TABLE 2.

Kinetic parameters for the reactions of hyperactive ALAS enzymes

Enzymatic reactions were monitored at 20 °C. WT, wild type; NA, not applicable.

Enzyme	Steady state parameters					Presteady state parameters
	kcat	KmGly	KmSCoA	kcat/KmGly	kcat/KmSCoA	Qfa	Qd1b	Qd2c
	s−1	mm	μm	mm−1 · s−1	μm−1 · s−1	s−1	s−1	s−1
WT	0.02 ± 0.01	14 ± 2.0	11 ± 1.0	1.1 × 10−3	1.8 × 10−3	0.8	0.53	0.01
SS2	0.31 ± 0.06	12 ± 1.2	3.0 ± 0.3	0.02	0.10	16	1.7	NA
A4	0.16 ± 0.01	14 ± 1.1	2.3 ± 0.4	0.01	0.07	7.1	1.7	0.07
F3	0.20 ± 0.01	13 ± 1.1	2.6 ± 0.4	0.02	0.08	7.7	1.1	0.17
H1	0.23 ± 0.14	13 ± 1.4	2.0 ± 0.3	0.02	0.11	10	1.5	NA
F10	0.17 ± 0.01	16 ± 1.8	1.1 ± 0.7	0.01	0.15	3.7	0.98	0.15
F1	0.20 ± 0.02	16 ± 1.2	2.9 ± 0.4	0.01	0.07	4.0	1.1	NA
A8	0.07 ± 0.01	25 ± 3.7	2.3 ± 0.4	2.8 × 10−3	0.03	4.8	0.81	0.12
D8	0.03 ± 0.01	24 ± 3.1	1.7 ± 0.7	1.3 × 10−3	0.18	5.4	0.44	0.02
G7	0.07 ± 0.01	15 ± 1.7	1.5 ± 0.1	4.6 × 10−3	0.05	4.4	0.87	0.12

^a Rate for quinonoid intermediate formation.

^b Rate for first step of quinonoid intermediate decay.

^c Rate for second step of quinonoid intermediate decay.