Question

An organic substance that binds to the enzyme and is essential for its activity, is called-

• A. holoenzyme
• B. apoenzyme
• C. isoenzyme
• D. coenzyme

Answer 1

The correct option is D

coenzyme

The correct option is D

Explanation of correct option

1. Coenzymes refer to organic compounds like vitamins or their derivatives that help in catalyzing an enzymatic reaction.
2. Flavin adenine dinucleotide (FAD), nicotinamide adenine dinucleotide phosphate (NADP), and nicotinamide adenine dinucleotide (NAD) are coenzymes that help in hydrogen transfer or oxidation.

Explanation of incorrect option

Option A

1. Holoenzymes refer to the bioactive combination of enzyme and coenzyme molecule that together catalyzes a reaction.
2. Examples- RNA polymerase and DNA polymerase require all the sub-units and cofactors to come together to form an active biomolecule for carrying out the replication of RNA and DNA respectively.

Option B

1. Apoenzymes refer to the inactive portion of the enzyme that requires the addition of a cofactor or a coenzyme to carry out the reaction.
2. Examples of cofactors include iron or magnesium ions or coenzymes like NAD or FAD for the reaction to occur.
3. Examples of apoenzymes are hemoglobin, carbonic anhydrase, cytochrome oxidase, etc.

Option C

1. Isozymes refer to different enzymes that catalyze a specific reaction but differ in their enzymatic form and efficiency of catalysis.
2. They can be identified using their different electrophoretic mobility.
3. Lactic dehydrogenase, creatine kinase, amylase, hexokinase, alkaline phosphatase, etc. have multiple isoenzymes.

Final answer

An organic substance that binds to the enzyme and is essential for its activity, is called a coenzyme.