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Abstract
The Mojave rattlesnake is a unique species of pit viper that expresses either a highly potent phospholipase A2 (PLA2)-dependent neurotoxin containing venom nearly devoid of fibrinogenolytic metalloproteinases (venom type A) or a hemotoxic venom with a high percentage of metalloproteinases and PLA2 without any neurotoxin present (venom type B) depending on its geographical location in the Southwestern United States and Mexico. Given that PLA2 have been demonstrated to affect coagulation, it was hypothesized that the anticoagulant effects of both type A and B venoms could be assessed by thrombelastography, and determination made if these venoms were heme modulated. Both venom types were exposed to carbon monoxide releasing molecule-2 or its inactivated molecule (0 or 100 µM) in isolation and then placed in human plasma with consequent coagulation kinetics assessed by thrombelastography. It was determined that type A venom was twice as potent as an anticoagulant compared to type B venom, and that both venoms were inhibited by carbon monoxide releasing molecule-2 but not its inactivated molecule. Given the lack of proteolytic activity of type A venom and the dependence of neurotoxicity on PLA2 activity, it may be possible that carbon monoxide could inhibit neurotoxicity based on inhibition of PLA2 anticoagulant activity. These data may serve as the rationale for extension of these observations into animal models to determine if CO may inhibit not just hemotoxic venom, but also PLA2-dependent neurotoxic venom.
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Nielsen VG. Carbon monoxide inhibits the anticoagulant activity of phospholipase A 2 purified from Crotalus adamanteus venom. J Thromb Thrombolysis 2019; 47:73-79. [PMID: 30374703 DOI: 10.1007/s11239-018-1763-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Snake venom contains a myriad of classes of enzyme which have been investigated for medicinal and toxinological purposes, including phospholipase A2 (PLA2), which is responsible for anticoagulant, myotoxic and neurotoxic effects. Given the importance of PLA2, the purposes of the present investigation were to characterize the coagulation kinetic behavior of a PLA2 purified from Crotalus adamanteus venom (Ca-PLA2) in human plasma with thrombelastography and determine if carbon monoxide could inhibit its activity. Coagulation kinetics were determined in human plasma with a range of Ca-PLA2 activity (0-2 U/ml) via thrombelastography. Then, using carbon monoxide releasing molecule-2 or its inactivated molecule (0 or 100 µM), the vulnerability of Ca-PLA2 activity to carbon monoxide mediated inhibition was assessed. Lastly, the inhibitory response of Ca-PLA2 activity to exposure to carbon monoxide releasing molecule-2 (0-100 µM) was determined. Ca-PLA2 activity degraded the velocity of clot growth and clot strength in an activity dependent, exponential manner. Carbon monoxide inhibited Ca-PLA2 activity in a concentration dependent fashion, with loss of detectable activity at 100 µM of carbon monoxide releasing molecule-2. These findings, while preliminary, open the possibility that other PLA2 contained in snake venom with multiple toxicities (e.g., myotoxin, neurotoxin) may be heme bearing and CO-inhibitable, which have profound potential basic and clinical science implications.
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Affiliation(s)
- Vance G Nielsen
- Department of Anesthesiology, The University of Arizona College of Medicine, 1501 North Campbell Avenue, P.O. Box 245114, Tucson, AZ, 85724-5114, USA.
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Ability of S-Adenosyl-L-Methionine to Ameliorate Lipoprotein-Induced Membrane Lipid Abnormalities and Cellular Dysfunctions in Human Liver Disease. ACTA ACUST UNITED AC 2012. [DOI: 10.1007/bf03258361] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Hoffman JR, Stout JR, Williams DR, Wells AJ, Fragala MS, Mangine GT, Gonzalez AM, Emerson NS, McCormack WP, Scanlon TC, Purpura M, Jäger R. Efficacy of phosphatidic acid ingestion on lean body mass, muscle thickness and strength gains in resistance-trained men. J Int Soc Sports Nutr 2012; 9:47. [PMID: 23035701 PMCID: PMC3506449 DOI: 10.1186/1550-2783-9-47] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 09/26/2012] [Indexed: 01/02/2023] Open
Abstract
UNLABELLED BACKGROUND Phosphatidic acid (PA) has been reported to activate the mammalian target of rapamycin (mTOR) signaling pathway and is thought to enhance the anabolic effects of resistance training. The purpose of this pilot study was to examine if oral phosphatidic acid administration can enhance strength, muscle thickness and lean tissue accruement during an 8-week resistance training program. METHODS Sixteen resistance-trained men were randomly assigned to a group that either consumed 750 mg of PA (n = 7, 23.1 ± 4.4 y; 176.7 ± 6.7 cm; 86.5 ± 21.2 kg) or a placebo (PL, n = 9, 22.5 ± 2.0 y; 179.8 ± 5.4 cm; 89.4 ± 13.6 kg) group. During each testing session subjects were assessed for strength (one repetition maximum [1-RM] bench press and squat) and body composition. Muscle thickness and pennation angle were also measured in the vastus lateralis of the subject's dominant leg. RESULTS Subjects ingesting PA demonstrated a 12.7% increase in squat strength and a 2.6% increase in LBM, while subjects consuming PL showed a 9.3% improvement in squat strength and a 0.1% change in LBM. Although parametric analysis was unable to demonstrate significant differences, magnitude based inferences indicated that the Δ change in 1-RM squat showed a likely benefit from PA on increasing lower body strength and a very likely benefit for increasing lean body mass (LBM). CONCLUSIONS Results of this study suggest that a combination of a daily 750 mg PA ingestion, combined with a 4-day per week resistance training program for 8-weeks appears to have a likely benefit on strength improvement, and a very likely benefit on lean tissue accruement in young, resistance trained individuals.
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Affiliation(s)
- Jay R Hoffman
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Jeffrey R Stout
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - David R Williams
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Adam J Wells
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Maren S Fragala
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Gerald T Mangine
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Adam M Gonzalez
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Nadia S Emerson
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - William P McCormack
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Tyler C Scanlon
- Human Performance Laboratory, University of Central Florida, Orlando, 32186, FL, USA
| | - Martin Purpura
- Increnovo LLC, 2138 E. Lafayette Pl, Milwaukee, 53202, WI, USA
| | - Ralf Jäger
- Increnovo LLC, 2138 E. Lafayette Pl, Milwaukee, 53202, WI, USA
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Jäger R, Purpura M, Kingsley M. Phospholipids and sports performance. J Int Soc Sports Nutr 2007; 4:5. [PMID: 17908342 PMCID: PMC1997116 DOI: 10.1186/1550-2783-4-5] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Accepted: 07/25/2007] [Indexed: 11/24/2022] Open
Abstract
Phospholipids are essential components of all biological membranes. Phosphatidylcholine (PC) and Phosphatidylserine (PS) are Phosphatidyl-phospholipids that are required for normal cellular structure and function. The participation in physical activity often challenges a variety of physiological systems; consequently, the ability to maintain normal cellular function during activity can determine sporting performance. The participation in prolonged intense exercise has been shown to reduce circulatory choline concentrations in some individuals. As choline is a pre-cursor to the neurotransmitter Acetylcholine, this finding has encouraged researchers to investigate the hypothesis that supplementation with PC (or choline salts) could enhance sporting performance. Although the available data that evaluates the effects of PC supplementation on performance are equivocal, acute oral supplementation with PC (~0.2 g PC per kg body mass) has been demonstrated to improve performance in a variety of sporting activities where exercise has depleted circulatory choline concentrations. Short term oral supplementation with soy-derived PS (S-PS) has been reported to attenuate circulating cortisol concentrations, improve perceived well-being, and reduce perceived muscle soreness after exercise. More recently, short term oral supplementation (750 mg per day of S-PS for 10 days) has been demonstrated to improve exercise capacity during high intensity cycling and tended to increase performance during intermittent running. Although more research is warranted to determine minimum dietary Phospholipid requirements for optimal sporting performance, these findings suggest that some participants might benefit from dietary interventions that increase the intakes of PC and PS.
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Affiliation(s)
- Ralf Jäger
- Increnovo LLC, 2138 E Lafayette Pl, Milwaukee, WI 53202, USA
| | - Martin Purpura
- Increnovo LLC, 2138 E Lafayette Pl, Milwaukee, WI 53202, USA
| | - Michael Kingsley
- Department of Sports Science, University of Wales Swansea, Singleton Park, Swansea, SA2 8PP, UK
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den Hartigh JC, van Bergen en Henegouwen PM, Boonstra J, Verkleij AJ. Cholesterol and phosphoinositides increase affinity of the epidermal growth factor receptor. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1148:249-56. [PMID: 8389198 DOI: 10.1016/0005-2736(93)90136-n] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The epidermal growth factor receptor (EGF-R) has been purified from human epidermoid carcinoma A431 cells by affinity chromatography in a single step using a monoclonal antibody (528) which competes with EGF for receptor binding. The purified EGF-R exhibits EGF inducible tyrosine kinase and autophosphorylation activity. Steady-state binding of EGF to the purified receptor revealed the presence of one class of binding sites exhibiting an apparent dissociation constant (Kd) of approx. 2 nM. When Angiotensin II was used as a receptor tyrosine kinase substrate the specific activity of the EGF induced kinase was 87 nmol/min per mg and the Km of the reaction was about 2 mM. Reconstitution of the EGF receptors into lipid vesicles was achieved by octylglucoside dialysis. Reconstitution of the receptor into pure dioleoylphosphatidylcholine (DOPC) vesicles had no effect on the EGF-binding properties in comparison to receptors in Triton X-100 micelles. Binding of EGF to the reconstituted receptor with ATP and Angiotensin II incorporated into the vesicles resulted in a five fold stimulation of the receptor kinase activity. The introduction of cholesterol, ranging from 10% to 50% (w/w), into DOPC vesicles resulted in an increase of the affinity of the receptor for its ligand. The Kd for EGF decreased from 1.8 nM in pure DOPC vesicles to 0.3 mM in DOPC/cholesterol (1:1 (w/w)) vesicles. With the introduction of small amounts (2% (w/w)) of phosphatidylinositol lipids into DOPC vesicles the Kd changed from 1.8 nM to 0.2 nM with phosphatidylinositol (PtdIns) and phosphatidylinositol 4,5-biphosphate (PtdIns4,5-P2) and to 0.1 nM in the case of phosphatidylinositol 4 phosphate (PtdIns4-P). No change in affinity was found when equal amounts of phosphatidylserine (PS) or phosphatidic acid (PA) were used.
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Affiliation(s)
- J C den Hartigh
- Department of Molecular Cell Biology, University of Utrecht, The Netherlands
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Supernovich C, Crain R, Rosenberg P. Phosphatidylcholine asymmetry in electroplax from the electric eel: use of a phosphatidylcholine exchange protein. J Neurochem 1991; 57:575-84. [PMID: 2072103 DOI: 10.1111/j.1471-4159.1991.tb03788.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Phosphatidylcholine asymmetry in the inner and outer leaflets of the plasma membrane bilayer of the innervated and noninnervated surfaces of the electroplax cell was determined, using a phosphatidylcholine exchange protein. The exchange protein from bovine liver catalyzed the exchange of phosphatidylcholine from small unilamellar vesicles to the outer monolayer of the plasma membrane bilayer. The exchange protein did not penetrate to the inner monolayer of the plasma membrane, did not modify the permeability of the electroplax, and did not alter the phospholipid or cholesterol content of the electroplax. In the innervated plasma membrane, 42% of the phosphatidylcholine is in the outer leaflet, 33% is in the inner leaflet, and 25% is inaccessible to the exchange protein. Corresponding values for the noninnervated plasma membrane are 56, 26, and 18%, respectively. These results are similar to phosphatidylcholine asymmetry in other biological membranes. This unique cell can be used as a model to test the effects on phospholipid asymmetry of compounds that act on the membrane.
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Affiliation(s)
- C Supernovich
- Section of Pharmacology and Toxicology, School of Pharmacy, University of Connecticut, Storrs 06269
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Supernovich C, Crain R, Rosenberg P. Effect of soman and sarin on phosphatidylcholine asymmetry in the electroplax from the electric eel. J Neurochem 1991; 57:585-93. [PMID: 2072104 DOI: 10.1111/j.1471-4159.1991.tb03789.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Some effects of organophosphorus anticholinesterase compounds that are unrelated to cholinesterase inhibition and that are sometimes long lasting may be due to alterations at the cellular membrane level. Phosphatidylcholine exchange protein was used to assess the effects of sarin and soman on phosphatidylcholine asymmetry in the inner and outer leaflets of the plasma membrane bilayer of the electroplax. Exposure of electroplax (30 min in vitro) to soman (10(-4), 10(-6) M) or sarin (10(-4), 10(-6), 5 x 10(-9) M) increased the percentage of phosphatidylcholine in the outer monolayer of the innervated plasma membrane bilayer and decreased the percentage in the inner monolayer. These changes by sarin were observed at concentrations that produced 100% cholinesterase inhibition (10(-4), 10(-6) M) and at a concentration (5 x 10(-9) M) where no inhibition occurred, suggesting that these effects are not directly due to cholinesterase inhibition. A 1-week exposure of live eels to soman (10(-8) M) in vivo caused an increase in phosphatidylcholine labeling in the outer monolayer of the innervated and noninnervated surfaces of the electroplax. Two weeks after stopping exposure to soman, increased labeling was still observed, suggesting that this may be a long-term effect. Because the organophosphates did not increase the permeability of the electroplax, all of these changes in labeling appear to be due to a redistribution of phosphatidylcholine from the inner to the outer monolayer of the plasma membrane bilayer.
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Affiliation(s)
- C Supernovich
- Section of Pharmacology and Toxicology, School of Pharmacy, University of Connecticut, Storrs 06269
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Durieux I, Martel MB, Got R. Comparative effects of sulfhydryl reagents on membrane-bound and solubilized UDP-glucose:ceramide glucosyltransferase from Golgi membranes. Evidence for partial involvement of a thiol group in the nucleotide sugar binding site of the solubilized enzyme. Glycoconj J 1990. [DOI: 10.1007/bf01050379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Broekman MJ. Endogenous phosphatidylinositol 4,5-bisphosphate, phosphatidylinositol, and phosphatidic acid in stimulated human platelets. Methods Enzymol 1989; 169:415-30. [PMID: 2541313 DOI: 10.1016/0076-6879(89)69078-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Garg ML, Wierzbicki AA, Thomson AB, Clandinin MT. Dietary cholesterol and/or n-3 fatty acid modulate delta 9-desaturase activity in rat liver microsomes. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 962:330-6. [PMID: 2901857 DOI: 10.1016/0005-2760(88)90262-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
delta 9-Desaturase activity and fatty acid composition of liver microsomal phospholipids in rats fed diets enriched with either saturated (hydrogenated beef tallow) or alpha-linolenic (linseed oil) or eicosapentaenoic and docosahexaenoic (fish oil) acids with or without 2% cholesterol supplementation were investigated. Both the linseed oil and the fish oil diets inhibited delta 9-desaturase activity in the rat liver microsomes. The inhibition was greater when feeding fish oil (90%) compared with the linseed oil (60%) diet. Dietary cholesterol feeding accelerated conversion of palmitic (16:0) to palmitoleic (16:1) acid, irrespective of the fatty acid supplement. Feeding the linseed oil diet decreased, while feeding the fish oil diet increased synthesis of the monounsaturated fatty acids of n-7 series (palmitoleic and vaccenic acid) and decreased 18:1(n-9) in microsomal membrane lipids when compared with animals fed beef tallow. Addition of 2% cholesterol to the otherwise low cholesterol diets led to accumulation of 16:1(n-7), and 18:1(n-9) in microsomal membranes. These results suggest that delta 9-desaturase activity is dependent on the cholesterol contents as well as the n-3 fatty acid content of microsomal membranes on which it is localized.
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Affiliation(s)
- M L Garg
- Department of Foods and Nutrition, Faculty of Home Economics, University of Alberta, Edmonton, Canada
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Chalifour RJ, Spiro RG. Effect of phospholipids on thyroid oligosaccharyltransferase activity and orientation. Evaluation of structural determinants for stimulation of N-glycosylation. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(19)37640-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Garg ML, Keelan M, Thomson AB, Clandinin MT. Fatty acid desaturation in the intestinal mucosa. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 958:139-41. [PMID: 3334864 DOI: 10.1016/0005-2760(88)90256-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Information as to the ability of the enterocyte to desaturate fatty acids is lacking. This is important in understanding whether the source of intestinal arachidonic (20:4(n-6) acid is biliary or from de novo synthesis. Delta 9- and delta 6-desaturase enzymes were assayed in homogenates of rat jejunum, ileum and liver. Rat small intestine possesses desaturase activity to convert palmitic (16:0) to palmitoleic (16:1) and linoleic (18:2(n-6) to linolenic (18:3(n-6) acid. Enzyme activities were highest in liver relative to activity in jejunal and ileal homogenates. It is concluded that delta 9- and delta 6-desaturase activities may have an important role in determining physico-chemical properties and thus transport properties of enterocyte membranes.
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Affiliation(s)
- M L Garg
- Department of Foods and Nutrition, Faculty of Home Economics, University of Alberta, Edmonton, Canada
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Panagia V, Makino N, Ganguly PK, Dhalla NS. Inhibition of Na+-Ca2+ exchange in heart sarcolemmal vesicles by phosphatidylethanolamine N-methylation. EUROPEAN JOURNAL OF BIOCHEMISTRY 1987; 166:597-603. [PMID: 3609028 DOI: 10.1111/j.1432-1033.1987.tb13555.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The effect of phosphatidylethanolamine N-methylation on Na+-Ca2+ exchange was studied in sarcolemmal vesicles isolated from rat heart. Phosphatidylethanolamine N-methylation following incubation of membranes with S-adenosyl-L-methionine, a methyl donor for the enzymatic N-methylation, inhibited Nai+-dependent Ca2+ uptake by about 50%. The N-methylation reaction did not alter the passive permeability of the sarcolemmal vesicles to Na+ and Ca2+ and did not modify the electrogenic characteristics of the exchanger. The depressant effect of phosphatidylethanolamine N-methylation on Nai+-dependent Ca2+ uptake was prevented by S-adenosyl-L-homocysteine, an inhibitor of the N-methylation. Pretreatment of sarcolemma with methyl acetimidate hydrochloride, an amino-group-blocking agent, also prevented methylation-induced inhibition of Ca2+ uptake. In the presence of exogenous phospholipid substrate, the phospholipid N-methylation process in methyl-acetimidate-treated sarcolemmal vesicles was restored and the inhibitory effect on Ca2+ uptake was evident. These results suggest that phosphatidylethanolamine N-methylation influences the heart sarcolemmal Na+-Ca2+ exchange system.
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Pulido JA, del Hoyo N, Pérez-Albarsanz MA. Composition and fatty acid content of rat ventral prostate phospholipids. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 879:51-5. [PMID: 3768387 DOI: 10.1016/0005-2760(86)90265-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The major phospholipids of rat ventral prostate have been separated and examined using thin-layer chromatography, gas chromatography and mass spectrometry. The main phospholipid classes were choline and ethanolamine glycerophospholipids, accounting for 77.9% of total lipid phosphorus. The prostate also contained small amounts of serine glycerophospholipids and sphingomyelin. The relative proportions of fatty acids in the different phospholipid classes were also determined. Arachidonic acid in prostatic phospholipids is contributed primarily by ethanolamine glycerophospholipids. This fraction contained 65-69 mol% plasmalogens, whereas choline and serine glycerophospholipid fractions contained less than 5 mol% plasmalogens. Ethanolamine, choline and serine plasmalogens contained mainly vinyl ethers of palmitic and stearic aldehydes. Ethanolamine plasmalogens also contained the vinyl ether of oleic aldehyde.
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Gandhi CR, Ross DH. Phospholipid requirement of Ca2+-stimulated, Mg2+-dependent ATP hydrolysis in rat brain synaptic membranes. Neurochem Res 1986; 11:1447-62. [PMID: 2946970 DOI: 10.1007/bf00966224] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The phospholipid requirement for Ca2+-stimulated, Mg2+-dependent ATP hydrolysis (Ca2+/Mg2+-ATPase) and Mg2+-stimulated ATP hydrolysis (Mg2+-ATPase) in rat brain synaptosomal membranes was studied employing partial delipidation of the membranes with phospholipase A2 (Hog pancreas), phospholipase C (Bacillus cereus) and phospholipase D (cabbage). Treatment with phospholipase A2 caused an increase in the activities of both Ca2+/Mg2+-ATPase and Mg2+-ATPase whereas with phospholipase C treatment both the enzyme activities were inhibited. Phospholipase D treatment had no effect on Ca2+/Mg2+-ATPase but Mg2+-ATPase activity was inhibited. Inhibition of Mg2+-ATPase activity after phospholipase C treatment was relieved with the addition of phosphatidylinositol-4,5-bisphosphate (PIP2) and to a lesser extent with phosphatidylinositol-4-phosphate (PIP) and phosphatidylcholine (PC). Phosphatidylserine (PS), phosphatidic acid (PA), PIP and PIP2 brought about the reactivation of Ca2+/Mg2+-ATPase. Phosphatidylinositol (PI) and PA inhibited Mg2+-ATPase activity. Kms for Ca2+ (0.47 microM) and Mg2+ (60 microM) of the enzyme were found to be unaffected after treatment with the phospholipases.
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Negami AI, Sasaki H, Yamamura H. Activation of phosphorylase kinase through autophosphorylation by membrane component phospholipids. EUROPEAN JOURNAL OF BIOCHEMISTRY 1986; 157:597-603. [PMID: 3720745 DOI: 10.1111/j.1432-1033.1986.tb09707.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Phosphatidic acid (PtdOH) has been shown not only to stimulate autophosphorylation and autoactivation of phosphorylase kinase of rabbit skeletal muscle but also to decrease the apparent Ka for Ca2+ on autophosphorylation sharply [Negami et al. (1985) Biochem. Biophys. Res. Commun. 131, 712-719]. In this study we investigated the interaction between PtdOH and other phospholipids on autophosphorylation and autoactivation of this enzyme. Acidic phospholipids, such as phosphatidylserine (PtdSer), phosphatidylinositol (PtdIns) and PtdOH, stimulated this reaction about 2-4-fold, and the approximate Ka values of this reaction were 10 micrograms/ml, 6.3 micrograms/ml and 30 micrograms/ml respectively. The molar ratio of PtdIns and PtdSer with maximal effect on autophosphorylation was about 1:1. Under these conditions PtdOH stimulated the initial velocity of autophosphorylation about 5.2-fold. When fully autophosphorylated, about 12-13 mol phosphate per tetramer (alpha beta gamma delta) were incorporated in the presence of mixed acidic phospholipids (PtdOH:PtdIns:PtdSer = 2:1:1), which was about twice as much as values observed without effectors. In the presence of mixed acidic phospholipids there was a concomitant enhancement of kinase activity, about 30-40-fold at pH 6.8 and 2.5-3-fold at pH 8.2. Mixed acidic phospholipids sharply decreased an apparent Ka for Ca2+ from 4 X 10(-5) M to 8 X 10(-7) M. With mixed acidic phospholipids as effectors this autophosphorylation occurred through an intramolecular mechanism. Based on these results, autophosphorylation and autoactivation of phosphorylase kinase in the presence of acidic phospholipids may account for an important regulatory mechanism of glycogenolysis in muscle contraction.
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sn-1,2-Diacylglycerol kinase of Escherichia coli. Mixed micellar analysis of the phospholipid cofactor requirement and divalent cation dependence. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(19)84554-4] [Citation(s) in RCA: 117] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
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Panagia V, Okumura K, Makino N, Dhalla NS. Stimulation of Ca2+-pump in rat heart sarcolemma by phosphatidylethanolamine N-methylation. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 856:383-7. [PMID: 2937455 DOI: 10.1016/0005-2736(86)90049-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Incubation of purified cardiac sarcolemmal vesicles (SL) in the presence of S-adenosyl-L-methionine, a methyl donor for the enzymatic N-methylation of phosphatidylethanolamine (PE), increased the Ca2+-stimulated ATPase and ATP-dependent Ca2+ accumulation activities. Quantitative analysis of the methylated phospholipids revealed that maximal increase of Ca2+-pump activities was associated with predominant synthesis and intramembranal accumulation of phosphatidyl-N,N-dimethylethanolamine. The stimulation of SL Ca2+-pump activities was prevented by inhibitors of PE N-methylation such as S-adenosyl-L-homocysteine and methyl acetimidate hydrochloride. The results suggest a possible role of PE N-methylation in the regulation of Ca2+-transport across the heart SL membrane.
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Nelson DR, Hanahan DJ. Phospholipid and detergent effects on (Ca2+ + Mg2+)ATPase purified from human erythrocytes. Arch Biochem Biophys 1985; 236:720-30. [PMID: 3155927 DOI: 10.1016/0003-9861(85)90678-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
(Ca2+ + Mg2+)ATPase (EC 3.6.1.3) was solubilized from human erythrocyte membranes by detergent extraction with Triton N-101 (0.5 mg/mg membrane protein) and purified by calmodulin affinity chromatography. ATPase activity was assayed in mixtures of Triton N-101 and phospholipid, without reconstitution into bilayer vesicles. At low levels of phospholipid (5 micrograms/ml), the ATPase activity was highly sensitive to the detergent concentration, with maximal activity occurring at or near the critical micelle concentration of the detergent. With increased amounts of phospholipid (50 micrograms/ml), detergent concentrations greater than the critical micelle concentration were required for maximal activity. Detergent alone did not support ATPase activity. Sonicated phospholipid in the form of vesicles was equally ineffective. Activity seemed to be dependent on the presence of detergent/phospholipid mixed micelles. The acidic phospholipids, phosphatidylserine and phosphatidylinositol, as well as the commercial phospholipid preparation, Asolectin, gave activities five to eight times greater than the same amount of phosphatidylcholine. Mixtures of phosphatidylserine and phosphatidylcholine produced intermediate ATPase activities, with the maximal value dependent on the phosphatidylserine concentration. Addition of phosphatidylcholine to fixed concentrations of phosphatidylserine caused a rise in activity that was independent of the ratio of the two phospholipids or the total phospholipid concentration. Phosphatidylcholine may therefore be irreplaceable for some aspect of ATPase function. The number of phospholipid molecules present in mixed micelles at maximal ATPase activity was calculated to be near 50. This value implied that the hydrophobic surface of the ATPase molecule must be completely coated by a single layer of phospholipid molecules for maximum activity to occur.
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