Q.36 Triple-helical coiled coil structure is characteristic of:
- Cellulose
- Collagen
- Elastin
- Chymotrypsin
Triple-helical coiled coil structure is characteristic of Collagen. This biochemistry question tests protein structure knowledge crucial for NEET exams.
Correct Answer Explanation
Collagen features a unique triple-helical coiled coil structure where three polypeptide chains (rich in glycine, proline, hydroxyproline) wind around each other in a rope-like superhelix, providing tensile strength to connective tissues.
Option Analysis
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Cellulose: Polysaccharide (β-1,4 glucose), linear chains with hydrogen bonds forming microfibrils – no protein, no triple helix.
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Collagen: Correct – Triple helical coiled coil (Gly-X-Y repeat), most abundant animal protein.
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Elastin: Cross-linked random coil structure for elasticity, no triple helix.
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Chymotrypsin: Globular serine protease with α-helices and β-sheets, no triple helix.
Introduction to Triple-Helical Coiled Coil Structure
Master triple-helical coiled coil structure characteristic of Collagen for NEET biochemistry. Unlike Cellulose (polysaccharide), Elastin (elastic fibers), or Chymotrypsin (enzyme), only Collagen forms the unique triple helix essential for tendon/ligament strength.
Protein Structure Breakdown
Collagen (Triple helix): Three α-chains form supercoiled rope (Gly every 3rd residue, Pro/Hyp stabilize). Types I-V for different tissues.
Cellulose: Plant cell wall β-glucose polymer – straight chains, H-bond sheets.
Elastin: Hydrophobic cross-links (desmosine) for stretch-recoil, amorphous coils.
Chymotrypsin: Compact globular fold with catalytic triad (Ser-His-Asp).
Why Collagen is the NEET Answer
Triple helix = hallmark collagen feature (25% body protein). Exam trap: confusing with α-helical coiled coils (myosin) vs collagen’s unique triple helix.
Exam Memory Aid
“Triple-Collagen: Three ropes twisted = Collagen fibers.” Skip Cellulose (carbs), Elastin (stretchy), Chymotrypsin (digestive).
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