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
Tong, Liang. "Structure and function of biotin-dependent carboxylases." Cellular and Molecular Life Sciences 70, no. 5 (2013): 863-891. [Source]
Yang, Wei, Jae Young Lee, and Marcin Nowotny. "Making and breaking nucleic acids: two-Mg2+-ion catalysis and substrate specificity." Molecular Cell 22, no. 1 (2006): 5-13. [Source]
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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