Cofactor
Cofactor
A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme's activity as a catalyst (a substance that increases the rate of a chemical reaction). Cofactors can be considered "helper molecules" that assist in biochemical transformations.
Types of Cofactors[edit | edit source]
Cofactors can be divided into two main types:
- Coenzymes: Organic molecules that are often derived from vitamins and are required for enzyme function. Examples include NADH, FADH2, and Coenzyme A.
- Prosthetic groups: Tightly bound cofactors that are integral to the enzyme's structure. Examples include heme in hemoglobin and cytochromes.
Role in Enzyme Activity[edit | edit source]
Cofactors are essential for the proper functioning of many enzymes. They can:
- Stabilize enzyme structure
- Participate in the enzyme's catalytic mechanism
- Assist in the binding of the enzyme to its substrate
Examples of Cofactors[edit | edit source]
- Metal ions: Such as magnesium (Mg²⁺), zinc (Zn²⁺), and iron (Fe²⁺/Fe³⁺).
- Vitamins: Many vitamins act as precursors to coenzymes. For example, vitamin B1 (thiamine) is a precursor to thiamine pyrophosphate (TPP).
Cofactor vs. Coenzyme[edit | edit source]
While all coenzymes are cofactors, not all cofactors are coenzymes. Coenzymes are a subset of cofactors that are organic molecules, whereas cofactors can also include inorganic ions.
Related Concepts[edit | edit source]
- Apoenzyme: The protein part of an enzyme, without its cofactor.
- Holoenzyme: The complete, active enzyme with its cofactor.
- Metalloenzyme: Enzymes that contain one or more metal ions as cofactors.
See Also[edit | edit source]
Related Pages[edit | edit source]
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Contributors: Prab R. Tumpati, MD