Table 1. Kinetic Constants of Native and Engineered Constructs of SaMTAN.

SaMTAN construct	kcat (s–1)	Km (μM)	kcat/Km (M–1 s–1)
native homodimer	10.2 ± 0.1	0.9 ± 0.3	1.13 × 107
F104C/C186S homodimer	7.2 ± 0.4	2.9 ± 1.2	2.48 × 106
native fusion homodimer	8.3 ± 0.2	1.3 ± 0.1	6.38 × 106
E173Q + native fusion heterodimer	2.0 ± 0.2	0.5 ± 0.2	4.0 × 106
E173Q homodimer	<0.1	not measured	not measured