Table 2. In vitro Enzymatic Assays Performed with rhIDO (37 °C, pH 6.5).

substrate	Km	kcat/Kma
l-Trp (11)	15 ± 2 μMb	2100.102 M–1 s–1b
1-Me-l-Trp (12)	62 ± 9 μMb	(38 ± 17).102 M–1 s–1
5-HO-l-Trp (13)	17 ± 1.1 μMc	(21 ± 4).102 M–1 s–1
1-FETrp (5)d	70 ± 30 μMe	(5.8 ± 0.7).102 M–1 s–1

^aRatios determined by measurement of the substrate concentration in relation to the incubation time (method B).

^bValues determined by Lu et al.³⁰

^cValues determined by Basran et al.²⁹

^dRacemate.

^eConstant obtained by initial-rate determination (method B).