Multiple choice

The length of a helical section of a polypeptide chain of 40 residues will be

  1. 3.6 Ao

  2. 60 Ao

  3. 80 Ao

  4. 40 Ao
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An alpha-helix has 3.6 amino acid residues per turn with a pitch (vertical rise per turn) of 5.4 Å. For 40 residues: (40 / 3.6) × 5.4 = 60 Å. This is a standard calculation in protein secondary structure analysis.

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