Harnessing over a decade's worth of experience and a multi-level technology platform that includes peptides, antibodies, dyes and assay kits, AnaSpec, EGT Group is one of the world's most trusted sources of integrated proteomic solutions specifically designed for Alzheimer's Disease research.

Our large collection of ß-Amyloid (1-42) peptides includes:

Native sequences – human and mouse/rat sequences (unless otherwise specified, sequences are human in origin)
Single or multiple amino acid substitution sequences, e.g. S26C
Biotin labeled sequences – N or C terminally labeled, with or without linker
Dye labeled sequences – HiLyte Fluor™ or classic dye labeled
ClearPoint™ heavy-isotope labeled sequences
Shorter sequences that end on the 42^nd amino acid and analog
HFIP treated β-Amyloid (1-42)

ß-Amyloid (Aß) peptides are generated as cleavage products 39 to 43 amino acids in length from the membrane protein, Amyloid Precursor Protein (APP) by two proteases, β-secretase and γ-secretase.^1-3 While only a small amount is processed by β-Secretase, also known as BACE1 (β-secretase APP cleaving enzyme) or memapsin, APP is predominantly processed by α-Secretase, producing a 83-amino acid C-terminal fragment, C83. Subsequent cleavage of C83 by γ-secretase produces a non-toxic N-terminal 3kD protein.^1-2

Aßs are amphiphilic peptides with a hydrophilic N-terminal domain (residues 1 to 28) and a hydrophobic C-terminal (residues 29 to 40-42), the latter corresponding to a part of the transmembrane domain of APP.⁴ β-Amyloid assembly into fibrils is initiated by a conformational transition from random coil to β-sheet (hence the name β-amyloid) and a nucleation-dependent aggregation process.⁴ Aβ peptides that are 39 to 42 amino acid residues in length with a molecular mass of approximately 4 kDa are the core components of neuritic plaques seen in Alzheimer’s disease (AD) brains. The presence of excess amount of Aß deposits and neurofibrillary tangles, NFTs, ^5-6 comprising of hyperphosphorylated Tau proteins are the hallmarks of an AD brain.¹

Aβ (1-42), a major component of amyloid plaques, accumulates in neurons of Alzheimer’s disease (AD) brains. Biochemical analysis of the amyloid peptides isolated from AD brain indicates that Aβ (1-42) is the principal species associated with senile plaque amyloids, while Aβ (1-40) is more abundant in cerebrovascular amyloid deposit.^7-8

Figure 1. A schematic diagram of the amyloid precursor protein (APP) and the cleavage sites of α, β and γ-secretases (diagram modified from Wikipedia: The free encyclopedia. (2008, Mar 12). FL: Wikimedia Foundation, Inc. Retrieved March 12, 2008, from http://en.wikipedia.org/wiki/Image:APP_cleavage.png).

Figure 2. Comparison of the human and mouse/rat b-amyloid (1-42) sequences.

Table 1. A listing of ß-amyloid (1-42) and related peptides. Shaded row denotes that the peptide sequence is of mouse/rat origin (unless otherwise specified, all Aß peptides are of human origin).

Figure 3. Emission spectra of four of the fluorescent dye-labeled β-amyloid (1-42) peptides.

Table 2. Examples of dye-labeled β-amyloid (1-42) peptides.

References:

1. Selkoe DJ. Nature 399, A23 (1999).
2. Suh, Y-H. and F. Checler, Pharmacol Rev 54, 469 (2002).
3. Kang, J. et al. Nature 325, 733 (1987).
4. Jarrett, JT. et al. Biochem 32, 4693 (1993).
5. Masters, CL. et al. EMBO J 4, 2757 (1985).
6. Braak, H. et al. Acta Neuropathol 87, 554 (1994).
7. Nagele, R. et al. Neurosci 110, 199 (2002).
8. Garzon-Rodriguez, W. et al. J Biol Chem 272, 21037 (1997).