Effect of Metal Chelators on γ-Secretase Indicates That Calcium and Magnesium Ions Facilitate Cleavage of Alzheimer Amyloid Precursor Substrate
Figure 3
Effect of EDTA and phenanthroline on γ-secretase activity. (a) Guinea pig γ-secretase activity was assayed on C100-3XFLAG in alternate buffer conditions (2 mM EDTA or 3 mM CaCl2 and 3 mM MgCl2). (b) Quantitative analysis of five separate experiments shows AICD production in the presence of EDTA was 28% of that produced in the presence of CaCl2, and MgCl2. (c) Quantitative analysis of Aβ40 by sandwich DELFIA shows that Aβ production in the presence of EDTA is lower than in the presence of CaCl2, and MgCl2. (d) γ-Secretase activity extracted from SH-SY5Y membranes was assayed in buffer conditions as indicated. Phenanthroline (Pht) concentration was 5 mM. L-685,458 was 0.5 μM. (e) Quantitative analysis of three blots corresponding to assays carried out as in (d) The error bars represent SEM.
