Table 1.

Measured kinetic parameters for the hPAH and C29S catalyzed production of Tyr from Phe

Experiments were performed with 75 μm BH₄ at 25 °C, without and with a 1-min preincubation with Phe. Kinetic data were fitted to the Hill equation using SigmaPlot and reporting standard errors.

Enzyme or condition	KM for Phe		Hill coefficient		Vmax		Fold activation
	μm		h		nmol of Tyr·min−1·mg−1
Phe preincubation	−	+	−	+	−	+	(Vmax+Phe ÷ Vmax−Phe)
hPAHa,b	303 ± 54	144 ± 10	1.1 ± 0.1	2.4 ± 0.3	1749 ± 140	5179 ± 1	3.0
C29Sc,d	217 ± 8	180 ± 4	1.9 ± 0.1	2.6 ± 0.1	837 ± 17	4077 ± 6	4.9
C29Sb,e	391 ± 45	153 ± 10	1.7 ± 0.2	2.5 ± 0.3	1367 ± 101	6919 ± 209	5.1

^a Data were on PAH cleaved from a His₆–SUMO construct and affinity-purified with Tris buffers.

^b [Phe] was at 10, 50, 100, 200, 300, 600, 800, and 1,000 μm.

^c Native protein was purified using the Shiman method (17).

^d [Phe] was at 10, 50, 100, 200, 300, and 1,000 μm.

^e Data were on PAH cleaved from a His₆–TEV construct, affinity purified with Tris buffers.