Question

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
Assertion A : Trehalose is a non-reducing sugar possessing a powerful ability to stabilize membranes and proteins against dehydration.
Reason R : Trehalose is a disaccharide made up of two D-glucose residues linked with each other through their anomeric carbon atoms.
In light of the above statements, choose the correct answer from the options given below

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is NOT the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Hint:

Famous Non-reducing sugars: Sucrose and Trehalose.
Most disaccharides (Maltose, Lactose) have one free anomeric carbon and are reducing.
Non-reducing sugars are better for storage and stress protection because they don't react with amino groups of proteins!

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question focuses on the biochemical properties and structural basis of Trehalose, a sugar important in stress tolerance.

Step 2: Detailed Explanation:

• Analyzing Assertion A: Trehalose is found in bacteria, fungi, insects, and "resurrection plants." It acts as a pharmaceutical stabilizer and an environmental protectant. Its high glass transition temperature allows it to form a "sugar glass" that coats and protects delicate protein and membrane structures from mechanical stress during drying. Thus, Assertion A is true.

• Analyzing Reason R: Trehalose consists of two glucose molecules joined by an $\alpha, \alpha$-1,1-glycosidic bond. Since the bond involves both C1 atoms (the anomeric/carbonyl carbons), no free aldehyde or ketone group is available. This makes it a non-reducing sugar. Thus, Reason R is true.

• Logical Connection: The lack of a reactive reducing end (Reason) makes the molecule chemically inert and extremely stable. This stability is exactly what allows it to be such an effective protectant (Assertion) without reacting with the proteins it is trying to save (avoiding Maillard reactions). Thus, R is the correct explanation of A.

Step 3: Final Answer:
Both statements are correct, and the non-reducing structural nature of trehalose is the chemical reason for its biological role as a stabilizer.