Cofactors and Coenzymes

Some enzymes need helpers to organize a substrate or to complete their specific function. These include prosthetic groups, cofactors and coenzymes.


A cofactor is a chemical compound which is non-protein in nature. It is attached to protein and is required for the biological activity of the protein. These are called the helper molecules. They help in the biochemical transformations in various bodily reactions. Cofactors are two types:


Prosthetic group


Coenzymes are a specific type of organic molecules which bind to enzymes or proteins and aid in their functioning. Enzymes are the proteins essential for the body to carry out various metabolic and biochemical reactions.They are not really enzymes as is suggested by ‘co’ in their name.The prefix ‘co’ means helpers as they help the enzymes to carry out their functions. They are loosely bound to enzymes. These are many coenzymes derived from vitamins.

Coenzymes attach to the active site of an enzyme and help them in recognition, attraction, and repulsion of substrates or products. It is the substrate at which the enzyme catalyses a reaction.

Prosthetic Group

Prosthetic groups are a type of cofactors which bind tightly to enzymes or proteins, often by a covalent bond. They can be organic or metal ions. Prosthetic groups can bind to proteins other than enzymes.

Difference between Cofactors and Coenzymes



Non-protein chemical compounds Non-protein molecules
Two types of cofactors: coenzyme and prosthetic group One of the two types of cofactors
Tightly of loosely bound to enzymes or proteins Loosely bound to enzymes only
Help in chemical tranformations Help the enzymes to carry out their functions


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