Table 2.

Kinetic data of WT ChoE and mutants

Enzyme	Substrate	kcat(app)	Km(app)	KSI(app)	kcat/Km
		s−1	mm		M−1 s−1
WTa	ATCh	200 ± 25	0.10 ± 0.02	0.9 ± 0.2	2.0 × 106
S38A	ATCh	-b	-	-	-
H288N	ATCh	-	-	-	-
D285Nc	ATCh	5.0 ± 0.3	1.6 ± 0.4	-	3.1 × 103
Y106Ac	ATCh	99 ± 4	2.15 ± 0.25	-	4.6 × 104
W287Ac	ATCh	214 ± 9	1.64 ± 0.18	-	1.3 × 105
WTa	PTCh	316 ± 43	0.07 ± 0.02	1.0 ± 0.3	4.5 × 106
S38A	PTCh	-	-	-	-
H288N	PTCh	-	-	-	-
D285Nc	PTCh	6.2 ± 0.2	0.28 ± 0.05	-	2.2 × 104
Y106Ac	PTCh	179 ± 5	1.37 ± 0.11	-	1.3 × 105
W287Ac	PTCh	190 ± 5	1.60 ± 0.13	-	1.2 × 105
WTa	BTCh	6.2 ± 0.2	0.024 ± 0.004	6.2 ± 0.9	2.6 × 105
WTc	pNPA	83 ± 13	0.8 ± 0.3	-	1.0 × 105
WTc	pNPP	439 ± 45	0.35 ± 0.10	-	1.2 × 106
WTc	pNPB	5.8 ± 0.3	0.12 ± 0.01	-	4.8 × 104
WT	pNPO	-	-	-	-
WTa	ATCh + PI	10.2 ± 0.7	0.1 ± 0.02	11.9 ± 4.3	1.0 × 105
WTa	ATCh + TEAC	57.6 ± 1.8	0.06 ± 0.01	175 ± 104	9.6 × 105

^aFit to Equation 1 (Krupka) (21) and “Materials and methods.” Fit to Equation 2 gave identical values.

^bUnmeasurable.

^cFit to Michaelis-Menten equation (Equation 3).