Phospholipid requirement of alkylglycerol monooxygenase from rat liver microsomes

The alkylglycerol monooxygenase catalyzing the cleavage of the ether bond in alkylglycerol resides in rat liver microsomes. The enzyme preparation was freed of phospholipids by sodium deoxycholate treatment followed by gel filtration in the presence of deoxycholate. The removal of phospholipids markedly decreased the alkylglycerol monooxygenase activity. The activity of the delipidated enzyme, however, could be completely restored by the addition of phospholipid vesicles without detergent. When individual phospholipids were added, anionic phospholipids such as phosphatidylglycerol and diphosphatidylglycerol were the most effective. These findings, along with our previous observation of a similar effect of liposomes on the purified enzyme, indicate that the amphipathic nature of the protein is responsible for the lipid dependence of enzymatic activity.