Table I.

Comparison of Steady-State Kinetic Constants for Wild-type ALAS, R85K, R85L, and R85L/T430V with CoA Derivatives as Substrates

Parameter	Wild-type ALAS	R85K	R85L	R85L/T430V
	Succinyl-CoA as a substrate
kcat, min−1	10.0 ± 0.2	6.4 ± 0.2	0.94 ± 0.10	0.11 ± 0.03
, μM	2.9 ± 0.1	12.4 ± 0.6	20.3 ± 1.0	9.6 ± 0.8
kcat/, min−1 μM−1	3.6 ± 0.2	0.53 ± 0.04	0.050 ± 0.003	0.010 ± 0.002
, mM	24.2 ± 0.4	20.0 ± 0.4	63.1 ± 2.2	98.4 ± 3.5
kcat/, min−1 mM−1	0.43 ± 0.04	0.32 ± 0.06	0.010 ± 0.002	0.001 ± 0.002
	Octanoyl-CoA as a substrate
kcat, min−1	3.4 ± 0.2	10.3 ± 0.4	1.8 ± 0.3	(1.0 ± 0.1) × 10−3
, μM	0.51 ± 0.04	1.5 ± 0.04	0.55 ± 0.03	17.2 ± 0.6
kcat/, min−1 μM−1	6.8 ± 0.8	7.0 ± 0.2	3.3 ± 0.1	(5.6 ± 0.2) × 10−5
, mM	17.1 ± 0.9	25.2 ± 1.1	55.2 ± 5.0	74.2 ± 3.3
kcat/, min−1 mM−1	0.14 ± 0.01	0.52 ± 0.02	0.030 ± 0.005	(1.0 ± 0.08) × 10−5
	Butyryl-CoA as a Substrate
kcat, min−1	6.3 ± 0.3	10.2 ± 0.3	2.01 ± 0.08	0.060 ± 0.002
, μM	6.1 ± 0.09	2.7 ± 0.1	9.3 ± 1.0	0.54 ± 0.03
kcat/, min−1 μM−1	1.0 ± 0.1	3.7 ± 0.4	0.21 ± 0.04	0.03 ± 0.002
, mM	29.3 ± 4.6	17.2 ± 0.7	70.3 ± 6.6	88.2 ± 3.9
kcat/, min−1 mM−1	0.26 ± 0.03	0.50 ± 0.01	0.030 ± 0.005	(6.1 ± 0.8) × 10−4
	β-Hydroxybutyryl-CoA as a Substrate
kcat, min−1	4.0 ± 0.8	2.8 ± 0.1	0.65 ± 0.03	(1.0 ± 0.2) × 10−4
, μM	9.8 ± 1.0	5.5 ± 0.2	6.1 ± 0.8	74.2 ± 0.6
kcat/, min−1 μM−1	0.41 ± 0.04	0.51 ± 0.04	0.11 ± 0.02	(1.3 ± 0.4) × 10−6
, mM	22.1 ± 0.8	18.2 ± 3.2	59.1 ± 4.7	92.2 ± 6.0
kcat/, min−1 mM−1	0.17 ± 0.06	0.14 ± 0.03	0.011 ± 0.003	(1.0 ± 0.3) × 10−6
	Glutaryl-CoA as a Substrate
kcat, min−1	7.0 ± 0.4	0.30 ± 0.03	2.2 ± 0.1	n/d
, μM	17.0 ± 1.6	7.5 ± 0.6	30.1 ± 1.1	n/d
kcat/, min−1 μM−1	0.41 ± 0.05	0.04 ± 0.003	0.07 ± 0.006	n/d
, mM	28.4 ± 0.8	21.2 ± 0.2	70.6 ± 4.2	n/d
kcat/, min−1 mM−1	0.29 ± 0.02	0.010 ± 0.002	(8.0 ± 0.7) × 10−4	n/d

n/d, not determined.