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4.5: Cofactors and Coenzymes

JoVE Core
Molecular Biology

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Cofactors and Coenzymes

4.5: Cofactors and Coenzymes

Enzymes require additional components for proper function. There are two such classes of molecules: cofactors and coenzymes. Cofactors are metallic ions and coenzymes are non-protein organic molecules. Both of these types of helper molecule can be tightly bound to the enzyme or bound only when the substrate binds.

Cofactors are present in ~30% of mature proteins. They are frequently incorporated into an enzyme as it is folded and are involved in the enzyme’s catalytic activity. Magnesium is an essential cofactor for over 300 enzymes in the human body, including DNA polymerase. In this case, the magnesium ion aids in the formation of the phosphodiester bond on the DNA backbone. Iron, copper, cobalt, and manganese are other common cofactors.

Many vitamins are coenzymes, as they are nonprotein, organic helper molecules for enzymes. For example, biotin—a type of B vitamin—is important in a variety of enzymes that transfer carbon dioxide from one molecule to another.  Biotin, vitamin A and other vitamins must be ingested in our diet, as they cannot be made by human cells.

Suggested Reading


Cofactors And Coenzymes Are Essential Molecules That Play Crucial Roles In Various Biochemical Reactions In The Body. Cofactors Are Inorganic Substances Such As Metals Or Metal Ions That Are Required For The Proper Functioning Of Enzymes. Coenzymes On The Other Hand Are Organic Molecules That Work Together With Enzymes To Facilitate Specific Chemical Reactions. They Often Act As Carriers Of Chemical Groups Or Electrons Aiding In The Transfer Of These Groups Between Different Molecules. Examples Of Cofactors Include Magnesium Ions (Mg2+) Zinc Ions (Zn2+) And Iron-sulfur Clusters. These Cofactors Can Bind To Enzymes And Help Them In Catalyzing Reactions By Providing Necessary Coordination Or Stabilizing Structures. Coenzymes On The Other Hand Can Be Derived From Vitamins Or Other Essential Nutrients. They Include Molecules Such As Nicotinamide Adenine Dinucleotide (NAD+) Flavin Adenine Dinucleotide (FAD) And Coenzyme A (CoA). These Coenzymes Participate In A Wide Range Of M

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