Fremont, CA – October 19, 2009 The hallmark of Alzheimer’s disease (AD) pathology includes beta-sheet aggregates of beta-amyloid peptides in senile plaques and hyperphosphorylated tau protein in neurofibrillary tangles (NFT).1-2 Recent publications have reported the use of Cys-containing mutants as models for aggregation studies.3-5 Shivaprasad and Wetzel employ “the use of disulfide bond cross-linking to probe the fold within the core and the packing interactions between beta-sheets.” Among the Cys mutants they studied is the S26C (Ser substituted with Cys at position 26).3 Upon oxidation of the S26C monomer, cysteines are capable of forming intermolecular disulfide bond creating the S26C dimer.3-4 Using this synthetic dimer, Hu, et al. show that it behaves similarly to beta-amyloid dimer-containing human CSF, suggesting that A-beta dimers may be the earliest synaptic disrupting species in AD.4
The supplier of the world’s largest collection of beta-amyloid GO™ (catalog) Peptides, AnaSpec has added the following amyloid peptides to its selection: beta-amyloid (1-40) S26C; beta-amyloid (1-42) S26C dimer;? beta-amyloid (1-42) S26C? and other Cys-containing? beta-?amyloid peptides (Cys on the N or C-terminus as well as in the internal sequence).
Besides using these Cys-containing beta-amyloid peptides for dimerization, the availability of the Cysteine’s thiol group also allows researchers the flexibility of reacting these peptides with any maleimide containing fluorescent dyes or biomolecules. For example, the thiol group of Cys-beta-amyloid (1-40) can react with HiLyte Fluor™ 488, C2 maleimide to form HiLyte Fluor™ 488-Cys-beta-amyloid (1-40) [Cys(HiLyte Fluor™ 488)-DAEFRHDSGYEVHHQKLVFFAEDVGSNKGAIIGLMVGGVV].
References:
1. Khachaturian, ZS. Arch. Neurol. 42, 1097 (1985).
2. Mirra, SS. et al. Neurol. 41, 479 (1991).
3. Shivaprasad, S. and R. Wetzel. J. Biol. Chem. 281, 993 (2006).
4. Hu, N-W. et al. Brain doi:10.1093/brain/awn174.
5. Shankar, GM. et al. Nat. Med. 14, 837 (2008).
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