Summary
Non-protein helpers such as metal ions or vitamin-derived molecules that many enzymes require to function.
In depth
Inorganic cofactors include Zn2+, Mg2+ and Fe2+. Organic coenzymes, such as NAD+, FAD and coenzyme A, carry electrons or chemical groups between enzymes. A tightly bound one is a prosthetic group, and the enzyme without it is an apoenzyme.
Many vitamins are coenzyme precursors, so deficiency stops key reactions.
Many vitamins give rise to coenzymes: niacin to NAD+, riboflavin to FAD, pantothenate to coenzyme A, thiamine to thiamine pyrophosphate and folate to tetrahydrofolate. Coenzymes often act as co-substrates, being changed and then regenerated by another enzyme.
Metal ions help by stabilising negative charges, binding substrates or taking part in redox changes. Heavy metals such as lead and mercury poison enzymes by displacing the normal metal or binding to sulfhydryl groups.
Remember: apoenzyme plus cofactor makes the holoenzyme, which is the active form.
Frequently asked questions
What is Cofactors and Coenzymes?
Non-protein helpers such as metal ions or vitamin-derived molecules that many enzymes require to function.
Which area of biology covers Cofactors and Coenzymes, and how advanced is it?
Cofactors and Coenzymes is one of the 51 topics in Biomolecules & Biochemistry. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Vitamins, Induced Fit Model, Active Site.
Can you give an example of Cofactors and Coenzymes?
Carbonic anhydrase needs zinc to convert CO2 and water to bicarbonate.
What should I learn before Cofactors and Coenzymes?
Work through the Beginner topics in Biomolecules & Biochemistry first, such as Water Properties, Carbon Chemistry, Carbohydrates, then return to Cofactors and Coenzymes. Intermediate topics assume the Beginner vocabulary.
What topics are related to Cofactors and Coenzymes?
The closest topics to Cofactors and Coenzymes are Vitamins, Induced Fit Model, Active Site, Noncompetitive Inhibition. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Cofactors and Coenzymes?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Cofactors and Coenzymes. To practise the whole of Biomolecules & Biochemistry, use the Biomolecules & Biochemistry quiz.
How is Cofactors and Coenzymes different from Vitamins?
Cofactors and Coenzymes: Non-protein helpers such as metal ions or vitamin-derived molecules that many enzymes require to function. Vitamins: Organic micronutrients needed in small amounts, often serving as coenzymes in metabolic reactions. Read both side by side and note what each one explains.
How should I study Cofactors and Coenzymes step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Vitamins and explain the difference aloud. Finally, take the Biomolecules & Biochemistry quiz and come back to this page for any question you miss.