Table 3.

Substrate Specificity of QR1 Enzyme

	Catalytic Rates (Kcat (s−1)]a
	QR1	P1-ZCr, AT-AER	ZCr
Substrate	T. versicolor	(AT5G16970)	Cavia porcellus
PAQ	23.3	98	19
1,2-Napthoquinone	2.44b	54c	39
5-Hydroxy-1,4-napthoquinone (juglone)	0.31	1.9	4.9
DMBQ	0.09	ND	ND
2-Methylnaphthalene-1,4-dione (menadione)	0	0	0
2,3-Dimethoxy-5-methyl-1,4-bezoquinone	0	ND	ND
1,4-Benzoquinone
1,4-Napthoquinone	0	3c	1d
Diamide	0b	95	0

^aK_cat (s⁻¹) values determined from the maximum velocities with 200 μM NADPH and 100 μM acceptor.

^bActivity determined with MTT tetrazolium dye.

^cK_cat (s⁻¹) values determined from the maximum velocities with 50 μM NADPH and 25 μM acceptor.

^dK_cat (s⁻¹) values determined from the maximum velocities with 50 μM NADPH and 250 μM acceptor.

NADPH oxidation rates were measured as change in absorbance at 610. Rate = average of three rate measurements (μmol 0.5 mL⁻¹ min⁻¹). K_cat (s⁻¹) = rate × 10⁻⁶/(7.5 × 10⁻¹²)/60.