cat , the concentration units cancel out, so K cat is expressed in units of inverse time. It is the turnover number -- the number of substrate molecule each enzyme site converts to product per unit time.

You can also determine the K cat directly by fittng this model to your data. Determine the concentration of the enzyme in the original assay see the raw data. Note: the enzyme concentration is the same for all of the test tubes; only the substrate concentrations vary in the assay. The result is the value of Kcat.

Repeat Steps 1, 2 and 3 for the rest of the test tubes in the assay. Divide 1 by the result from Section 2, Step 3 to calculate the actual value of Vmax.

How to Calculate Initial Rate of Reaction. How to Calculate Vmax Lineweaver. How to Plot a Michaelis-Menten Curve. How to Measure the Optimum Temperature for an Enzyme. Activation Energy of the Iodine Clock Reaction. How to Write a Rate Law in Chemistry. How to Calculate Interstitial Velocity. Reaction rate lets you write equations to determine how different amounts of reactants lead to how much products you have.

These different equations let you use the one most appropriate for whatever purpose you need whether it's the rate of bacteria reproduction or the rate of ignition between fuels and gas.

You can even use these equations in combining both experimental observations with theoretical models and calculations.

You can learn about the significance of the Michaelis Menten equation methods through these different ways of defining reaction rate. These are systems that let microorganisms grow in an optimum environment, one that can produce as much product as possible. Bioreactors are even used in making fermented foods in some Asian countries.

After studying physics and philosophy as an undergraduate at Indiana University-Bloomington, he worked as a scientist at the National Institutes of Health for two years. He primarily performs research in and write about neuroscience and philosophy, however, his interests span ethics, policy, and other areas relevant to science. Related Articles How to Calculate Km.