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SUITABILITY OF DIFFERENT MOLECULAR SPECIES OF 1,2‐DIACYLGLYCEROLS AS SUBSTRATES FOR DIACYLGLYCEROL KINASE IN RAT BRAIN MICROSOMES
Author(s) -
Holub B. J.,
Piekarski J.
Publication year - 1978
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1978.tb00126.x
Subject(s) - diacylglycerol kinase , phosphatidic acid , chemistry , diglyceride , enzyme , monoacylglycerol lipase , biochemistry , protein kinase c , stereochemistry , phosphatidate , microsome , phospholipid , endocannabinoid system , receptor , membrane
The relative suitability of different molecular species of 1,2‐diacyl‐ sn ‐glycerols as substrates for the diacylglycerol kinase (ATP: 1,2‐diacyl‐ sn ‐glycerol phosphotransferase) in rat brain microsomes was investigated. The diacylglycerols tested were a mixture of the 1‐[ 3 H]palmitoyl and 1‐[ 14 C]stearoyl homologues of either the 2‐oleoyl (monoenoic), 2‐linoleoyl (dienoic), 2‐arachidonoyl (tetraenoic), or 2‐docosahexaenoyl (hexaenoic) diacylglycerols with an isotope ratio ( 3 H/ 14 C) approximately equal to 1.00. At substrate concentrations of 0.125 mM and 0.60 mM, only a modest preference of the kinase for total (1‐palmitoyl plus 1‐stearoyl homologues) monoenoic over total hexaenoic species was indicated. The tetraenoic diacylglycerols gave reaction rates which were not significantly different from the monoenes, dienes, or hexaenes when the data were analyzed statistically. No significant enzyme selectivity for either the 1‐palmitoyl or 1‐stearoyl homologues of the various 1‐saturated 2‐unsaturated diacylglycerols was apparent. The present results, together with data on the composition of free 1,2‐diacylglycerols in brain, which reveal a preponderance of tetraenoic molecular species, suggest that the tetraenoic phosphatidic acids (mainly as 1‐stearoyl 2‐arachidonoyl species) are quite possibly the major products of diacylglycerol kinase activity in rat brain under physiological conditions.