Question

1. How are prosthetic groups different from co-factors?

Answer 1

Cofactors

Cofactors are the non-protein components bound to enzymes to make them catalytically active.

Protein portion of an enzyme is called apoenzyme.

3 kinds of co-factors: prosthetic groups, co-enzyme and metal ions

• • Prosthetic group − binds tightly to the apoenzyme; e.g., haem (part of the active site of an enzyme)

  • Co-enzyme − association with apoenzyme is transient; occurs only during the course of catalysis; e.g., NAD and NADP

  • Metal ions − basically required to form coordination bonds with side chains of the active site, and with the substrate; e.g., carboxypeptidase contains Zn