Amyloid beta

Introduction

Alzheimer's disease is characterized by extracellular proteic plaques and intracellular neurofibrillary tangles.^[1] These plaques are collections of fibrils consisting mostly of beta-amyloid of aggregated beta-sheets. The oxidative stress that an affected brain is under is further proof of the toxicity of amyloid beta. When amyloid beta is in contact with metal ions and oxygen reactive oxygen species (especially hydrogen peroxide) are created.^[2] Amyloid beta also maintains the capacity to to induce pore formation in neuronal and endothelial cells which can trigger cell death.^[1][2] The final source of amyloid beta toxicity stems from its ability to induce endothelial cell damage through the production of superoxide, though the mechanism of such induction is unclear.^[2]

Structure

Amyoloid beta is actually the of the which is a type I membrane-spanning glycoprotein [APP].^[2] The most reasonable structure determined structure consists of ; the first helix (residues 8-25) is well defined and has an RMSD of 0.38 angstroms and the second (residues 28-38) is interrupted at the Ile32-Gly33 connection. The two helices are connected by a (residues 26 and 27).^[1]

References

1. ↑ ^{1.0 1.1 1.2} Crescenzi O, Tomaselli S, Guerrini R, Salvadori S, D'Ursi AM, Temussi PA, Picone D. Solution structure of the Alzheimer amyloid beta-peptide (1-42) in an apolar microenvironment. Similarity with a virus fusion domain. Eur J Biochem. 2002 Nov;269(22):5642-8. PMID:12423364
2. ↑ ^{2.0 2.1 2.2 2.3} Rauk A. Why is the amyloid beta peptide of Alzheimer's disease neurotoxic? Dalton Trans. 2008 Mar 14;(10):1273-82. Epub 2008 Feb 12. PMID:18305836 doi:10.1039/b718601k