Phosphatidylinositol phosphodiesterase activated by diacylglycerol is substantially inhibited by all phospholipids containing a phosphocholine head group, including phosphatidylcholine, hydrogenated phosphatidylcholine, choline plasmalogen, lysophosphatidylcholine, lysocholine plasmalogen, sphingomyelin and sphingosylphosphocholine. The sphingosine-containing phospholipids are the most inhibito...

We demonstrate that lipidomics coupled with molecular dynamics reveal unique phospholipase A2 specificity toward membrane phospholipid substrates. We discovered unexpected headgroup and acyl-chain specificity for three major human phospholipases A2. The differences between each enzyme's specificity, coupled with molecular dynamics-based structural and binding studies, revealed unique binding si...

The fatty acyl specificity of phospholipase A1 and A2 in homogenates of mouse bone marrow-derived macrophages was determined using phosphatidylcholine and phosphatidylethanolamine of different acyl chain composition. Phosphatidylcholine with arachidonoyl at position 2 was cleaved preferentially by an alkaline phospholipase A2 (pH-optimum 9.0) leading to selective liberation of arachidonic acid....

The role of phospholipids in the activity of UDP-D-galactose: D-xylose galactosyltransferase (galactosyltransferase I) from embryonic chick cartilage was investigated. Phospholipase C treatment of particulate galactosyltransferase I caused inactivation of this enzyme to the extent of 60 to 70% as well as hydrolysis of 75 to 80% of the membrane phospholipids. Addition of phospholipid restored ac...

We have examined the effects of phospholipase C from Bacillus cereus on the extent of phospholipid hydrolysis in envelope membrane vesicles and in intact chloroplasts. When isolated envelope vesicles were incubated in presence of phospholipase C, phosphatidylcholine and phosphatidylglycerol, but not phosphatidylinositol, were totally converted into diacylglycerol if they were available to the e...

The role of phospholipids in the activity of UDP-D-galactose:D-xylose galactosyltransferase (galactosyltransferase I) from embryonic chick cartilage was investigated. Phospholipase C treatment of particulate galactosyltransferase I caused inactivation of this enzyme to the extent of 60 to 70% as well as hydrolysis of 75 to 80% of the membrane phospholipids. Addition of phospholipid restored act...

The hydrolytic activity of phosphatidylcholine phospholipase D in the synaptosomes from canine brain was examined using a radiochemical assay with 1,Z-dipalmitoyl-sn-glycerol-3-phosphoryl[3H]choline as the exogenous substrate. The involvement of G protein(s) in regulation of this enzyme was demonstrated by a 2to %fold stimulation of the basal activity (4.81 2 0.44 nmol choline released/mg prote...

We have studied the effects of two stable prostaglandin endoperoxide analogues on platelet lipid metabolism in relation to specific platelet functional changes. During platelet shape change, the endoperoxide analogues induce the formation of 1,2-diacylglycerol and phosphatidic acid, indicating the activation of a phosphoinositide-specific phospholipase C. In parallel, they stimulate the phospho...

Secretory phospholipase A2 (sPLA2) is a critical component of insect and snake venoms and is secreted by mammalian leukocytes during inflammation. Elevated secretory PLA2 concentrations are associated with autoimmune diseases and septic shock. Many sPLA2's do not bind to plasma membranes of quiescent cells but bind and digest phospholipids on the membranes of stimulated or apoptotic cells. The ...