Question

Non-protein organic component of the enzyme is
A. Apoenzyme
B. Holoenzyme
C. Coenzyme
D. Isoenzyme

Answer 1

Hint: Enzymes are protein molecules that help speed up the reaction rate of various metabolic activities in the body. The enzyme cannot function directly. It needs various other factors to activate it. A cofactor or an inorganic molecule when attached to an enzyme, it activates it.

Complete answer: An enzyme is a protein molecule that binds to a substrate and increases the rate of reaction of its conversion. An enzyme works by binding to various other molecules. These molecules are apoenzyme, holoenzyme, and coenzyme. During a metabolic process, an enzyme catalyzes the chemical reaction. The protein part of the enzyme which needs to get activated for the functioning of the enzyme is called apoenzyme. The apoenzyme gets activated through the attachment of additional organic or inorganic cofactor. These cofactors are organic chemicals and not protein molecules. They are called coenzymes. They attach loosely to the apoenzyme and activate it. The complex formed between an apoenzyme and a coenzyme is called a holoenzyme. After the reaction is complete it detaches itself from the enzyme. A tightly bound coenzyme on the other hand is called a prosthetic group. Thus, coenzymes function as an important factor in the working of enzymes. Isoenzymes are enzymes that have different structures but perform a similar function. This means that they aid in the same metabolic reactions but require different cofactors for their activation. This is due to structural changes.
Therefore, the right answer is option C.

Note: The coenzymes themselves get conformational changes during the catalysis action of enzymes. They may require additional enzyme-catalyzed reactions so as to restore them into their real or original state. Nicotinamide adenine dinucleotide or NAD is an example of coenzyme.