2.4.1.58 phosphatidylethanolamine requirement, most effective phospholipid, phosphatidylethanolamine containing unsaturated or cyclopropane acyl groups is more effective than that containing saturated acyl groups 2.4.1.58 Phospholipid - 2.4.1.58 Phospholipid requirement 2.4.1.58 Phospholipid activates, minimal activity in absence