Enzyme Components and Functions

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What is a holoenzyme?

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A complete, active enzyme consisting of an apoenzyme (protein part) and a cofactor (non-protein part). It is the functional form of the enzyme.

Front

What is an apoenzyme?

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The inactive protein part of an enzyme that requires a cofactor to become active.

Front

What is a prosthetic group?

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A tightly or permanently bound non-protein component of an enzyme, which is essential for its activity (e.g., heme in hemoglobin).

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What is a coenzyme?

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A loosely bound organic molecule (often derived from vitamins) that assists enzyme function by carrying chemical groups or electrons (e.g., NAD⁺, FAD, Coenzyme A).

Front

What is a cofactor?

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A non-protein substance (which can be an inorganic ion or organic molecule) required for enzyme activity. It includes both metal ions (e.g., Mg²⁺, Zn²⁺) and coenzymes.