Table 2.

Steady-state kinetic constants for AANATL2 mutant enzymes^a

Mutant b	Acetyl-CoA
	Km, app (μM)	kcat, app (s−1)	(kcat/Km)app (M−1s−1)	$\frac{{\left(\frac{k_{\mathit{cat}}}{K_m}\right)}_{\mathit{app}-\mathit{mutant}}}{{\left(\frac{k_{\mathit{cat}}}{K_m}\right)}_{\mathit{app}-\mathit{wild}-\mathit{type}}}\times 100$
				%
Wild-type	5 ± 1	1.6 ± 0.1	(3.1 ± 0.4) × 105	100
E29A	5.1 ± 0.2	0.37 ± 0.01	(7.2 ± 0.3) × 104	23
P30A	3.3 ± 0.4	0.032 ± 0.001	(10 ± 1) × 103	3.2
R138A	1.6 ± 0.1	0.313 ± 0.004	(1.9 ± 0.1) × 105	61
S167A	40 ± 2	0.75 ± 0.01	(1.9 ± 0.1) × 104	6.1
S171A	ndc	ndc	ndc	ndc
H206A	ndc	ndc	ndc	ndc
Mutant d	Tyramine
	Km, app (μM)	kcat, app (s−1)	(kcat/Km)app (M−1s−1)	$\frac{{\left(\frac{k_{\mathit{cat}}}{K_m}\right)}_{\mathit{app}-\mathit{mutant}}}{{\left(\frac{k_{\mathit{cat}}}{K_m}\right)}_{\mathit{app}-\mathit{wild}-\mathit{type}}}\times 100$
				%
Wild-type	5 ± 1	1.47 ± 0.03	(2.9 ± 0.3) × 105	100
E29A	85 ± 5	0.37 ± 0.01	(4.4 ± 0.3) × 103	1.5
P30A	52 ± 7	0.043 ± 0.001	820 ± 110	0.28
R138A	6 ± 1	0.26 ± 0.01	(4.5 ± 0.7) × 104	16
S167A	19 ± 2	1.03 ± 0.04	(5.3 ± 0.7) × 104	18
S171A	ndc	ndc	ndc	ndc
H206A	ndc	ndc	ndc	ndc

^aKinetic constants are reported as ± standard error (n = 3).

^bThe reaction rate was measured at a fixed saturating concentration of tyramine while varying the concentration of acetyl-CoA.

^cThe notation of “nd” is used for a mutant that did not display a rate of coenzyme A release at 412 nm above the baseline hydrolysis rate.

^dThe reaction rate was measured at a fixed saturating concentration of acetyl-CoA while varying the concentration of tyramine.