Question

How many divisions of enzymes have been suggested by International Union of Biochemistry?

• A. 10
• B. 6
• C. 7
• D. 3

Hint:

Mnemonic for 6 IUB enzyme classes: OTHLIL (Oxidoreductases, Transferases, Hydrolases, Lyases, Isomerases, Ligases).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The Enzyme Commission (EC) of the International Union of Biochemistry and Molecular Biology (IUBMB) classifies enzymes into systematic functional classes based on the chemical reaction catalyzed.
Key Formula or Approach:
\[ \text{IUBMB Enzyme Classes: } \text{OTHLIL (Classes 1 to 6)} \]

Step 2: Detailed Explanation:
The classical systematic enzyme classification established by the IUBMB designates 6 primary enzyme divisions (EC classes):
1. EC 1 - Oxidoreductases: Catalyze oxidation-reduction reactions.
2. EC 2 - Transferases: Transfer chemical functional groups.
3. EC 3 - Hydrolases: Hydrolysis of covalent bonds.
4. EC 4 - Lyases: Non-hydrolytic addition or cleavage of groups forming double bonds.
5. EC 5 - Isomerases: Geometric or structural isomerizations.
6. EC 6 - Ligases: Synthetases coupling bond formation with ATP hydrolysis.
(A 7th class, Translocases, was created in 2018; standard examination questions reference the 6 major classical divisions).

Step 3: Final Answer:
Therefore, the number of major divisions suggested by IUB is 6, matching option (B).