Table 3.

O-methylation of PAH catechols by COMT.

Quinone	kcat/Km	Substrate inhibition	M1a	M2b
	(min−1 μM−1)		(%)	(%)
Naphthalene-1,2-dione	4.9	−	100	0
Chrysene-1,2-dione	1.7	+	62	38
Chrysene-3,4-dione	0.02	−	83	16
5-Methyl-chrysene-7,8-dione	10.1	+	55	45
Benz[a]anthracene-3,4-dione	4.0	+	59	41
7-Methylbenz[a]anthracene-3,4-dione	1.6	+	53	47
12-Methylbenz[a]anthracene-3,4-dione	9.0	+	62	38
7,12-Dimethylbenz[a]anthracene-3,4-dione	6.8	+	32	68
Benzo[c]phenanthrene-3,4-dione	3.5	−	67	34
B[a]P-7,8-dione	0.7	−	90	10
Benzo[g]chrsyene-11,12-dione	8.0	+	36	64
Pyrocatechol	0.2	−	NA	NA

a%, Product as isomer 1; b%, Product as isomer 2.

+, Where substrate inhibition is observed; −, substrate inhibition is not observed.

Data from: Zhang et al., 2011.