Table 1.

Michaelis–Menten kinetic parameters for 2-aryl substituted hydroxybenzothiazoles

	SULT1E1			SULT1A1*1
	Km	Vmax	Vmax/Km	Km	Vmax	Vmax/Km
2a	0.99 ± 0.03	3.18 ± 0.87	3.22 ± 0.9	0.018 ± 0.006	4.97 ± 0.57	275 ± 97
2b	1.42 ± 0.12	1.99 ± 0.07	1.40 ± 0.13	*	*	*
2c	1.42 ± 0.32	2.18 ± 0.08	1.54 ± 0.35	*	*	*
2d	2.11 ± 0.20	2.88 ± 0.14	1.36 ± 0.15	*	*	*
2e	1.00 ± 0.06	1.98 ± 0.05	1.97 ± 0.08	*	*	*
2f	0.90 ± 0.11	1.97 ± 0.08	2.19 ± 0.26	*	*	*
2g	2.36 ± 0.14	2.04 ± 0.04	0.87 ± 0.05	0.025 ± 0.005	0.88 ± 0.05	36 ± 7
2h	0.56 ± 0.09	4.08 ± 0.25	7.29 ± 1.25	0.029 ± 0.008	0.91 ± 0.09	31 ± 9
2i	0.52 ± 0.05	2.95 ± 0.08	5.64 ± 0.56	0.01 ± 0.003	0.67 ± 0.05	67 ± 21
2j	0.25 ± 0.02	4.33 ± 0.12	17.1 ± 1.4	*	*	*
2k	1.32 ± 0.08	3.57 ± 0.06	2.69 ± 0.16	*	*	*
2l	0.12 ± 0.02	3.33 ± 0.19	27.75 ± 4.89	0.058 ± 0.019	1.24 ± 0.09	21 ± 7
2m	0.77 ± 0.08	1.74 ± 0.05	2.26 ± 0.24	†	†	†
2n	0.43 ± 0.10	1.05 ± 0.08	2.44 ± 0.60	†	†	†

SULT1A1*2 assay with compound 2a yielded K_m = 0.045 ± 0.01 and V_max = 5.25 ± 0.55 (V_max/K_m 117 ± 23); sulfate formation was seen for compounds 2m and 2n, however, kinetic parameters could not be reliably measured. All 2-aryl substituted hydroxybenzothiazoles were assayed against SULT1A3 and SULT2A1 with no detectable activity. Compound 2b was additionally assayed against the SULT1B1 enzyme from 20 nM to 3 μM with no detectable activity. All experiments were performed in triplicate and all values are expressed as mean ± s.d. Units: K_m as μM, V_max as nmol/ min /mg, andV_max/K_m as (nmol/ min /mg)/μM.

^*No detectable activity.

^†Activity was seen, however kinetic parameters could not be reliably measured.