TABLE 2.

Evaluation of MelH potential epoxide substrates

Epoxide tested	Structure	Activity observed by TLC and NMRa	Percent inhibition (%) observed at 25 μMb
Vitamin K1 2,3-epoxide		+++	25
2-Biphenylyl glycidyl ether		–	94
Styrene oxide		+++	64
1,4-Naphthoquinone 2,3-epoxide		+	99
(E)-1,3-Diphenyl-2,3-epoxypropan-1-one		–	98

^a Each substrate (50 μM) was incubated with 150 ng of MelH at pH 7.5, 37°C for 1 h. Reactions were quenched, and the extracted organic layer was analyzed by thin-layer chromatography and ¹H-NMR spectroscopy. +++ reaction, 100% complete; ++ reaction, 70% complete; + reaction, 30% complete in 1 h; – reaction, 0% complete.

^b The initial velocity of epoxy fluor substrate turnover was measured in the presence of 25 μM of the indicated epoxide at pH 7.5, at 37°C for 10 min, and the rate of turnover compared to the negative control without addition of a second epoxide.