The amino acid sequence of Aβ(25-35) peptide is NH 2 -Gly-Ser-Asn-Lys-Gly-Ala-Ile-Ile-Gly-Leu-Met-COOH, where the first Gly represents the amino acid 25 and the last Met represents the amino acid 35. Amyloid beta-peptide(25-35) is also investigated in gel state for the first time. Comparative studies are also carried out using vibrational absorption and ECD. The conformational preference of Aβ(25-35) peptide film is also investigated using vibrational absorption and VCD spectroscopy. Amyloid beta-peptide(25-35) induces apoptotic effects on isolated brain mitochondria and the redox state of methionine-35, plays a key role in the induction of programmed cellular death pathways and toxic events. β-Amyloid Aggregation Guidelines (Following is our recommended protocol. This protocol only provides a guideline, and should be modified according to your specific needs). 1. Solid Aβ peptide was dissolved in cold hexafluoro-2-propanol (HFIP). The peptide was incubated at room temperature for at least 1h to establish monomerization and randomization of structure. 2. The HFIP was removed by evaporation, and the resulting peptide was stored as a film at -20 or -80 ℃. 3. The resulting film was dissolved in anhydrous DMSO at 5 mM and then diluted into the appropriate concentration and buffer (serum- and phenol red-free culture medium) with vortexing. 4. Next, the solution was age 48h at 4-8 ℃. The sample was then centrifuged at 14000g for 10 min at 4-8 ℃; the soluble oligomers were in the supernatant. The supernatant was diluted 10-200-fold for experiments. Methods vary depends on the downstream applications.
Rats are injected with Aβ25–35 peptide intracerebroventricularly and compound Danshen (CDS) are subsequently administered once daily for 23 days. Rats’ behavior is monitored using Morris water maze and passive avoidance. Real time PCR and Western blotting are used in determining amyloid precursor protein (APP), β-site APP cleaved enzyme-1(BACE1), Presenilin-1 (PS1), Insulin-degrading enzyme (IDE) and neprilysin (NEP) in hippocampus. The Alzheimer' s disease (AD) model group present with spatial learning and memory impairments. CDS and donepezil administration significantly ameliorate the Aβ25–35 peptide-induced memory impairment in both Morris water maze (P [3] .