TABLE 3.

AChE activity decay rates influenced by temperature and urea perturbations for wild-type and mutant AChEs

Rate constants ± S.E. are calculated from triplicate experiments. Values in the columns are reported as first-order rate constants and half-times, t₅₀. Significance of the differences between mutant decay rates and wtT547 and between D134H and D134H/R136Q mutants is indicated.

Enzyme	Decay Rate Constant at 52°C	52°C t50 Ratio+	Decay Rate Constant in Urea	Urea t50 Ratio+
	min−1		min−1
wtT547	0.011 ± 0.002	1.0	0.040 ± 0.003	1.0
R3Q	0.024 ± 0.008	0.36*	0.049 ± 0.005	0.82*
H322N	0.022 ± 0.004	0.48**	0.060 ± 0.01	0.63*
D134H	0.30 ± 0.07	0.036***	0.25 ± 0.04	0.17***
D134H/R136Q	0.070 ± 0.02	0.18**††	0.096 ± 0.006	0.42***†††

⁺ t₅₀ mutant/t₅₀ wild type.

^* P > 0.05 (vs. wtT547).

^** P = 0.05 (vs. wtT547).

^*** P < 0.05 (vs. wtT547).

^†† P = 0.05 (vs. D134H).

^††† P < 0.05 (vs. D134H).