Question

Which of the following are true about chymosin?
A. is commonly known as rennin
B. is used in cheese making
C. is a protease enzyme
D. is an essential amino acid
Choose the most appropriate answer from the following:

• A. A and B only
• B. B and D only
• C. A, B and C
• D. B, C and D

Hint:

Chymosin Facts: Chymosin = RENNIN (Aspartic Protease enzyme, EC 3.4.23.4). Primary coagulant in cheese making. Cleaves $\kappa$-casein at Phe105-Met106.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Enzymology of milk coagulants: Chymosin (rennin, EC 3.4.23.4) is an aspartic endopeptidase extracted from the abomasum of suckling calves that specifically cleaves $\kappa$-casein to coagulate milk in cheese manufacturing.
Key Formula or Approach:
\[ \text{Chymosin (Rennin, Aspartic Protease)} + \kappa\text{-Casein (169 AA)} \xrightarrow{\text{Cleaves Phe105-Met106}} \text{Para-}\kappa\text{-Casein (1--105)} + \text{Glycomacropeptide (106--169)} \]

Step 2: Detailed Explanation:
Characteristics of Chymosin in cheese technology and enzymology:
1. A. True: Chymosin is commonly known as Rennin (historically extracted from the gastric mucosa of the fourth stomach abomasum of unweaned suckling calves).
2. B. True: It is universally the primary milk-clotting coagulant used in cheese making around the world.
3. C. True: It is an aspartic endopeptidase (protease enzyme) that specifically cleaves the Phe105-Met106 peptide bond of $\kappa$-casein.
4. D. False: It is a $36\text{ kDa}$ catalytic globular protein, NOT an amino acid.
- Therefore, statements A, B, and C are true.

Step 3: Final Answer:
Thus, the correct statements are A, B and C, matching option (C).