PHOSPHOINOSITOL DIPHOSPHATES - NONENZYMATIC FORMATION INVITRO AND OCCURRENCE INVIVO IN THE CELLULAR SLIME-MOLD DICTYOSTELIUM

When extracts of avian red blood cells were lyophilised, a compound was generated from myo-inositol 1,3,4,5,6-pentakisphosphate and ATP which, on the basis of HPLC analysis, limited acid hydrolysis, and P-31 and H-1 NMR analysis, was identified as tetrakisphospho-myo-inositol diphosphate (InsP4-PP). The formation of pyrophosphoryl residues occurs whenever inositol phosphates are lyophilised together with stoichiometric amounts of phosphocreatine and/or nucleoside tri- or di-phosphates. Aqueous extracts of the cellular slime mold Dictyostelium contained two major phosphoinositol diphosphates each of which was converted into myo-inositol hexakisphosphate by mild acid hydrolysis. The components were shown not to be artifacts and were identified tentatively by HPLC, chemical, and NMR analysis as pentakisphospho-myo-inositol diphosphate (InsP5-PP) and tetrakisphospho-myo-inositol bis(diphosphate) (InsP4-PP2).