Q.57 Given below are two statements:
Statement–I: Weak interactions like hydrogen bonds and salt bridges stabilize protein folding.
Statement–II: Protein folding is assisted by chaperones.
In the light of the above statements, choose the most appropriate answer from the options given below.
- Both Statement–I and Statement–II are correct
- Both Statement–I and Statement–II are incorrect
- Statement–I is correct but Statement–II is incorrect
- Statement–I is incorrect but Statement–II is correct
Correct Answer: Both Statement–I and Statement–II are correct.
Both statements accurately describe key aspects of protein folding. Weak interactions provide the thermodynamic stability for the native conformation, while chaperones kinetically assist the process to avoid misfolding.
Statement–I Analysis
Weak interactions like hydrogen bonds (backbone H-bonds in α-helices/β-sheets) and salt bridges (ionic bonds between charged side chains, e.g., Asp-Arg) stabilize the folded state. These non-covalent forces contribute ~1-5 kcal/mol each, collectively overcoming unfolding entropy.
Statement–II Analysis
Protein folding is assisted by chaperones like Hsp70 and GroEL, which prevent aggregation of unfolded polypeptides and provide a protected environment for folding. They do not provide folding energy but facilitate correct pathway selection.
Option Breakdown
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Both correct: Selected; Statement–I addresses equilibrium stability, Statement–II addresses folding kinetics—complementary mechanisms.
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Both incorrect: Wrong; both are textbook facts in molecular biology.
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Statement–I correct, Statement–II incorrect: Invalid; chaperones are essential, especially for larger proteins (>~300 residues).
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Statement–I incorrect, Statement–II correct: False; without weak interactions, even chaperone-assisted chains would not maintain folded structure.
Introduction to Protein Folding Weak Interactions Chaperones
Protein folding weak interactions chaperones represent core molecular biology concepts: hydrogen bonds/salt bridges drive stability, while chaperones prevent misfolding during synthesis. Both statements are correct for native conformation.
Role of Weak Interactions
Hydrogen bonds stabilize secondary structures; salt bridges reinforce tertiary folds via electrostatics. Hydrophobic effect (not mentioned but primary) buries nonpolar cores, with van der Waals filling voids.
Chaperone Assistance Mechanism
Hsp60/70 bind hydrophobic regions of nascent chains, using ATP hydrolysis for release. GroEL/ES forms a cage for iterative folding trials, critical in crowded cellular environments.
Exam Context for Life Sciences
GATE/NEET questions test Anfinsen’s dogma (sequence determines structure) alongside chaperone roles. Misfolding links to amyloid diseases, relevant to your molecular biology focus.
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