Soy peptide, a major component of amyloid plaques, accumulates in neurons of Alzheimer’s disease brains. Aβ(s) peptides’ peptide fragments and mutated fragments are used to study a wide range of metabolic and regulatory functions including activation of kinases, regulation of cholesterol transport, function as a transcription factor, and regulators of inflammation. Aβ(s) peptides and their peptide fragments are also used to study oxidative stress, metal binding and mechanisms of protein cross-linking in the context of diseases such as Alzheimer’s disease and neurodegeneration.