Table 3. Kinetic parameters of six internally quenched substrates (ACC-GDEV(D/E)-XKK(DNP)G-NH₂) measured for caspase-3 and caspase-7.

Substrate	Caspase-3				Caspase-7
	kcat, s−1	KM, μM	kcat/KM, M−1s−1	kcat/KM, E/D ratio	kcat, s−1	KM, μM	kcat/KM, M−1s−1	kcat/KM, E/D ratio
DEVD/G	5.16	3.17	1629000	—	0.926	4.80	193600	—
DEVD/A	4.69	4.21	1930500	—	1.04	6.29	193590	—
DEVD/S	6.52	4.40	1489800	—	0.795	6.38	124700	—
DEVE/G	0.665	3.77	176700	0.11	0.475	7.32	65100	0.34
DEVE/A	0.357	15.98	22360	0.012	0.0162	16.52	958	0.005
DEVE/S	0.0646	7.30	8950	0.006	0.0032	10.36	307	0.0025

The enzyme concentrations varied from 1 to 100 nM depending on the substrate, as described in the Methods section.