Which secondary protein structural motif is stabilized by intramolecular hydrogen bonds between peptide carbonyl (C=O) and amino (N-H) groups?
Answer and explanation
Correct answer: D. Alpha-helix and Beta-pleated sheet
- Step 1: Linus Pauling determined that regular hydrogen bonding along the polypeptide backbone creates secondary structures. Step 2. Alpha-helices (hydrogen bond between residue n and n+4) and beta-pleated sheets are the two primary stabilized motifs. Answer: Alpha-helix and Beta-pleated sheet. Why not the others: Primary sequence is covalent peptide bonds; disulfide bridges are tertiary covalent bonds between cysteines; hydrophobic core is non-polar aggregation.
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