PRIMARY ALCOHOLS AND PHOSPHATIDYLCHOLINE METABOLISM IN RAT-BRAIN SYNAPTOSOMAL MEMBRANES VIA PHOSPHOLIPASE-D

Phospholipase D of rat brain synaptosomal membranes was tested with ph osphatidylcholine as the substrate for its specificity in the use of p rimary alcohols as transphosphatidylation co-substrates. The efficienc y of the reaction was related to the hydrophobicity and the membrane p enetrating capacity of the alcohol molecule. Phosphatidylalcohol forma tion could be detected up to 1-octanol but not for alcohols with longe r hydrocarbon chains (C-9, C-10). With increasing alcohol concentratio n the transphosphatidylation activity of the phospholipase D reached a n optimum and then declined abruptly. Alcohol concentrations required for maximal transphosphatidylation reaction generally decreased with i ncreasing hydrophobicities of the alcohols. Nevertheless 1-butanol and 4-chloro-1-butanol were the most efficient cosubstrates, sharing iden tical optimal conditions. Transphosphatidylation works at the cost of phosphatidic acid formation. Phosphatidic acid itself was transformed to diacylglycerol, probably by a contaminating phosphatidic acid phosp hohydrolase.