Revealing two important tryptophan residues with completely different roles in a dye-decolorizing peroxidase from Irpex lacteus F17

Table 4 Steady-state kinetic constants (K_m (μM), k_cat (s ⁻¹), k_cat/K_m (M⁻¹ s⁻¹)) for the reduction of H₂O₂ and the oxidation of ABTS, DMP and RB 19 by Il-DyP4 and the variants W380Y

	Kinetic constants^a	H₂O₂	ABTS	DMP	RB19
Il-DyP4^c	K_m	84.48 ± 20.57	67.29 ± 13.05	8.98 ± 1.02	139.87 ± 42.80
	k_cat	1025.00 ± 37.94	790.00 ± 56.06	58.99 ± 0.45	187.9 ± 37
	k_cat/K_m	(1.21 ± 0.18) × 10⁷	(1.17 ± 0.43) × 10⁷	(6.57 ± 0.44) × 10⁶	(1.34 ± 0.86) × 10⁶
W380Y^c	K_m	20.08 ± 3.35	275.07 ± 77.79	–^b	–^b
	k_cat	165.65 ± 8.28	88.38 ± 15.66	–^b	–^b
	k_cat/K_m	(8.25 ± 2.47) × 10⁶	(3.21 ± 2.01) × 10⁵	–^b	–^b

^aAll data were fitted using the hyperbola function by Origin
^bNot calculated because of a lack of activity
^cSubstrate oxidation was measured at pH 3.5 (10 mM sodium tartrate buffer) using 3.3 nM of enzyme concentration obtained from a molar extinction coefficient

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