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Stimulation of phosphatidylglycerolphosphate phosphatase activity by unsaturated fatty acids in rat heart
Author(s) -
Cao Shu Guang,
Hatch Grant M.
Publication year - 1994
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02578244
Subject(s) - oleic acid , biochemistry , acid phosphatase , phosphatase , chemistry , phosphatidic acid , enzyme , enzyme assay , arachidonic acid , fatty acid , phospholipid , membrane
Phosphatidylglycerolphosphate (PGP) synthase and PGP phosphatase catalyze the sequential synthesis of phosphatidylglycerol from cytidine‐5′‐diphosphate 1,2‐diacyl‐ sn ‐glycerol (CDP‐DG) and glycerol‐3‐phosphate. PGP synthase and PGP phosphatase activities were characterized in rat heart mitochondrial fractions, and the effect of fatty acids on the activity of these enzymes was determined. PGP synthase was observed to be a heat labile enzyme that exhibited apparent K m values for CDP‐PG and glycerol‐3‐phosphate of 46 and 20 μM, respectively. The addition of exogenous oleic acid to the assay mixture did not affect PGP synthase activity. PGP phosphatase was observed to be a heat labile enzyme, and addition of oleic acid to the assay mixture caused a concentration‐dependent stimulation of PGP phosphatase activity. Maximum stimulation (1.9‐fold) of enzyme activity was observed in the presence of 0.5 mM oleic acid, but the stimulation was slightly attenuated by the presence of albumin in the assay. The presence of oleic acid in the assay mixture caused the inactivation of PGP phosphatase activity to be retarded at 55°C. Stimulation of PGP phosphatase activity was also observed with arachidonic acid, whereas taurocholic, stearic and palmitic acids did not significantly affect PGP phosphatase activity. The activity of mitochondrial phosphatidic acid phosphohydrolase was not affected by inclusion of oleic acid in the incubation mixture. We postulate that unsaturated fatty acids stimulate PGP phosphatase activity in rat heart.