Glyceryl-Ether Monooxygenase (EC 1.14.16.5): Nature of the Glyceryl-Ether Lipid Substrates in Aqueous Buffer

The kinetics of inhibition of glyceryl-ether monooxygenase with 6-methyl-5,6,7,8-tetrahydropterin as cofactor (saturating) by the detergent Mega-10 with batyl alcohol and (RS)-3-(1-hexadecyloxy)-2-hydroxypropane-1-phosphocholine as substrates exhibited noncompetitive inhibition with apparent Ki values of 1.74 +/- 0.37 mM and 185 +/- 23 microM, respectively. Inhibition by octadecan-1-ol (with batyl alcohol as substrate in the presence of 2.3 mM Mega-10) was competitive with an apparent Ki value of 765 +/- 80 microM. The critical micelle concentration values of various solutions of Mega-10 were determined and used to show that the active ether-lipid substrates were in micelle form (for a water soluble substrate) or mixed micelle form (for substrates solubilised with Mega-10).