Table I. Kinetic parameters of DEVD- and DVKD-based peptide cleavage by caspase-7 and -3.

The catalytic constant (k_cat), the Michaelis-Menten constant (K_m), and the specificity constant (k_cat/K_m) of Ac-DEVD-amc, Ac-XXDVKD-amc, and the internally quenched substrate Abz-QKDVKDGKYSQY(NO₂) by caspase-7 and -3 were determined as described under “Experimental Procedures.”

Substrate	kcat		Km		kcat/Km
	C7	C3	C7	C3	C7	C3
	s−1		μm		m−1 s−1
DEVDa	0.17 ± 0.00	8.32 ± 0.32	9.0 ± 0.6	108 ± 14	18,900 ± 1,280	76,500 ± 10,800
DEVDb	0.14 ± 0.00	8.39 ± 0.47	7.9 ± 0.6	112 ± 11	17,800 ± 1,380	74,700 ± 8,700
DVKDb	0.23 ± 0.01	0.74 ± 0.03	53 ± 6	267 ± 27	4,330 ± 590	2,790 ± 312
ADVKDb	0.11 ± 0.00	0.77 ± 0.03	35 ± 4	243 ± 27	3,080 ± 437	3,180 ± 389
KDVKDb	0.59 ± 0.02	0.79 ± 0.03	133 ± 13	407 ± 36	4,390 ± 494	1,940 ± 188
AKDVKDb	0.63 ± 0.02	0.48 ± 0.01	129 ± 11	439 ± 27	4,840 ± 444	1,100 ± 77
QKDVKDb	0.43 ± 0.02	0.19 ± 0.01	92 ± 12	356 ± 39	4,690 ± 657	560 ± 69
“Quencher”c	0.25 ± 0.02	0.005 ± 0.001	173 ± 27	192 ± 68	1,450 ± 253	26 ± 10

^a Commercial source.

^b Synthesized in house.

^c Abz-QKDVKDGKYSQY(NO₂).