The
ß sheet (also
ß-pleated sheet) is the second form of regular
secondary structure in
proteins. Beta sheets consist of
beta strands connected laterally by at least two or three backbone
hydrogen bonds, forming a generally twisted, pleated sheet. A beta strand (also
ß strand) is a stretch of
polypeptide chain typically 3 to 10
amino acids long with backbone in an extended conformation. The higher-level association of ß sheets has been implicated in formation of the protein aggregates and fibrils observed in many human diseases, notably the
amyloidoses such as
Alzheimer's disease.