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Publication Abstract from PubMed

A macrocyclic beta-sheet peptide containing two nonapeptide segments based on Abeta15-23 (QKLVFFAED) forms fibril-like assemblies of oligomers in the solid state. The X-ray crystallographic structure of macrocyclic beta-sheet peptide 3 was determined at 1.75 A resolution. The macrocycle forms hydrogen-bonded dimers, which further assemble along the fibril axis in a fashion resembling a herringbone pattern. The extended beta-sheet comprising the dimers is laminated against a second layer of dimers through hydrophobic interactions to form a fibril-like assembly that runs the length of the crystal lattice. The second layer is offset by one monomer subunit, so that the fibril-like assembly is composed of partially overlapping dimers, rather than discrete tetramers. In aqueous solution, macrocyclic beta-sheet 3, and homologues 4 and 5, form discrete tetramers, rather than extended fibril-like assemblies. The fibril-like assemblies of oligomers formed in the solid state by macrocyclic beta-sheet 3 represent a new mode of supramolecular assembly not previously observed for the amyloidogenic central region of Abeta. The structures observed at atomic resolution for this peptide model system may offer insights into the structures of oligomers and oligomer assemblies formed by full-length Abeta and may provide a window into the propagation and replication of amyloid oligomers.

A Fibril-like Assembly of Oligomers of a Peptide Derived from beta-Amyloid.,Pham JD, Spencer RK, Chen KH, Nowick JS J Am Chem Soc. 2014 Jul 28. PMID:25068693^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.