The interrelationships between activation of phospholipases and neutrophil stimulus-induced Ca2+ responses remain unclear. We report here that immune complexes activate a phosphatidylcholine-specific phospholipase A in a neutrophil only after the cytoplasmic Ca2+ transient has been initiated in the same cell, while chemotactic peptide activation does not proceed via such a phospholipase A-media...

1. Exposure of submitochondrial particles to phospholipases impaired the rate of oxidation as well as phosphorylation. Phospholipase A and phospholipase C were more inhibitory to phosphorylation and to NADH oxidation than to succinate oxidation. 2. At low concentrations of phospholipase A the inhibition of phosphorylation was prevented to a considerable extent by the presence of large amounts o...

Phospholipase D plays a key role in the biosynthesis of phosphatidic acid, a second messenger involved in essential cellular processes. Oleate-activated phospholipase D was the first mammalian phospholipase D isoform to be discovered but is the least known. The study was aimed to test a fluorometric method of assessment of oleate-activated phospholipase D activity in different biological materi...

The proliferative properties and the ability to stimulate the Na+/H+antiport activity of a secretory phospholipase A2 were studied in rat aortic smooth muscle cells in culture. The requirement of the enzymatic activity of phospholipase A2 to elicit mitogenesis was assessed by the use of ammodytin L, a Ser49 phospholipase A2 from the venom of Vipera ammodytes, devoid of hydrolytic activity. We p...

Rabbit antisera elicited against pure pig, horse, ox, and sheep pancreatic phospholipase A2 revealed considerable immunological differences when tested by double immunodiffusion and microcomplement fixation assays. Snake venom phospholipases did not show any detectable cross-reactions with the pancreatic enzymes. Microcomplement fixation also clearly demonstrated conformational differences betw...

Pneumolysin has been identified as a virulence factor in Streptococcus pneumoniae disease. In addition to producing tissue injury through its cytolytic effect, pneumolysin might injure tissues indirectly by eliciting an inflammatory response. We demonstrate for the first time that pneumolysin is a rapid and potent activator of cellular phospholipase A in bovine pulmonary artery endothelial cell...

abstract bee venom is a complex mixture of proteins, peptides and low molecular components: proteins (enzymes) :( phospholipase, a2phospholipase b, hyaluronidase α – glucosidase) - , peptides (melittin, apamine mcd peptide,adolapine ,procamine a and b, protease inhibitors)- low molecular components: biogenic amines:( histamine, dopamine and noradrenalin) - pheromones: complex ethers- sugars :( ...

The majority of phospholipase A2 activity in myocardium is calcium-independent and selective for hydrolysis of plasmalogen substrate (Wolf, R. A., and Gross, R. W. (1985) J. Biol. Chem. 260, 7295-7303; Hazen, S. L., Stuppy, R. J., and Gross, R. W. (1990) J. Biol. Chem. 265, 10622-10630). Accordingly, identification of an inhibitor which selectively targets calcium-independent phospholipases A2 ...

GTP-binding proteins have been implicated to function as key transducing elements in the mechanism underlying receptor activation of a membrane-associated phospholipase C activity. In the present study, the regulation of phospholipase C activity by GTP-binding proteins has been characterized in a detergent-solubilized system derived from bovine brain membranes. Guanosine-5'-(3-O-thio)triphospha...