Biodegradation of p-nitrophenol by Rhodococcus sp. 21391 unveils a two-component p-nitrophenol monooxygenase with broad substrate specificity

Table 1 Kinetic parameters of RsNpcB

Substrate	K_m (μM)	k_cat (s⁻¹)	k_cat/ K_m × 10⁶ (M⁻¹ s⁻¹)
NADH^a + FAD	0.11 ± 0.02	4.36 ± 1.4	40.20 ± 3.8
NADH^a + FMN	0.02 ± 0.007	1.08 ± 0.094	49.63 ± 1.007
NADH + FAD^b	45.47 ± 10.78	2.60 ± 1.03	0.058 ± 0.004
NADPH + FAD^b	16.44 ± 4.62	1.83 ± 0.67	0.12 ± 0.008

Enzymatic analyses of RsNpcB were conducted in 50 mM Tris–HCl buffer (pH 7.5) at 25 °C
NADH dihydronicotinamide adenine dinucleotide, NADPH dihydronicotinamide-adenine dinucleotide phosphate, FAD flavin adenine dinucleotide, FMN flavin mononucleotide
^a Concentration of NADH in the reaction was kept constant at 200 μM with FAD or FMN varying from 0.2–1.0 μM
^b Concentration of FAD in the reaction was kept constant at 20 μM with NADH or NADPH varying from 20–220 μM

ISSN: 1475-2859