Is Coenzyme an Enzyme: 7 Interesting Facts (Read This First)

In this article the topic of our focus is “Is Co-enzyme an Enzyme: 7 Interesting Facts (Read This First). We are providing the facts and detailed statements in support with the topic.

Coenzymes are the organic substances that assist an enzyme to enhance its natural function and improves the overall stability of the reaction. Vitamins or the vitamins derived from it are the common types of coenzymes. The coenzymes in addition to help the enzyme also act as catalysts when enzymes are not present but the effect is not promising.

An example of coenzyme is coenzyme A which catalysis the reactions involving the synthesis of fatty acids and is also involved in their oxidation. Coenzyme A also acts as a substrate for many enzymes. Coenzyme A is involved in both catabolic and anabolic reactions occurring inside the living cells.

Structure of Coenzymes

Coenzymes are small organic substances which act as carriers of electrons and chemical functional groups. Coenzymes sometimes act as substrates with the other substrates present in the chemical reaction. Coenzymes are formed and derived of vitamins and other nutrients. Coenzymes assists the transformation of substrates into the products with the help of enzymes.

Coenzymes are the types of cofactors and are also known as cosubstrates.  Certain vitamins also act as coenzymes for example, vitamin K.

is coenzyme an enzyme
Structure of Coenzyme A Image from Wikipedia

Examples of Coenzymes

Coenzymes such as, flavin adenine dinucleotide (FAD), nicotinamide adenine dinucleotide phosphate (NADP), nicotinamide adenine dinucleotide (NAD), are found to be involved in oxidation reactions or hydrogen transfer reaction. Coenzyme A, is also a coenzyme that mostly participate in the transfer reactions involving acyl groups.

NAD and Coenzyme A are the most widespread and most important coenzymes which are derived from vitamins. Both are the derivatives of enzymes, where NAD is derived from vitamin B3. NAD exists in two alternative forms which are together known as redox couple NAD+ and NADH and both are significant coenzymes.

Functions of coenzymes

Coenzymes are known as the organic molecules that assists the enzymes in their proper functioning. Functions of coenzymes are listed below;

  • Coenzymes function as the intermediate carriers of electrons in a chemical reaction which involves transfer of functional groups.
  • The presence of coenzymes is essential for the efficient functioning of the enzymes and to maintain their biological activity.
  • Coenzymes are small organic substances which binds to the active site of the enzymes with covalent bonds and does not affect the overall structure of the enzyme.
  • A single coenzyme molecule is enough for the enzyme to convert a large number of substrates into products.
  • Coenzymes actively participate in electron transport chain as an electron carrier and also in glycolysis and citric acid cycle.
  • Biochemical reactions occurring in the body are dependent on coenzymes for their regulation and to maintain the cell homeostasis.  

Why co-enzyme is not an enzyme?

The main reason why coenzymes are not enzymes is because all the enzymes are made up of amino acid molecules and hence known as proteins whereas coenzymes are not protein they are derived from vitamins. Coenzymes usually bears phosphate groups by carrying adenosine triphosphate (ATP).

Coenzymes are only functional when paired or bonded with an enzyme. Coenzymes can be used over and over again in corporation with an enzyme or multiple enzymes. Enzymes are proteins that participate in a chemical reaction as a catalyst without being used up whereas the coenzymes act as the assistant for the enzymes for the enzyme effectiveness.

is coenzyme an enzyme
Synthesis of Coenzyme-A Image from Wikipedia

How coenzyme is related with enzyme?

Coenzymes are functionally related to the enzymes. Coenzymes are specific to the active sites of an enzyme which is the site of the enzyme that works in the enzyme- substrate reaction. Enzymes and coenzymes form covalent bonds with each other as they are nonmetal organic substances.

Enzymes enhances the speed of a chemical reaction and are released at the end without being consumed in the reaction. Coenzymes, on the other hand are also known as second substrates or substrates as they undergo changes when the enzyme Is doing its function because the coenzymes bind to the active site of an enzyme which is also a binding site for substrates.

Difference between coenzyme and enzyme?

Enzymes are produced biologically in living organisms.Coenzymes are the molecules are required to improve the efficiency of the enzyme functioning.
Enzymes are proteins made up of small stretches of amino acids.Coenzymes are not proteins.
Enzymes are large in size.Coenzymes are small in size.
Enzymes are globular molecules.Coenzymes are organic molecules derived from the vitamins.
Enzymes are the natural catalysts work to speed up the chemical reactions.Coenzymes assist enzyme in their functioning by binding to the active site of the enzyme.
Enzymes remains the same till the end of the reaction and are released with the products as the end products.The structure of coenzymes undergoes changes during the chemical reaction.
Enzymes are highly specific in their actions and binds to specific substrates.Coenzymes are not that specific.
Enzymes needs substrates for their activation and to perform their function.Coenzymes are themselves known as second substrates.
Difference between Coenzyme and Enzyme

How does coenzyme help enzymes?

Coenzymes function to assist the enzymes in their normal functioning by binding their active sites. Enzymes are highly significant for all the chemical reactions occurring inside the cells and need substrates to fulfill their functions and also the coenzymes for an efficient reaction. Both substrates and coenzymes bind to the active site of the enzyme which is highly specific.

Coenzymes bind transiently with the active site of the enzyme and undergo structural changes during the reaction. Coenzymes are a type of cofactors that are utilized by the enzymes to perform better. Instead of gaining or losing the electrons during the chemical reaction a coenzyme shares the electrons and functional groups. Coenzyme is not an integral part of any chemical reaction, they are released at the end and recirculated back to the blood stream in the free state.

Is coenzyme a substrate?

A coenzyme becomes a substrate sometimes and is referred to as cosubstrate or second substrate for a number of enzymes involved in the chemical reactions. They play a role in transferring electrons or functional groups such as hydrogen, chemical groups or other electrons in a number of reactions.

An example of coenzyme as a substrate is coenzyme A. Coenzyme is a type of cofactor which can be used as a substrate for the synthesis of 3hydroxyl-3-methylglutaryl-coA in the liver. It is also used as a substrate for a variety of other reactions taking place inside the cells such as catabolism and anabolism. In certain reactions coenzymes bind along with the substrates at the active site of the enzyme.

Is acetyl a coenzyme or an enzyme?

Acetyl is a coenzyme not an enzyme that is involved in variety of biochemical reactions such as the metabolic reactions of proteins, carbohydrates and proteins where it functions to transfer acetyl group to the krebs cycle for the production of energy. It behaves as a cofactor in number of processes involving both catabolism and anabolism reactions.

Acetyl coenzyme A is known to be an intermediate of metabolic reactions which has been derived from metabolic pathways such as, glycolysis, amino acid degradation, and the oxidation of fatty acids. It plays an important role as an electron carrier in cellular respiration.


To conclude the article, we can say in accordance with the topic that coenzymes are not enzymes they assist the enzymes to perform their normal physiological function in transforming specific substrates into the products and are released with the products as the end products.

Sneha Sah

Hey! I am Sneha Sah, I have completed post graduation in Biotechnology. Science has always been fascinating to me and writing is my passion. As an academic writer my aim is to make Science easy and simple to learn and read. Reach me at-

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