Effects of phospholipids in the action of acetyl-CoA carboxylase from rat liver.

Acetyl-CoA carboxylase (E.C. 6.4.1.2) was isolated from rat liver. The purified enzyme contains phospholipids with a rather large amount of phosphatidylinositol (26%). Incubation of the purified acetyl-CoA carboxylase with phospholipase A2 (E.C. 3.1.1.4) or with phospholipase D (E.C. 3.1.1.4) diminishes the phospholipid content by 70%, this treatment leading to a complete inactivation of the enzyme. After removal of the phospholipases, the lipid-depleted enzyme can be reactivated to a certain degree by incubation with a phospholipid extract from rat liver, with phosphatidylinositol alone, or with serum albumin.