Question

Denaturation followed by aggregation of proteins results in _______.

• A. increased solubility
• B. gel formation
• C. peptide bond cleavage
• D. increased enzymatic activity

Hint:

Protein gelation is a multi-step process: First, the protein denatures (unfolds), exposing active binding sites. Second, the molecules aggregate to build a three-dimensional network that traps water.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks about the physical result of protein denaturation followed by the cross-linking or grouping of the unfolded protein chains (aggregation).

Step 2: Key Concepts and Approach:
Proteins are folded polymers of amino acids.
Denaturation is the unfolding of the native structure (secondary, tertiary, and quaternary) without breaking the covalent peptide bonds.
Aggregation involves the interaction of these unfolded chains, driven by hydrophobic interactions, hydrogen bonding, and disulfide cross-linking.

Step 3: Detailed Explanation:

• Unfolding of Structure: When proteins are denatured by heat, acid, or mechanical action, hydrophobic groups that were previously buried inside the protein core are exposed.

• Network Formation: These newly exposed hydrophobic regions on different protein molecules begin to associate with each other to minimize contact with water.

• Gelation: If the protein concentration is high enough, this continuous, three-dimensional network can trap water, forming a semi-solid structure known as a gel.
Examples include the boiling of egg white (ovalbumin gelation) or the coagulation of soy milk to make tofu.

• Evaluating other options:
* Solubility decreases during denaturation and aggregation because hydrophobic groups are exposed and molecules become too large to remain dissolved.
* Peptide bond cleavage is hydrolysis, which is distinct from denaturation.
* Enzymatic activity decreases or is lost completely because denaturation alters the shape of the enzyme's active site.

Step 4: Final Answer:
Thus, denaturation followed by aggregation of proteins results in gel formation.