2.4.1-Cofactors, Coenzymes, Prosthetic Groups

What are cofactors?

inorganic substance, non-protein components of an enzyme necessary for its function.

They fit into the active site and activate the enzyme.

Example of a cofactor

Amylase requires a chloride ion for its active site to be correct shape. catalyses breakdown of starch.

What are coenzymes?

Large organic substances, that are involved in some chains of enzyme-controlled reactions.

Example of a coenzyme

vitamin B3 synthesises NAD - transfers H+ between molecules involved in respiration

Also, NADP from vitB3and

vitamin B5. used to make coenzyme A - ! in breakdown of fatty acids & carbs in respiration

What do cofactors and coenzymes do?

May form part of active site of enzyme.
May transfer atoms/groups from 1 reaction -> another in multi-step pathway

What are prosthetic groups?

A cofactor that is a permanent part of an enzyme is called a prosthetic group

tightly bound = permanent feature of enzyme

Example of prosthetic group

Zn2+ part of structure of carbonic anhydrase (enzyme that metabolises CO2)