PHOSPHOLIPID REQUIREMENTS OF MEMBRANE-BOUND CHITIN SYNTHASE FROM ABSIDIA-GLAUCA

Membrane-bound chitin synthase, a key enzyme in chitin biosynthesis, had a specific requirement for phospholipid. The activity of the enzyme was enhanced 2.7-fold by adding phosphatidylinositol from porcine liver but not by other phospholipids. Each of the constituents of phospholipids inhibited enzyme activity at concentrations over 0.05%. Sterols and glycolipids had little effect on chitin synthase activation. Moreover, investigation using defined species of phosphatidylcholine revealed that 1-palmytoyl-2-arachidoyl and 1-stearoyl-2-arachidoyl phosphatidylcholine activated the enzyme. In contrast to the arachidoyl acyl chain, other species having unsaturated fatty acyl chains inhibited enzyme activity at a concentration of 0.01%.