Table 2.

Summary of kinetic constants for regioselective sulfation of phenolics

Substrates	Position	Enzyme source	Km(µM)	Vmax(pmol/min/mg) or Kcat	Vmax/Km (µl/min/mg) or Kcat/Km
Caffeic acid# [13]	3-OH	Liver S9	13.4	204	15.2
	4-OH		11.9	52.7	4.43
	3-OH	Intestine S9	34.5	682	19.8
	4-OH		41.3	297	7.2
	3-OH	SULT1A1	11.6	62.1	5.35
	4-OH		14.8	17.6	1.19
Dihydrocaffeic acid# [13]	3-OH	Liver S9	106	165	1.56
	3-OH	Intestine S9	15.8	592	37.4
	3-OH	SULT1A1	34.1	108	3.17
Daidzein$ [14]	7-OH	SULT1A1	0.47	1.27	2702
	4’-OH		0.54	0.33	611
	7-OH	SULT1A3	N.D.	N.D.	N.D.
	4’-OH		407.1	0.30	0.7
	7-OH	SULT1E1	2.57	5.71	2216
	4’-OH		3.24	6.39	1972
	7-OH	SULT2A1	45.6	0.21	4.7
	4’-OH		51.1	0.02	0.4
Genistein$ [14]	7-OH	SULT1A1	0.51	6.71	13,157
	4’-OH		0.52	0.78	1500
	7-OH	SULT1A3	N.D.	N.D.	N.D.
	4’-OH		371.8	1.46	3.9
	7-OH	SULT1E1	2.79	7.25	2,682
	4’-OH		2.94	7.45	2,530
	7-OH	SULT2A1	25.5	0.37	14
	4’-OH		55.9	0.09	1.6
7-hydroxyflavone*	7-OH	SULT1A3	2.80	85,100	30,400
7,4’-dihydroxyflavone*	7-OH	SULT1A3	3.42	20,800	6,090
3,7-dihydroxyflavone*	7-OH	SULT1A3	1.85	79,700	43,000
Chrysin*	7-OH	SULT1A3	2.73	87,800	32,200
Galangin [31]	7-OH	SULT1A1	0.21	3,270	15,572
	7-OH	SULT1A3	37.1	822	22.2
	7-OH	SULT1E1	1.13	948	839
Hesperetin [33]	7-OH	SULT1A2	N.D.	N.D.	N.D.
	3’-OH		0.5	454,000	881,553
	7-OH	SULT1A3	12.5	89,900	7,178
	3’-OH		13.2	276,000	20,964
	7-OH	SULT1B1	3.9	3,540	899
	3’-OH		4.3	21,500	5,003
	7-OH	SULT1C4	0.1	87,400	1,117,263
	3’-OH		N.D.	N.D.	N.D.
	7-OH	SULT1E1	N.D.	N.D.	N.D.
	3’-OH		2.5	538,000	219,242
Resveratrol [36]	3-OH	Liver cytosol	3.56	20.1	5.65
	4’-OH		30.2	1.12	0.04
	3-OH	SULT1A1	79.8	46,484	582.4
	4’ -OH		61.5	282	4.59
	3-OH	SULT1E1	48.4	2,845	58.8
	4’ -OH		119	5,491	46.1
Dopamine [37]	3-OH	SULT1A3	2.59	344,000	134,000
	4-OH		2.21	45,400	20,800

^*Meng et al. (submitted); N.D., not detectable;

^#Parameters K_cat (S⁻¹) and K_cat/K_m (µM⁻¹•S⁻¹) were calculated;

^$Parameters K_cat (Min⁻¹) and K_cat/K_m (mM⁻¹ •Min⁻¹) were calculated.