Effects of Temperature and Glycerides on the Enhancement of Agkistrodon piscivorus piscivorus Phospholipase A2 Activity by Lysolecithin and Palmitic Acid

Bell, John D.; Baker, Marilyn L.; Bent, E; Ashton, Rendell W.; Hemming, Daniel J. B.; Hansen, Lee D.

doi:10.1021/bi00036a031

Cited by 33 publications

(67 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…12). Importantly, these results support the concept that principles learned from biophysical studies with artificial membranes apply to biological systems (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). Attempts have been made previously with cultured cells to determine whether changes in membrane order detectable with fluorescent probes might explain the action of Ca 2ϩ to render them vulnerable to sPLA 2 (3,4).…”

Section: Discussionsupporting

confidence: 75%

Mechanisms by Which Intracellular Calcium Induces Susceptibility to Secretory Phospholipase A2 in Human Erythrocytes

Smith

Farnbach

Harris

et al. 2001

Journal of Biological Chemistry

Self Cite

118

View full text Add to dashboard Cite

Exposure of human erythrocytes to the calcium ionophore ionomycin rendered them susceptible to the action of secretory phospholipase A 2 (sPLA 2 ). Analysis of erythrocyte phospholipid metabolism by thin-layer chromatography revealed significant hydrolysis of both phosphatidylcholine and phosphatidylethanolamine during incubation with ionomycin and sPLA 2 . Several possible mechanisms for the effect of ionomycin were considered. Involvement of intracellular phospholipases A 2 was excluded since inhibitors of these enzymes had no effect. Assessment of membrane oxidation by cis-parinaric acid fluorescence and comparison to the oxidants diamide and phenylhydrazine revealed that oxidation does not participate in the effect of ionomycin. Incubation with ionomycin caused classical physical changes to the erythrocyte membrane such as morphological alterations (spherocytosis), translocation of aminophospholipids to the outer leaflet of the membrane, and release of microvesicles. Experiments with phenylhydrazine, KCl, quinine, merocyanine 540, the calpain inhibitor E-64d, and the scramblase inhibitor R5421 revealed that neither phospholipid translocation nor vesicle release was required to induce susceptibility. Results from fluorescence spectroscopy and two-photon excitation scanning microscopy using the membrane probe laurdan argued that susceptibility to sPLA 2 is a consequence of increased order of membrane lipids.Under normal conditions, healthy cell membranes resist catalysis by secretory phospholipase A 2 (sPLA 2 ) 1 (1-4). However, they may become susceptible under circumstances that cause alteration of membrane physical properties (1-4). Previous studies using artificial membranes demonstrated that alterations that increase susceptibility generally increase the anionic charge of the outer leaflet, increase bilayer curvature, and/or decrease interactions among neighboring phospholipids (5-9). In some cases, enhanced susceptibility of artificial membranes depends on an increase in the order of the phospholipids (8, 10 -14). These changes increase susceptibility by augmenting the binding of sPLA 2 and/or by improving access of membrane phospholipids to the active site of the enzyme (5-12, 15, 16).It is not known whether the properties that induce susceptibility to sPLA 2 in artificial membranes also contribute to the vulnerability of biological membranes to attack by the enzyme. In order to address this issue, we manipulated various properties of erythrocyte membranes by preparing different types of ghosts as explained in the accompanying particle (17). We found that the factors that determined the degree of susceptibility were increased exposure of phosphatidylserine, an anionic phospholipid, and increased membrane order. These interpretations agreed with those from studies of susceptibility using artificial membranes (5-16). The next question, then, is whether these same factors are important in the hydrolysis of intact cells by sPLA 2 under conditions at which they have become susceptible such as in the presence...

show abstract

Section: Discussionsupporting

confidence: 75%

Mechanisms by Which Intracellular Calcium Induces Susceptibility to Secretory Phospholipase A2 in Human Erythrocytes

Smith

Farnbach

Harris

et al. 2001

Journal of Biological Chemistry

Self Cite

118

View full text Add to dashboard Cite

show abstract

“…For example, small vesicles composed of phosphatidylcholine are immediately hydrolyzed upon addition of sPLA 2 , while larger vesicles are only vulnerable after perturbation of the membrane with contaminants (8,9,14,15,37). Both gross (size and distortion of shape) and fine (surface texture) morphology were scored from micrographs such as those shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Second, changes in membrane physical properties that promote one or both of these events render the membrane more susceptible to catalysis (8 -10, 14 -17). The properties found to be important for inducing susceptibility can be summarized in two categories: those that promote negative charge at the bilayer surface and those that perturb the interactions among phospholipid molecules (9,10,(13)(14)(15)(16)(17).…”

Section: Discussionmentioning

confidence: 99%

“…However, the assumption that fluid lipids would be hydrolyzed more readily than ordered lipids is an oversimplification not supported by data obtained with artificial membranes. For example, bilayers composed of pure phosphatidylcholine are most vulnerable to attack when the membrane is in a state intermediate between fluid and ordered, such as that observed at the membrane phase transition temperature (9,14,17). Therefore, if the membrane is fluid, lowering the temperature to make it more ordered can improve susceptibility.…”

Section: Discussionmentioning

confidence: 99%

“…Two examples are fatty acid and diacylglycerol. In both cases, the addition of the contaminant causes the membrane to become more ordered under conditions at which hydrolysis is promoted (9,14,15). It could be argued that the effect of the fatty acid to promote hydrolysis is due to its negative charge; however, it is equally or more effective at making the membrane susceptible when in the protonated (non-charged) form (15).…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Physical Properties of Erythrocyte Ghosts That Determine Susceptibility to Secretory Phospholipase A2

Harris

Smith

Bell

2001

Journal of Biological Chemistry

Self Cite

View full text Add to dashboard Cite

Artificial membranes may be resistant or susceptible to catalytic attack by secretory phospholipase A 2 (sPLA 2 ) depending on the physical properties of the membrane. Living cells are normally resistant but become susceptible during trauma, apoptosis, and/or a significant elevation of intracellular calcium. Intact erythrocytes and ghosts were studied to determine whether the principles learned from artificial systems apply to biological membranes. Membrane properties such as phospholipid and/or protein composition, morphology, and microscopic characteristics (e.g. fluidity) were manipulated by preparing ghosts under different experimental conditions such as in the presence or absence of divalent cations with or without ATP. The properties of each membrane preparation were assessed by biochemical and physical means (fluorescence spectroscopy and electron and two-photon microscopy using the membrane probes bis-pyrene and laurdan) and compared with sPLA 2 activity. The properties that appeared most relevant were the degree of phosphatidylserine exposure on the outer face of the membrane and changes to the membrane physical state detected by bis-pyrene and laurdan. Specifically, vulnerability to hydrolysis by sPLA 2 was associated with an increase in bilayer order apparently reflective of expansion of membrane regions of diminished fluidity. These results argue that the general principles identified from studies with artificial membranes apply to biological systems.

show abstract

Ca2+-Induced Phase Separation in the Membrane of Palmitate-Containing Liposomes and Its Possible Relation to Membrane Permeabilization

et al. 2007

View full text Add to dashboard Cite

A Ca(2+)-induced phase separation of palmitic acid (PA) in the membrane of azolectin unilamellar liposomes has been demonstrated with the fluorescent membrane probe nonyl acridine orange (NAO). It has been shown that NAO, whose fluorescence in liposomal membranes is quenched in a concentration-dependent way, can be used to monitor changes in the volume of lipid phase. The incorporation of PA into NAO-labeled liposomes increased fluorescence corresponding to the expansion of membrane. After subsequent addition of Ca(2+), fluorescence decreased, which indicated separation of PA/Ca(2+) complexes into distinct membrane domains. The Ca(2+)-induced phase separation of PA was further studied in relation to membrane permeabilization caused by Ca(2+) in the PA-containing liposomes. A supposition was made that the mechanism of PA/Ca(2+)-induced membrane permeabilization relates to the initial stage of Ca(2+)-induced phase separation of PA and can be considered as formation of fast-tightening lipid pores due to chemotropic phase transition in the lipid bilayer.

show abstract

Effects of Temperature and Glycerides on the Enhancement of Agkistrodon piscivorus piscivorus Phospholipase A2 Activity by Lysolecithin and Palmitic Acid

Cited by 33 publications

References 50 publications

Mechanisms by Which Intracellular Calcium Induces Susceptibility to Secretory Phospholipase A2 in Human Erythrocytes

Mechanisms by Which Intracellular Calcium Induces Susceptibility to Secretory Phospholipase A2 in Human Erythrocytes

Physical Properties of Erythrocyte Ghosts That Determine Susceptibility to Secretory Phospholipase A2

Ca2+-Induced Phase Separation in the Membrane of Palmitate-Containing Liposomes and Its Possible Relation to Membrane Permeabilization

Contact Info

Product

Resources

About