PRACTICAL SYNTHESIS OF PHOSPHOINOSITIDES

THERE IS A CURRENT AND GROWING INTEREST IN THE ROLE OF MEMBRANE PHOSPHOINOSITIDES IN CELL BIOLOGY, ESPECIALLY IN RELATION TO THE TRANSMISSION OF CA2+ MEDIATED SIGNALS. THESE SIGNALS ARE GENERATED WHEN CELL-SURFACE RECEPTORS ARE ACTIVATED BY HORMONES, NEUROTRANSMITTERS, GROWTH FACTORS, AND OTHER AGONISTS, IN RELATION TO THE MECHANISM OF MALIGNANT TRANSFORMATIONS INDUCED BY ONCOGENES AND BY THE ACTIVATION OF KINASE C. SAMPLES OF PURE PHOSPHOINOSITIDES AND ANALOGS ARE IMPORTANT FOR RESEARCH AND AS POTENTIAL THERAPEUTIC AGENTS. PRACTICAL METHODS FOR THEIR PREPARATIONBY SYNTHESIS ARE NOT AVAILABLE, HOWEVER. THE OVERALL OBJECTIVE OF THIS PROPOSAL IS TO DEVELOP A GENERAL, SIMPLE, AND PRACTICAL METHOD FOR THE SYNTHESIS OF DISTINCT MOLECULARSPECIES OF PHOSPHATIDYLINOSITOL (PI), PHOSPHATIDYLINOSITOL- 4-PHOSPHATE (PIP), AND PHOSPHATIDYLINOSITOL-4,5- BISPHOSPHATE (PIP2), EACH CARRYING FATTYACYL RESIDUES OF CHOICE IN POSITIONS 1',2'. THE MIXTURES OF FATTYACYLS IN NATURAL PI AND DERIVATIVES WITH ANY DESIRED FATTYACYLS WILL BE REPLACED BY A DEACYLATION-REACYLATION CYCLE, OR BY REMOVAL AND REINTRODUCTION OF THE COMPLETE DIGLYCERIDE RESIDUE. THE SYNTHESIS DEPENDS ON AN INNOVATIVE APPLICATIONOF LIPASES IN A COMPOSITE CHEMICAL AND ENZYMATIC SEQUENCE. DURING PHASE I, THIS ASPECT AND THE PREREQUISITE PROTECTION AND DEBLOCKING OF THE INOSITOL HYDROXYLS WILL BE EVALUATED FOR THE PREPARATION OF SEMISYNTHETIC 1',2'-DIACYL-SN- GLYCEROPHOSPHOINOSITOLS FROM PI ISOLATED FROM SOY-LECITHIN, TO DETERMINE THE FEASIBILITY OF THE GENERAL STRATEGY.