ELISA-detected binding of cross-linked Aα221-610 oligomers, Aα221-610 monomers and fibrinogen to immobilized plasminogen or tPA. 2 μM of cross-linked Aα221-610 oligomers (αC-XL), Aα221-610 monomer (αC-mon), or fibrinogen (Fg) was added to surface-adsorbed plasminogen (panel A) or tPA (panel B). Bound fragments were detected spectrophotometrically at 405 nm using biotinylated avidin conjugated to alkaline phosphatase, as described in Experimental Procedures. All results are means ± the standard deviation of two independent experiments, each performed in duplicate.