Figure 8. P1′ substrate specificity profiles of caspase-3, caspase-6, and caspase-7, as determined using two internally quenched fluorogenic substrate libraries containing either Asp or Glu at P1 (ACC-GDEV(D/E)-XKK(DNP)G-NH₂).

The library concentration was 2 μM. The x-axis represents amino acids using the standard three-letter code, and the y-axis shows the substrate hydrolysis rate expressed as RFU/s/10 nM caspase (relative fluorescence units per second per 10 nM of caspase).