Question

Which of the following enzymes has the lowest pH optimum?
a. Pepsin
b. Trypsin
c. Salivary amylase
d. Pancreatic amylase

Answer 1

Hint: The above-given enzymes are associated with the digestion of food. They break down the food into macromolecules such as lipids, carbohydrates, proteins, amino-acids.

Complete answer:
Enzymes are the catalyst which is produced by a living organism to make certain biochemical reactions happen.

Coming to the above given options, Lets identify where these enzymes are produced.
• Option A suggests pepsin, which is present in the stomach.
• Option B stats Trypsin which is present in the small intestine.
• Option C suggests salivary amylase which is present in saliva (mouth).
• Option D suggests pancreatic amylase which is produced by the pancreas and presents in the small intestine.

All these enzymes are affected by pH. At the pH where enzymes are most active, is known as optimum pH. Higher or lower pH than optimum pH leads to loss of function of an enzyme. The optimum pH of these enzymes is shown below in the table.

Enzyme	pH Optimum
Pepsin	1.5 – 1.6
Trypsin	7.8 – 8.7
Salivary amylase	4.6 – 5.2
Pancreatic amylase	6.7 – 7.0

Hence, the correct answer is option (A).

Note: The easiest way to remember pepsin’s optimum pH is that it’s present in the stomach. We know that the stomach contains hydrochloric acid which is capable of dissolving metals. Pepsin works in such a condition. Pepsin breakdown bigger protein molecules into smaller protein molecules and it requires an optimum pH of 1.5 to 1.6 to work efficiently.