Table 1.

Kinetic Properties of Human PPT and Selected Active-Site Mutants

PPT	Varied Ligand	Km (mM)	kcat (min−1)	kcat/Km (min−1 mM−1)
WT	Mg2+	0.44 ± 0.04	14.4 ± 0.4	32.7
D129A		4.6 ± 0.3	0.0042 ± 0.0005	0.001
H111A		34.5 ± 5.6	7.3 ± 0.6	0.21
R47A		3.3 ± 1.0	48.0 ± 6.6	14.5
R86A		15 ± 3	72.0 ± 5.9	4.8
K185A		1.1 ± 0.1	0.018 ± 0.0004	0.016
E181A		18.3 ± 0.7	0.023 ± 0.0007	0.001
E181Q		7.6 ± 4.6	0.039 ± 0.005	0.005
Q112E		0.75 ± 0.24	1.32 ± 0.21	1.76
E181Q, Q112E		104.1 ± 51	0.019 ± 0.004	0.0002
WT	C2-CoA	0.0249 ± 0.003	14.4 ± 0.73	578
D129A		0.142 ± 0.035	0.0059 ± 0.0001	0.04
H111A		0.095 ± 0.033	6.1 ± 1.3	64.2
R47A		0.076 ± 0.0038	34.0 ± 1.2	447
R86A		0.399 ± 0.041	58.4 ± 3.8	146
K185A		0.0247 ± 0.0036	0.015 ± 0.0004	0.6
E181A		0.0454 ± 0.0038	0.043 ± 0.0015	0.9
E181Q		0.081 ± 0.0013	0.044 ± 0.0026	0.5
Q112E		0.047 ± 0.023	2.2 ± 0.73	46.8
E181Q, Q112E		0.093 ± 0.001	0.024 ± 0.004	0.2

Kinetic parameters for Mg²⁺ were determined at saturating concentrations of acetyl-CoA and vice versa.