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Helix packing of leucine‐rich peptides: A parallel leucine ladder in the structure of Boc‐Aib‐Leu‐Aib‐Aib‐Leu‐Leu‐Leu‐Aib‐Leu‐Aib‐OMe
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AbstractThe packing of peptide helices in crystals of the leucine‐rich decapeptide Boc‐Aib‐Leu‐Aib‐Aib‐Leu‐Leu‐Leu‐Aib‐Leu‐Aib‐OMe provides an example of ladder‐like leucylleucyl interactions between neighboring molecules. The peptide molecule forms a helix with five 5→1 hydrogen bonds and two 4→1 hydrogen bonds near the C terminus. Three head‐to‐tail NH ċ O = C hydrogen bonds between helices form continuous columns of helices in the crystal. The helicial columns associate in an antiparallel fashion, except for the association of Leu ċ Leu side chains, which occurs along the diagonal of the cell where the peptide helices are parallel. The peptide, with formula C56H102N10O13, crystallizes in space group P212121 with Z = 4 and cell parameters a = 16.774(3) Å, b = 20.032(3) Å and c = 20.117(3) Å; overall agreement factor R = 10.7% for 2014 data with |Fobs| < 3σ(F); resolution 1.0 Å.
Title: Helix packing of leucine‐rich peptides: A parallel leucine ladder in the structure of Boc‐Aib‐Leu‐Aib‐Aib‐Leu‐Leu‐Leu‐Aib‐Leu‐Aib‐OMe
Description:
AbstractThe packing of peptide helices in crystals of the leucine‐rich decapeptide Boc‐Aib‐Leu‐Aib‐Aib‐Leu‐Leu‐Leu‐Aib‐Leu‐Aib‐OMe provides an example of ladder‐like leucylleucyl interactions between neighboring molecules.
The peptide molecule forms a helix with five 5→1 hydrogen bonds and two 4→1 hydrogen bonds near the C terminus.
Three head‐to‐tail NH ċ O = C hydrogen bonds between helices form continuous columns of helices in the crystal.
The helicial columns associate in an antiparallel fashion, except for the association of Leu ċ Leu side chains, which occurs along the diagonal of the cell where the peptide helices are parallel.
The peptide, with formula C56H102N10O13, crystallizes in space group P212121 with Z = 4 and cell parameters a = 16.
774(3) Å, b = 20.
032(3) Å and c = 20.
117(3) Å; overall agreement factor R = 10.
7% for 2014 data with |Fobs| < 3σ(F); resolution 1.
0 Å.
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