Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
A prosthetic group is a non-protein molecule that is tightly and permanently attached to a protein, aiding its function. These groups are essential for the biological activity of certain proteins, particularly enzymes.
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Prosthetic groups are integral to enzyme function, often participating directly in the catalytic process.
Common examples include heme in hemoglobin and cytochromes, which play crucial roles in electron transport during oxidative phosphorylation.
Unlike coenzymes, prosthetic groups are permanently bound to their proteins.
They can be organic molecules, metal ions, or metal-containing complexes.
In oxidative phosphorylation, prosthetic groups facilitate the transfer of electrons through the electron transport chain.
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Related terms
Coenzyme: A non-protein compound that binds loosely to an enzyme and assists in enzymatic activity.
Electron Transport Chain (ETC): A series of protein complexes that transfer electrons from electron donors to electron acceptors via redox reactions.
Cytochrome: A type of protein found within the ETC that contains heme as a prosthetic group and plays a key role in electron transfer during cellular respiration.