Amyloid fibril formation by peptide LYS (11-36) in aqueous trifluoroethanol.
Peptide LYS (11-36), derived from the beta-sheet region of T4 lysozyme, forms an amyloid fibril in aqueous trifluoroethanol (TFE) at elevated temperature. The peptide has a moderate alpha-helix content in 20 and 50% (v/v) TFE solution; large quantities of fibrils were formed after incubation at 55 degrees C for 2 weeks as monitored by a thioflavin T fluorescence assay. No fibrils were observed when the peptide initially existed predominantly as a random coil or as a complete alpha helix. Our results suggest that a moderate amount of alpha helix and random coil present in the peptide initially facilitates the fibril-formation process, but a high alpha-helix content inhibits fibril formation. Transmission electron microscopy revealed several types of fibril morphologies at different TFE concentrations. The fibrils were highly twisted and consisted of interleaved protofilaments in 50% TFE, while smooth and flat ribbonlike fibrils were found in 20% TFE. In 50% TFE, the fibril growth rate of LYS (11-36) was found to depend strongly on peptide concentration and seeding but was insensitive to solution pH and ionic strength.
Liu
Wei
W
Chemical Engineering Department, University of California, Berkeley, 94720, USA.
Prausnitz
John M
JM
Blanch
Harvey W
HW
D000595:Amino Acid Sequence / Q000235:genetics; D016229:Amyloid beta-Peptides / Q000138:chemical synthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D009113:Muramidase / Q000138:chemical synthesis* / Q000235:genetics; D010446:Peptide Fragments / Q000138:chemical synthesis* / Q000235:genetics; D014270:Trifluoroethanol / Q000138:chemical synthesis*; D014867:Water / Q000737:chemistry
D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C108356:T4 lysozyme (11-36); D014867:Water; D014270:Trifluoroethanol; D009113:Muramidase