Lysine as helix C-capping residue in a synthetic peptide.
The structure of the synthetic peptide CH3CO(Leu-Ser-Leu-Leu-Leu-Ser-Leu)3Lys-NH2 in trifluoroethanol/water 60/40 (volume ratio) was characterized by two-dimensional nmr spectroscopy. The peptide, closely related to the amphiphilic helix models designed by W. F. De-Grado and co-workers to mimic protein ion channels [(1988) Science, Vol. 240, p. 1177-1181], folds into a regular helix spanning residues 1-20. Evidence for a helix C-terminal capping conformation, involving the terminal lysine residue, was observed from Overhauser effects and checked for consistency by restrained molecular dynamics simulations. The side-chain amino group of Lys22 forms a hydrogen bond with the carbonyl of Leu18, and the distorted helical geometry of the terminal dipeptide allows the inclusion of a water bridge between the backbone NH of the Lys22 residue and the carbonyls of Leu19 and Ser20.
Esposito
G
G
Institut de Chimie Organique Université de Lausanne, Switzerland.
Dhanapal
B
B
Dumy
P
P
Varma
V
V
Mutter
M
M
Bodenhausen
G
G
D000595:Amino Acid Sequence; D008239:Lysine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry*; D017433:Protein Structure, Secondary
D009842:Oligopeptides; D008239:Lysine