Question

Which one is not a cofactor?
(a)Coenzyme
(b) Apoenzyme
(c)Prosthetic group
(d)Metal ion

Answer 1

Hint: This protein is also known as an inactive enzyme because they need cofactors to become active or to be in action. They can also speed up the biochemical processes.

Complete step by step answer:
An apoenzyme is an inactive enzyme and not a cofactor. The activation of the apoenzyme occurs only with the binding of an organic or inorganic cofactor. A cofactor is a non-protein chemical compound or metallic ion that is required to activate an enzyme. That is why cofactors can be considered as the "helper molecules” that assist in biochemical transformations.

So, the correct answer is, 'Apoenzyme'.

Additional information: -Cofactors are generally divided into two main groups: organic cofactors, that include flavin or heme, and inorganic cofactors, that include the metal ions ${Mg^{2+}}$, ${Cu^{+}}$, ${Mn^{2+}}$, or iron-sulfur clusters. The organic cofactor can either be a coenzyme or a prosthetic group.
-Most cofactors aren't covalently bound but instead are tightly bound. However, organic prosthetic groups like an iron ion or a vitamin are often covalently bound. Examples of holoenzymes are DNA polymerase and RNA polymerase that consists of multiple protein subunits. All the subunits necessary for activity are contained by the complete complexes.
-A coenzyme is a cofactor that is loosely bound to the enzyme and therefore may be released readily from the active site of the enzyme. Examples of coenzymes are those made from water-soluble vitamins i.e. B vitamins and vitamin C, and elements such as Cu, Ca, Zn, Mg, K, Ni, Co, Fe, etc. A prosthetic group is the group of elements that are firmly attached to the enzyme.
-To catalyze a reaction, a coenzyme which is an organic non-protein compound, binds with an enzyme. Coenzymes are often broadly called cofactors, but they're chemically different.
-A coenzyme cannot function alone but is often reused several times when paired with an enzyme.
-Coenzymes are non proteins organic molecules that are mostly derivatives of water-soluble vitamins; they bind apoenzyme molecules to supply active holoenzyme.

Note:
-An apoenzyme is a type of enzyme that is without a coenzyme and activation of this enzyme depends upon its binding with an organic or inorganic cofactor.
-Together with its cofactor an apoenzyme is called a holoenzyme. It is very much complete and catalytically active too.
-To catalyze a reaction, a coenzyme which is an organic non-protein compound binds with an enzyme. Coenzymes are often broadly called cofactors, but they're chemically different.