Environmental Factors Preceding A40 Monomer to Oligomers and the Detection of Oligomers in Alzheimer's Disease Patient Serum
Figure 2
Reactivity patterns of antibodies differ after pH-modification of the Aβ40 peptide [11]. The pH-modified Aβ40 peptides (4 μg/mL) at various pH values were tested for monoclonal antibody (e.g., anti-1–7 (fuchsia diamond), anti-5–10 (green square), 6F/3D (yellow circle), and 4G8 (red triangle)) and anti-1–42 (blue circle) which is a polyclonal antibody, binding at a concentration of 1 μg/mL on the standard ELISA system. Absorbance was measured at 405 nm. Results are expressed as means ± SEM (). The anti-1–7 and anti-5–10 antibodies showed very similar reactivity towards Aβ40 incubated at various pH values, the reactivity remaining constant over the entire pH range. In constant, the 6F/3D antibody showed decreasing reactivity as the pH was lowered from pH 8.0 to 4.6, followed by a dramatic increase as the pH was lowered from pH 4.6 to 3.0. Interestingly, reactivity of the 4G8 antibody showed a profile similar to that shown by antibody 6F/3D, with the lowest signal at pH 4.6.
