Continuous screening of BACE1-inhibiting compounds at a single SPR chip, with each screening cycle encircled by the brackets on top of the Figure. The flow rate and temperature for the BACE1 cleavage were 3 μL/min and 37°C, respectively, while injections of other solutions were made at 20 μL/min at 25°C. In cycles 1, 2, 3, and 4, 10 nM BACE1 was mixed with 120 nM compound 3, 20 nM compound 1, 120 nM compound 1, and 2 μM compound 2, respectively. For clarity, the entire BACE1 injection peak is shown only for cycle 1 and the large imidazole injection peaks are truncated.