Question

Vitamins are generally involved in forming a component of the enzyme called
(a) Apoenzyme
(b) Holoenzyme
(c) Prosthetic group
(d) Coenzyme

Answer 1

Hint: Vitamins are a group of organic compounds which are required by the body in trace quantities. One of their vital functions includes forming a component of the enzyme and activating their catalytic function.

Complete answer:
Enzymes are composed of one or more polypeptide chains ( except Ribozymes which are RNA molecules with catalytic ability). Most of the enzymes require non-protein groups for their biological activity. These are called cofactors. The protein portion of the enzyme is called an apoenzyme, which is generally inactive. The complete, biologically active conjugated enzyme (apoenzyme + cofactor) is referred to as holoenzyme.
Cofactors can be simple inorganic metal ions or a complex of organic molecules collectively called coenzymes.
Coenzymes are further classified as co-substrates and prosthetic groups based on their disassociation abilities. Prosthetic groups remain tightly bound to the apoenzyme. Like Haem in catalase and peroxidase.
Cosubstrates are transiently bound to the apoenzyme and act as carriers of chemical groups or atoms or electrons. Most of these loosely bounded coenzymes or cosubstrates are derivatives of vitamins. In fact, all the water-soluble and two of the fat-soluble vitamins are precursors of coenzymes.

Additional Information: Some examples of vitamins and their coenzyme forms are:
-The coenzyme ‘Thiamine pyrophosphate’ is derived from Vitamin B1 or Thiamine. It participates in oxidative decarboxylation reactions of carbohydrate metabolism.
-FAD and FMN are some of the common coenzymes serving as hydrogen carriers in the citric acid cycle and electron transport chain of respiration. They are derived from vitamin B2 or Riboflavin.
-Vitamin K is a coenzyme of gamma-glutamyl carboxylase. This enzyme is used for calcium binding in the bones.
So, the correct answer is ‘ Coenzyme.’

Note: Vitamins perform several important cellular functions. Their requirements need to be fulfilled in a diet as our body is unable to synthesize them. Based on their solubilities, they can be classified into water-soluble and fat-soluble vitamins. Four vitamins i.e A, D, E, K are fat-soluble while vitamin B-complex and C are water-soluble. Their concentration in the body below an optimal level causes deficiency like low Vitamin A leads to night blindness.