Arachidonoyl-hydrolyzing phospholipase A2 plays a central role in providing substrate for the synthesis of the potent lipid mediators of inflammation, the eicosanoids, and platelet-activating factor. Although Ca2+ is required for arachidonic acid release in vivo and most phospholipase A2 enzymes require Ca2+ for activity in vitro, the role of Ca2+ in phospholipase A2 activation is not understoo...

Thrombin stimulates phospholipase C and inhibits adenylate cyclase in human platelets. We have studied the effect of purified S1 monomer, the ADP-ribosylating subunit of pertussis toxin, on these receptor-coupled G-protein-dependent activities. ADP-ribosylation of a 41 kDa protein is associated with a marked decrease in the ability of thrombin to inhibit cyclic AMP formation, but has little eff...

Objective(s): The rotavirus nonstructural protein 4 (NSP4) is responsible for the increase in cytoplasmic calcium concentration through a phospholipase C-dependent and phospholipase C-independent pathways in infected cells. It is shown that increasing of intracellular calcium concentration in rotavirus infected cells is associated with the activation of some members of protein kinases family su...

A simple, high-yielding preparation of monolysocardiolipin (MLCL) by phospholipase A2 hydrolysis of cardiolipin (CL) in methanol on a semi-preparative scale is described. In methanol, phospholipase A2 preferentially hydrolyzes CL to MLCL. This selectivity results in ∼80% yield of MLCL. The synthesized MLCL and dilysocardiolipin were characterized by NMR and ESI-MS/MS. Only the sn-2 position of ...

Diagnosis of snake envenomation is challenging but critical for deciding on antivenom use. Phospholipase A2 enzymes occur commonly in snake venoms and we hypothesized that phospholipase activity detected in human blood post-bite may be indicative of envenomation. Using a simple assay, potentially a bedside test, we detected high phospholipase activity in sera of patients with viper and elapid e...

This study reports the existence of phospholipase C and D enzymatic activities in Mycobacterium ulcerans cultures as determined by use of thin-layer chromatography to detect diglycerides in hydrolysates of radiolabeled phosphatidylcholine. M. ulcerans DNA sequences homologous to the genes encoding phospholipase C in Mycobacterium tuberculosis and Pseudomonas aeruginosa were identified by sequen...

We evaluated phospholipase activity in the intestine of rats and other species. Phospholipase activity was assayed by a surface barostat technique or an egg yolk titration system. Mucosal activity was found only by the surface barostat technique with phosphatidylglycerol as substrate; it was not found with phosphatidylcholine as substrate in assays by either technique. In gut luminal fluid acti...

OBJECTIVE A novel phospholipase assay was used to measure for the first time the behavior of endothelial and hepatic phospholipase activities in postheparin human plasma of hemodialyzed patients and its relationship with atherogenic and antiatherogenic lipoprotein levels. METHODS AND RESULTS Endothelial and hepatic phospholipase activity was assessed in a total SN1-specific phospholipase assa...

An assay procedure was developed in which phosphatidyl[2-(3)H]inositol was employed as substrate for the measurement of phosphatidylinositol-specific phospholipase C activity. Employing this assay, phosphatidylinositol-specific phospholipase C activity in human fetal membranes and uterine decidua was identified and characterized. The specific activity of this enzyme in amnion (4.4 mumol x mg(-1...

The activation of phospholipase A2 is believed to have an important role in the inflammatory process owing to its induction of eicosanoids, platelet activating factor, and other mediators. Soluble phospholipase A2 has been associated with exudates in different inflammatory conditions. In this review the general physiology and control of this enzyme and, in particular, the most recent findings o...