CONVERSION OF LYSOPHOSPHOLIPIDS TO CYCLIC LYSOPHOSPHATIDIC ACID BY PHOSPHOLIPASE-D

Phospholipase D from Streptomyces chromofuscus hydrolyzes lysophosphat idylcholine or lysophosphatidylethanolamine in aqueous 1% Triton X-100 solution. In situ monitoring of this reaction by P-31 NMR revealed th e formation of cyclic lysophosphatidic acid (1-acyl 2,3-cyclic glycero phosphate) as an intermediate which was hydrolyzed further by the enzy me at a functionally distinct active site to lysophosphatidic acid (ly so-PA). Synthetic cyclic lyso-PA (1-octanoyl 2,3-cyclic glycerophospha te) was found to be stable in aqueous neutral solutions at room temper ature. It was hydrolyzed by the bacterial phospholipase D to lyso-PA a t a rate which was approximately 4-fold slower than the rate of format ion of cyclic lyso-PA. The addition of 5-10 mM sodium vanadate could p artially inhibit the ring opening reaction and thus increase substanti ally the cyclic lyso-PA accumulation. Cyclic lyso-PA may act as a dorm ant configuration of the physiologically active lyso-PA or may even po ssess specific activities which await verification.