Beta-helical fibrils from a model peptide.
A synthetic peptide, KLEG13 (Ac-KLKLKLELELELG-NH2), composed of alternating bulky hydrophilic and hydrophobic amino acid residues formed clear, viscous dispersions of fibrils in saline solutions. The fibrils had a uniform diameter of 2 nm as measured on electron micrographs of negatively stained preparations. 13C solid-state nuclear magnetic resonance spectroscopy of the fibrils indicated the presence of a beta-conformation. Circular dichroic spectra of the dispersion of fibrils were essentially identical to the calculated spectrum of a 100% beta-helix. Space-filling CPK models of a proposed beta-helical conformation of the peptide, in which the leucine side chains form a hydrophobic core and the hydrophilic lysine and glutamate side chains extend outwards from the helix, had a diameter consistent with the observed 2-nm diameter of the fibrils. This study may have implications regarding the structure of amyloid fibrils.
Lazo
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ND
Department of Dermatology, The University of Iowa College of Medicine, Iowa City 52242, USA. nlazo@blue.weeg.uiowa.edu
Downing
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DT
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D009682:Magnetic Resonance Spectroscopy; D008854:Microscopy, Electron; D008958:Models, Molecular; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D017433:Protein Structure, Secondary
C106799:KLEG13 peptide; D009842:Oligopeptides