Table 1.

Experimental and theoretical kinetic isotope effects

Peptide substrates		Experimental KIEs*†		Theoretical structures and KIE predictions
Heavy	Light	Native	I84V	8	9	10	11	12	13
Ac-SQN[1-14C]F‡PVV-NH2	[]Ac-SQNF‡PVV-NH2	1.029(3)	1.025(5)	1.073	1.017	1.020	1.019	1.057	1.025
[]Ac-SQNF‡[15N]PVV-NH2	[14C]Ac-SQNF‡PVV-NH2	0.987(3)	0.989(3)	1.000	1.002	0.996	0.992	1.015	0.995
[]Ac-SQN[18O]F‡PVV-NH2	[14C]Ac-SQNF‡PVV-NH2	0.993(3)	0.999(3)	0.991	0.995	0.994	0.994	0.996	0.995
Ac-SQN[α-3H]F‡PVV-NH2	[14C]Ac-SQNF‡PVV-NH2	0.968(1)	0.976(1)	0.938	0.922	0.919	0.908	0.874	0.917

KIE, kinetic isotope effect.

^*Experimental errors are shown in parentheses (x10^-3) following the KIE values and reflect the standard error of the mean resulting from n ≥ 18 independent measurements.

^†KIEs obtained using the []-Ac remote radiolabel are corrected for a ³H effect that was measured to be 0.974(2) and 0.976(2) for the native and I84V enzyme, respectively.

^‡Denotes the location of the scissile bond.