Table II.

The activity of purified dHG-6-OMT with different cosubstrates

Reactiona	Enzyme Activity
	at/mg
Complete	2.67
+Mg2+ (5 mm)	2.49
−dHG	0.08
−dHG, + hemigossypol	0.06
−Enzyme, + boiled enzyme	0.06
−dHG, + 2.7-dihydroxycadalene	0.06
−dHG, + caffeic acid	0.09
−dHG, + 4-methylcatechol	0.09
−dHG, + 2,3-dihydroxynaphthalene	0.11

^aComplete reaction mixture contained 50 μL of purified enzyme preparation, 60 μL of 0.1 m Tris-HCI buffer, pH 7.5, containing 5 mm GSH, 40 μL of 188 μm dHG dissolved in ethanol, and 0.1 m Tris-HCI buffer, pH 7.5, in a 1:9 ratio, and 10 μL of [methyl- ³H]-SAM (16.2 nmol and 1.25 μCi of radioactivity) for a total volume of 160 μL. Numbers in parentheses refer to the final concentration. Substrates hemigossypol, 2,7-dihydroxycadalene, caffeic acid, 4-methylcatechol, and 2,3-dihydroxynaphthalene were added in the same amounts as for dHG.