What is a non-integral repeat in an alpha helix?

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    • #16750
      qwertyqwerty
      Participant

      What exactly is a non-integral repeat in an alpha helix and how does it arise? I was doing a question:

      An a helix is a form of protein secondary structure with 3.6 residues per turn of helix. The non-integral repeat arises because it:
      a) allows the formation of base pairs on the inside of the helix
      b) prevents clashes between neighbouring amino acid side chains
      c) positions the C=O and N-H groups to give favourable linear hydrogen bonds
      d) leads to formation of an amphipathic helix

    • #112092
      JackBean
      Participant

      you should ask that rather on mathematical forum 😉 it means the number of residues is 3.6 and not 3 or 4, i.e. there is something after the coma.

    • #112099
      biorules
      Participant

      c) positions the C=O and N-H groups to give favourable linear hydrogen bonds

    • #112102
      JackBean
      Participant

      I think b) is more important, because if it was exactly 4, then you would have all amino acids stacked one above other. Also, I think the hydrogen bonds in helix are not exactly linear.

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