Table 1. Kinetic parameters for iodination and bromination reactions catalyzed by VirX1 with selected substrates.

The values for iodination (light purple columns) and bromination (light orange columns) reactions were determined by non-linear regression using Origin. All assays were performed in 200 μl total volume containing VirX1 (1 μM), an excess of the partner flavin reductase PrnF (10 μM), NADH (2.5 mM), NaBr/NaI (10 mM), FAD (10 μM) in phosphate buffer (50 mM, pH 7.4) and varied concentrations of substrate resuspended in DMSO and incubated at 28 °C. ND denotes not determined.

Compound	NaI			NaBr
	kcat (min-1)	Km (μM)	kcatKm (min-1 μM)	kcat (min-1)	Km (μM)	kcat/Km (min-1 μM)
1	5.0 ± 0.5	28 ± 2	0.179 ± 0.004	2.4 ± 0.6	53 ± 3	0.044 ± 0.008
2	3.1 ± 0.5	145 ± 9	0.021 ± 0.004	1.0 ± 0.1	201 ± 6	0.004 ± 0.001
3	1.3 ± 0.2	190 ± 6	0.006 ± 0.001	ND	ND	ND
4	4.4 ± 0.2	23 ± 2	0.193 ± 0.003	2.9 ± 0.5	31 ± 4	0.093 ± 0.002
5	3.3 ± 0.1	35 ± 1	0.094 ± 0.002	2.2 ± 0.2	33 ± 9	0.066 ± 0.004
6	3.5 ± 0.3	241 ± 4	0.014 ± 0.003	1.9 ± 0.1	310 ± 9	0.006 ± 0.001
7	1.5 ± 0.1	157 ± 3	0.009 ± 0.002	1.7 ± 0.2	227 ± 4	0.007 ± 0.003
8	3.0 ± 0.1	258 ± 7	0.011 ± 0.001	2.2 ± 0.2	254 ± 2	0.008 ± 0.002
10	3.4 ± 0.2	238 ± 13	0.014 ± 0.006	2.1 ± 0.3	282 ± 2	0.007 ± 0.003
11	1.6 ± 0.2	181 ± 6	0.008 ± 0.002	ND	ND	ND
12	2.9 ± 0.3	338 ± 18	0.008 ± 0.002	ND	ND	ND
14	2.2 ± 0.4	135 ± 12	0.016 ± 0.005	1.4 ± 0.1	240 ± 11	0.005 ± 0.001