Premium
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
Author(s) -
Karle Isabella L.,
FlippenAnderson Judith L.,
Sukumar M.,
Balaram P.
Publication year - 1992
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/prot.340120404
Subject(s) - antiparallel (mathematics) , hydrogen bond , peptide , chemistry , helix (gastropod) , crystallography , molecule , stereochemistry , leucine , side chain , amino acid , alpha helix , crystal structure , circular dichroism , organic chemistry , physics , biochemistry , biology , ecology , quantum mechanics , snail , magnetic field , polymer
The 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 C 56 H 102 N 10 O 13 , crystallizes in space group P2 1 2 1 2 1 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 |F obs | < 3σ(F); resolution 1.0 Å.