Enzymatic Reactions: Inhibitors and Activators

Deedhiti Patel, Kristin Klucevsek
  • Author
    Deedhiti Patel

    My name is Dee Patel and I am a current dental student in my third year! I graduated from the University of Massachusetts in 2018 with my degree in Biology. There, I also worked as a biology tutor and teachers assistant for freshman biology.

  • Instructor
    Kristin Klucevsek

    Kristin has taught college Biology courses and has her doctorate in Biology.

What are enzymatic reactions? Learn enzymatic definition and about the role of activators and inhibitors. Understand the process of inhibition by different types of inhibitors. Updated: 07/17/2021

Table of Contents


Enzymatic Reactions Definition

Enzymes act as catalysts to induce a biomechanical reaction within the body. By binding to molecules (which are more specifically called substrates) within the body, they induce a change within that substrate, and bring about a reaction. As a catalyst, enzymes not only bring about a reaction, but they also provide the means to speed up the reaction and allow it to be achieved within a faster time.

Enzymatic reactions are reactions in which enzymes bind to a substrate, induce a conformational change within that substrate, and then bring about a biomechanical reaction. An example of an enzymatic reaction would be sugar inversion in the presence of the invertase enzyme. Sucrose is a sugar which is naturally occurring in plants and is a disaccharide, composed of glucose and fructose. In the presence of invertase, sucrose is broken down into its two parts, glucose, and fructose.

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  • 0:05 Enzyme Regulation
  • 1:50 Competitive Inhibition
  • 3:27 Noncompetitive Inhibition
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Enzymatic Activators

Just as enzymes act like a catalyst to biomechanical reactions, there are also molecules that can affect the activity of the enzymes. Enzymatic activators are molecules that can increase the activity of an enzyme.

Examples of enzymatic activators are cofactors and coenzymes. Cofactors are usually metal ions and do not directly bind the enzyme to increase the activity of that specific enzyme. Coenzymes are usually organic molecules, which directly bind the enzyme to increase the activity of that specific enzyme.

Essential Enzymatic Activators

Essential enzymatic activators are those activators that are necessary and need to be present for enzyme activity to occur. For example, kinase is an enzyme that is responsible for phosphorylation, which makes it essential for human physiology, as it controls metabolism, regulation of cell signaling, and many other cell processes. However, kinase is an enzyme that requires the need of an activator. This activator is magnesium. Generally, two molecules of magnesium are needed for proper function of kinase to aid in the physiological health of the body.

Non-Essential Enzymatic Activators

Non- essential enzymatic activators are activators that do not necessarily need to be present for enzyme activity to occur. The reaction bought about by non-essential enzymatic activators can also be known as allosteric regulation. In the absence of the enzymatic activator, the enzyme is still in function and can bring about a biomechanical pathway. However, in the presence of the enzymatic activator it binds to the enzyme (at a place other than the active it) and increases its affinity to bind to the substrate. An example of a non- essential enzymatic activator is chloride and amylase. Amylase is a digestive enzyme and in the absence of chloride, it is seen that amylase does not perform as well as to when chloride is present.

Enzymatic Inhibitors

Enzymatic inhibitors are molecules that interact with enzymes and reduce its affinity for its substrate. These types of molecules are primarily used for pharmacological purposes, where the goal would be to inhibit a pathway. For example, acetylcholine is a neurotransmitter, which is extremely important for the function of the human body. Acetylcholinesterase inhibits the activity of acetylcholine, which can lead to neurodegenerative disease. In result, acetylcholinesterase inhibitors are given to inhibit the action of acetylcholinesterase.

Within enzymatic inhibitors there are reversible and irreversible inhibitors. Reversible inhibitors cause a rapid dissociation of the enzyme-inhibitor complex and can be overcome with an increase in substrate concentration. Irreversible inhibitors cause a slow dissociation of the complex and cannot be overcome by an increase in substrate concentration. Irreversible inhibitors alter the active site of the enzyme and ultimately cause the enzyme to be unable to act as a catalyst.

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Frequently Asked Questions

What is enzymatic reaction?

An enzymatic reaction is when an enzyme binds a substrate at its active site and catalyzes a reaction which leads to the formation of products.

What is an enzymatic cleaner?

An enzymatic cleaner is a cleaning product that utilizes enzymes in its composition. These enzymes are used to break down stains that can be found on surfaces.

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