Biology 9700 · AS & A Level · Proteins

Proteins — practice question

Hydroxyproline is formed when an -OH group is added onto the R-group of the amino acid proline. Hydroxyproline is a major component of collagen and helps to improve the stability of its structure. Which statement explains why adding an -OH group to proline could make collagen more stable?

  • AIt strengthens hydrogen bonding between the R-groups of adjacent polypeptide chains, resulting in a tertiary structure that is more resistant to heat denaturation.
  • BIt increases the number of sites available for the formation of hydrogen bonds within the secondary structure of collagen, resulting in more stable alpha helices.
  • CIt increases the formation of hydrogen bonds between R-groups and water molecules, which help to hold the chains of the collagen triple helix together by strengthening hydrophilic interactions.
  • DIt strengthens the quaternary structure of collagen by providing more sites for hydrogen bonding between the R-groups of distantly separated amino acids within the same polypeptide chain.

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