TABLE 3.

3-Methoxycatechol, methoxyhydroquinone, and 4-methoxyresorcinol synthesis from o-methoxyphenol by E. coli TG1 expressing wild-type T4MO and saturation mutagenesis TmoA variants^a

Enzyme	Regiospecificity of o-methoxyphenol oxidation (%)			3-Methoxycatechol formation rate (nmol/min/mg of protein)			Methoxyhydroquinone formation rate (nmol/ min/mg of protein)c	o-Methoxyphenol oxida- tion (nmol/min/mg of protein)
	4-Methoxy- resorcinol	3-Methoxy- catechol	Methoxyhydro- quinone	Via HPLC	Relative activityb	Via colori- metric assay
Wild type	87	11	2	0.21 ± 0.01	1	0.2	0.07 ± 0.03	4.1 ± 1.1
I100L	73	20	7	0.8 ± 0.2	4	0.9-1.3	∼0	2.4 ± 0.8
G103A	41	52	7	1.2 ± 0.2	6	0.7-2.7	∼0	2.1 ± 0.5
G103A/A107S	13	82	5	1.5 ± 0.2	7	1.9	∼0	1.9
G103S	19	<1	80	∼0	0	0	0.36 ± 0.01	0.4
G103S/A107T	35	30	35	NDd	0	0	0.08	ND

^aActivity was determined at a saturation substrate concentration of 1 mM.

^bRelative values based on HPLC analysis. The colorimetric assay corroborated the data.

^cThe o-methoxyphenol substrate was oxidized to as many as three different products, but only the methoxyhydroquinone formation rate is shown.

^dND, not determined.