Enzyme Kinetics

NewsGuard 100/100 Score

Enzyme kinetics involves the measurement of the rate at which chemical reactions that are catalyzed by enzymes occur. Knowledge about the kinetics of an enzyme can reveal useful information about its catalytic mechanism, role in metabolism, factors that impact its activity, and mechanisms of inhibition.

This article will cover the basic principles of enzyme kinetics, including the reaction equation, rate of reaction and maximal velocity (Vmax) and Michaelis Constant (Km).

Rate of reaction

Enzymes are thought to form a complex with the substrates to catalyze the reaction. This process can be illustrated with the simplified equation, where e is the enzyme, S is the substrate, and P is the product:

E + S ⇔ ES ⇒ P + E

The first step of the equation, which is reversible, has the reaction rate constant of k+1 to produce the enzyme substrate complex and k-1 for the reverse reaction. The reaction rate constant for the second step of the equation, which is not reversible, is k+2.

The rate of reaction (v), which is the rate at which the product is formed, is defined by the following equation:

v = d[P]/dt = k+2[ES]

The square brackets in the above equation represent the molar concentration of the substance specified within, so [P] refers to the molar concentration of the product and [ES] the molar concentration of the enzyme substrate.

Vmax and Km

Leonor Michaelis and Maud Menten introduced a mathematical illustration to describe the action of enzymes with two constants, Vmax and Km.

The maximal velocity (Vmax) refers to the point at which the increase the concentration of the substrate does not increase the rate of a reaction catalyzed by an enzyme. This occurs because the substrate molecules saturate the active sites of the enzyme and are not able to form more complexes with the enzyme. This value is given as a rate (mmol/s), which is the maximum velocity of the reaction when the enzyme is saturated.

Michaelis–Menten saturation curve of an enzyme reaction. Parameter values used are Vmax=3.4 and Km=1.7.

The Michaelis constant (Km) is the concentration of the substrate when half of the active binding sites of an enzyme are occupied by the substrate. The constant helps to depict the affinity of the enzyme for their substrate. This value is given as the concentration of the substrate (mM) at half of Vmax. An enzyme with a high Km has a low affinity for the substrate, and a high concentration of the substrate is needed in order for the enzyme to become saturated. Conversely, an enzyme with a high Km has a high affinity for the substrate and the enzyme may become saturated even with a low amount of substrate.

Applications of enzyme kinetics

There are many practical uses of enzyme kinetics. For example, the kinetic constants can help explain how enzymes work and assist in the prediction of the behavior of enzymes in living organisms.

Vmax and Km both play a key role in understanding the metabolism of the human body. Knowledge of the enzyme kinetic constants allows us to gain a better understanding of the enzymes and processes that take place in human metabolism. This knowledge could then be used for medical purposes to improve patient health outcomes.


Further Reading

Last Updated: Jul 19, 2023

Yolanda Smith

Written by

Yolanda Smith

Yolanda graduated with a Bachelor of Pharmacy at the University of South Australia and has experience working in both Australia and Italy. She is passionate about how medicine, diet and lifestyle affect our health and enjoys helping people understand this. In her spare time she loves to explore the world and learn about new cultures and languages.


Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Smith, Yolanda. (2023, July 19). Enzyme Kinetics. News-Medical. Retrieved on June 12, 2024 from https://www.news-medical.net/life-sciences/Enzyme-Kinetics.aspx.

  • MLA

    Smith, Yolanda. "Enzyme Kinetics". News-Medical. 12 June 2024. <https://www.news-medical.net/life-sciences/Enzyme-Kinetics.aspx>.

  • Chicago

    Smith, Yolanda. "Enzyme Kinetics". News-Medical. https://www.news-medical.net/life-sciences/Enzyme-Kinetics.aspx. (accessed June 12, 2024).

  • Harvard

    Smith, Yolanda. 2023. Enzyme Kinetics. News-Medical, viewed 12 June 2024, https://www.news-medical.net/life-sciences/Enzyme-Kinetics.aspx.


The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
Post a new comment

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.

You might also like...
Genetic screening and counseling slash young adults' excessive drinking, new study reveals