Biomolecules

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ÇØ-FÅÇTØRS

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These are non-protein constituents bound to the enzyme to make the

enzyme catalytically active.

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Apo-enzyme: Protein portion of the enzyme.

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Co-factor + Apoenzyme = Holoenzyme

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When the co-factor is removed from the enzyme, its catalytic activity is

lost. Co-factors are of 3 types:

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Prosthetic group: Organic compounds. Tightly bound to apoenzyme.

E.g. Haem in peroxidase and catalase which catalyse the breakdown of

hydrogen peroxide to water and oxygen.

(NEET 2019)

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Co-enzymes: Organic compounds. Loosely bound to apoenzyme. Many

co-enzymes contain vitamins. E.g. NAD and NADP contain niacin.

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Metal ions: They form co-ordination bonds with side chains at

active site and one or more co-ordination bonds with the substrate.

E.g. Zn is a cofactor for carboxypeptidase.

Notes