What is the role of cofactors in enzyme activity?

What are Cofactors?

Cofactors are non-protein helpers that some enzymes need to work properly.

• Without them, the enzyme may not be active.
• They can be inorganic ions (like Mg²⁺, Zn²⁺, Fe²⁺) or organic molecules (like vitamins or coenzymes).

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Role of Cofactors in Enzyme Activity

1. Help in Binding
   • They help the enzyme hold the substrate tightly.
   • Example: Zn²⁺ in carbonic anhydrase helps bind water and CO₂.
2. Take Part in the Reaction
   • Some cofactors directly carry atoms or electrons during the reaction.
   • Example: NAD⁺ (from vitamin B₃) carries electrons in respiration.
3. Stabilize the Enzyme
   • They maintain the correct shape of the enzyme so it can work.
   • Example: Mg²⁺ keeps DNA polymerase stable during DNA copying.
4. Act as “Shuttles”
   • Coenzymes (organic cofactors) often act like small “couriers,” moving chemical groups from one reaction to another.

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Types of Cofactors

• Metal ions → Mg²⁺, Fe²⁺, Zn²⁺
• Coenzymes → NAD⁺, FAD, Coenzyme A
• Prosthetic groups → Heme in hemoglobin and cytochromes

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✅ In Short:

Cofactors are like helpers for enzymes.
They:

• Help the enzyme bind to the substrate,
• Carry atoms/electrons,
• Stabilize the enzyme,
• Make sure the reaction happens efficiently.

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