Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.4.3 (phospholipase C)
 18,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phospholipids are the major components of pulmonary surfactant. Dipalmitoylphosphatidylcholine is believed to be especially essential for the surfactant function of reducing the surface tension at the air-liquid interface. Surfactant protein A (SP-A) with a reduced denatured molecular mass of 26-38 kDa, characterized by a collagen-like structure and N-linked glycosylation, interacts strongly with a mixture of surfactant-like phospholipids. In the present study the direct binding of SP-A to phospholipids on a thin layer chromatogram was visualized using 125I-SP-A as a probe, so that the phospholipid specificities of SP-A binding and the structural requirements of SP-A and phospholipids for the binding could be examined. Although 125I-SP-A bound phosphatidylcholine and sphingomyeline, it was especially strong in binding dipalmitoylphosphatidylcholine, but failed to bind phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, and phosphatidylserine. Labeled SP-A also exhibited strong binding to distearoylphosphatidylcholine, but weak binding to dimyristoyl-, 1-palmitoyl-2-linoleoyl-, and dilinoleoylphosphatidylcholine. Unlabeled SP-A readily competed with labeled SP-A for phospholipid binding. SP-A strongly bound dipalmitoylglycerol produced by phospholipase C treatment of dipalmitoylphosphatidylcholine, but not palmitic acid. This protein also failed to bind lysophosphatidylcholine produced by phospholipase A2 treatment of dipalmitoylphosphatidylcholine. 125I-SP-A shows almost no binding to dipalmitoylphosphatidylglycerol and dipalmitoylphosphatidylethanolamine. The addition of 10 mM EGTA into the binding buffer reduced much of the 125I-SP-A binding to phospholipids. Excess deglycosylated SP-A competed with labeled SP-A for binding to dipalmitoylphosphatidylcholine, but the excess collagenase-resistant fragment of SP-A failed. From these data we conclude that 1) SP-A specifically and strongly binds dipalmitoylphosphatidylcholine, 2) SP-A binds the nonpolar group of phospholipids, 3) the second positioned palmitate is involved in dipalmitoylphosphatidylcholine binding, and 4) the specificities of polar groups of dipalmitoylglycerophospholipids also appear to be important for SP-A binding, 5) the phospholipid binding activity of SP-A is dependent upon calcium ions and the integrity of the collagenous domain of SP-A, but not on the oligosaccharide moiety of SP-A. SP-A may play an important role in the regulation of recycling and intra- and extracellular movement of dipalmitoylphosphatidylcholine.
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PMID:Pulmonary surfactant protein A (SP-A) specifically binds dipalmitoylphosphatidylcholine. 199 79

In order to investigate the mechanism of dipalmitoylphosphatidylcholine (DPPC, L-alpha-lecithin) stimulation of the prostaglandin E (PGE) production of the amniotic membrane, effects of DPPC (50-800 micrograms/ml) on phospholipase A2 (PLA2), phospholipase C (PLC), PG endoperoxide synthase, and PGE synthase activities of human amniotic membrane were studied. Only PLA2 activity was increased by DPPC, suggesting that lecithin, the major surfactant component, increases the PGE production of the amniotic membrane by activating PLA2.
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PMID:Dipalmitoylphosphatidylcholine (L-alpha-lecithin) stimulates phospholipase A2 activity in human amnion. 211 32

A phospholipase C in bile, free of bacterial infection, has recently been identified from cholesterol gallstone patients. Because of the importance of phosphatidylcholine in solubilizing cholesterol in bile, this study further investigates the metabolism of phosphatidylcholine in delipidated gallbladder and common bile duct biles. Phospholipase C activity, as measured by the release of phosphoryl[3H]choline from the substrate 1,2-dipalmitoyl-sn-glycero-3-phospho [N-methyl-3H]choline, was identified in both hepatic and gallbladder biles. Similar levels of activity (nmol.h-1.mg-1 of delipidated protein) were found in common bile duct (11.25 +/- 14.23) and gallbladder bile (19.07 +/- 22.24), although per milliliter of bile, the mean gallbaldder levels were 6.4 times greater than those found in common duct bile. With the tow substrates, 1-palmitoyl-2[9,10-3H] palmitoyl-sn-glycero-3-phosphocholine and 1,2(1-14C) dipalmitoyl-sn-glycero-3-phosphocholine, the majority of organically extracted label, after thin-layer chromatography, was recovered as radiolabeled diglyceride, confirming the presence of phospholipase C. Diglyceride levels were found to be closely correlated with [3H]choline (slope, 0.9820; r = 0.9844). In addition to diglyceride, both radiolabeled free fatty acid and monoglyceride were identified in common bile duct and gallbladder biles, although their levels were an order of magnitude less than measurable phospholipase C activity. To determine whether the free fatty acid release was due to either a diacylglycerol-lipase or a phospholipase A2, the effect of adding unlabeled diglyceride on free fatty acid formation from the substrate [14C]DPPC was examined. As the concentration of unlabeled diglyceride was increased, the amount of free fatty acid and monoglyceride released were both reduced in parallel. Direct measurement of diacylglycerol-lipase activity by incubating the diglyceride, sn-2[3H]dipalmitoyl, resulted in release of both products in a ratio similar to that found with sn-2[3H]DPPC. Finally, no radiolabeled lysolecithin was identified with [3H]choline-DPPC or [14C]DPPC as substrate indicating the free fatty acid was the product of a diacylglycerol-lipase rather than a phospholipase A2. Phospholipase C and diacyl-glycerol-lipase activities were significantly correlated (P less than 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Phospholipase C and diacylglycerol lipase in human gallbladder and hepatic bile. 206 34

Activity of phospholipase C from Clostridium perfringens on liposomes made from sn-3-phosphatidylcholine, dimyristoyl (DMPC), dipalmitoyl (DPPC) or distearoyl (DSPC) was measured at various temperatures and was correlated with their gel/liquid-crystalline phase transitions (Tc:23, 41.5, 52 degrees C for DMPC, DPPC, DSPC, respectively). In all cases, the activity of phospholipase C was high in the gel phases of the substrates and was almost zero in their liquid-crystalline phases. Fluorescence depolarization measurements of N-dansyl-sn-3-phosphatidylethanolamine (DPE) and 1,6-diphenyl-1,3,5-hexatriene (DPH) incorporated into the liposomes showed that both the head group and the alkyl chains of the lipids were immobilized in the gel phases but were highly mobile in the liquid-crystalline phase. These results indicate that the rotational mobility of lipids (both of the head groups and the alkyl chains) was not a major factor in the phospholipase C reaction. It is inferred that some electrostatic and/or hydrophobic interactions might play important roles in regulation of the phospholipase C activity.
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PMID:Phospholipase C and the physical states of polar head groups of lipids. 359 67

The hydrolytic reaction of L-alpha-dipalmitoylphosphatidylcholine (L-DPPC) monolayer catalyzed by phospholipase C (PLC) has been investigated using monomolecular membrane technique and Brewster angle microscopy (BAM) at the air/water interface. The curves of surface pressure as a function of time determined a lag-burst process of L-DPPC monolayer hydrolysis by PLC. The BAM images recorded the changes of domains formed in the coexistence region of liquid-condensed (LC) and liquid-expanded (LE) phases during the monolayer hydrolysis. The changes of domain shape and size and the increase of domain number reflect the decrease of reactant and molecular rearrangement process of the main hydrolysis product, dipalmitoylglycerol (DPG). A new phase was observed after the hydrolysis reaction was completed.
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PMID:Dynamic and morphological investigation of phospholipid monolayer hydrolysis by phospholipase C. 1250 17