Substrate selectivity of diacylglycerol kinase in guinea pig brain.

The present study was conducted to test the selectivity of the microsomal diaclyglycerol kinase (ATP:1,2-diacyl-sn-glycerol-phosphotransferase) from guinea pig brain towards different, 1,2-diacyl-sn-glycerols. The molecular species added to the incubation medium as substrates were a mixture of the 1-[3H]palmitoyl plus 1-[14C]stearoyl homologs of either the monoenoic (2-oleoyl), dienoic (2-linoleoyl), tetraenoic (2-arachidonoyl), or hexaenoic (2-docosahexaenoyl) diacylglycerols. Rates of phosphatidic acid synthesis (1-palmitoy plus 1-stearoyl homologs) with each of the four classes of unsaturated diacylglycerols were not greatly different, although they were moderately higher in the case of the monoenes. No marked enzyme selectivity for either the 1-palmitoyl or 1-stearoyl homolog of the various 1-saturated 2-unsaturated diacylglycerols was apparent. Generally similar results were obtained with the diacylglycerol kinase in rat brain microsomes.