I read a paper by Ross and Poirier [1, p. S12] which has the following lines (see section Commonalities of amyloid structure) that describe the structure of protein in a fibril:
The most extensively characterized amyloid fibril is that formed from the β-amyloid (Aβ) peptide implicated in AD. Using SOLID-STATE NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY, the in-register, parallel β-sheet organization of fibrils formed by Aβ10–35, a fragment of the full-length 42-residue Aβ peptide, was first described.
I couldn't understand what "in-register, parallel β-sheet" means.
- Ross, C. A.; Poirier, M. A. Protein Aggregation and Neurodegenerative Disease. Nat Med 2004, 10 (7), S10–S17. https://doi.org/10/dppb95.