Dimyristoyl Phosphatidylcholine: A Remarkable Exception to α-Tocopherol’s Membrane Presence

2013 ◽  
Vol 136 (1) ◽  
pp. 203-210 ◽  
Author(s):  
Drew Marquardt ◽  
Justin A. Williams ◽  
Jacob J. Kinnun ◽  
Norbert Kučerka ◽  
Jeffrey Atkinson ◽  
...  
Keyword(s):  
Dimyristoyl Phosphatidylcholine

The biological activity of glucagon–phospholipid complexes

1983 ◽  
Vol 61 (7) ◽  
pp. 688-691 ◽  
Author(s):  
J. J. Liepnieks ◽  
P. Stoskopf ◽  
E. A. Carrey ◽  
C. Prosser ◽  
R. M. Epand
Keyword(s):  
Biological Activity ◽  
Adenylate Cyclase ◽  
Plasma Membranes ◽  
Bovine Brain ◽  
Water Soluble ◽  
Dipalmitoyl Phosphatidylcholine ◽  
Dimyristoyl Phosphatidylcholine ◽  
Lipoprotein Complex ◽  
Stimulation Of

Glucagon can form water-soluble complexes with phospholipids. The incorporation of glucagon into these lipoprotein particles reduces the biological activity of the hormone. The effect is observed only at temperatures below the phase transition temperature of the phospholipid and results in a decreased stimulation of the adenylate cyclase of rat liver plasma membranes by the lipoprotein complex as compared with the hormone in free solution. Two- to five-fold higher concentrations of glucagon are required for half-maximal stimulation of adenylate cyclase when the hormone is complexed with dimyristoyl phosphatidylcholine, dipalmitoyl phosphatidylcholine, or bovine brain sphingomyelin. A possible role of lipoprotein-associated hormones in the development of insulin resistance is discussed.

scholarly journals Release of the glycosylphosphatidylinositol-anchored enzyme ecto-5′-nucleotidase by phospholipase C: catalytic activation and modulation by the lipid bilayer

1998 ◽  
Vol 332 (1) ◽  
pp. 101-109 ◽  
Author(s):  
Marty T. LEHTO ◽  
Frances J. SHAROM
Keyword(s):  
Plasma Membrane ◽  
Phospholipase C ◽  
Lipid Bilayer ◽  
Hydrolytic Enzymes ◽  
Detergent Solution ◽  
Gpi Anchor ◽  
Rich Mixture ◽  
Catalytic Activation ◽  
Dimyristoyl Phosphatidylcholine ◽  
Native Plasma

Many hydrolytic enzymes are attached to the extracellular face of the plasma membrane of eukaryotic cells by a glycosylphosphatidylinositol (GPI) anchor. Little is currently known about the consequences for enzyme function of anchor cleavage by phosphatidylinositol-specific phospholipase C. We have examined this question for the GPI-anchored protein 5´-nucleotidase (5´-ribonucleotide phosphohydrolase; EC 3.1.3.5), both in the native lymphocyte plasma membrane, and following purification and reconstitution into defined lipid bilayer vesicles, using Bacillus thuringiensis phosphatidylinositol-specific phospholipase C (PI-PLC). Membrane-bound, detergent-solubilized and cleaved 5´-nucleotidase all obeyed Michaelis–Menten kinetics, with a Km for 5´-AMP in the range 11–16 µM. The GPI anchor was removed from essentially all 5´-nucleotidase molecules, indicating that there is no phospholipase-resistant pool of enzyme. However, the phospholipase was much less efficient at cleaving the GPI anchor when 5´-nucleotidase was present in detergent solution, dimyristoyl phosphatidylcholine, egg phosphatidylethanolamine and sphingomyelin, compared with the native plasma membrane, egg phosphatidylcholine and a sphingolipid/cholesterol-rich mixture. Lipid molecular properties and bilayer packing may affect the ability of PI-PLC to gain access to the GPI anchor. Catalytic activation, characterized by an increase in Vmax, was observed following PI-PLC cleavage of reconstituted 5´-nucleotidase from vesicles of several different lipids. The highest degree of activation was noted for 5´-nucleotidase in egg phosphatidylethanolamine. An increase in Vmax was also noted for a sphingolipid/cholesterol-rich mixture, the native plasma membrane and egg phosphatidylcholine, whereas vesicles of sphingomyelin and dimyristoyl phosphatidylcholine showed little activation. Km generally remained unchanged following cleavage, except in the case of the sphingolipid/cholesterol-rich mixture. Insertion of the GPI anchor into a lipid bilayer appears to reduce the catalytic efficiency of 5´-nucleotidase, possibly via a conformational change in the enzyme, and activity is restored on release from the membrane.

Fusion kinetics of dimyristoyl phosphatidylcholine vesicles around the phase transition of the aliphatic chains

Biochimie ◽  
1982 ◽  
Vol 63 (11-12) ◽  
pp. 955-959 ◽  
Author(s):  
Didier Sornette ◽  
Christine Hesse-Bezot ◽  
Nicole Ostrowsky
Keyword(s):  
Phase Transition ◽  
Dimyristoyl Phosphatidylcholine ◽  
Kinetics Of ◽  
Aliphatic Chains

scholarly journals Interaction of cytochrome b5 with surfactant vesicles

1988 ◽  
Vol 251 (2) ◽  
pp. 391-396
Author(s):  
D M Davies ◽  
J M Lawther
Keyword(s):  
Absorption Spectrum ◽  
Phosphatidic Acid ◽  
Cytochrome B5 ◽  
Visible Absorption Spectrum ◽  
Visible Absorption ◽  
Surfactant Vesicles ◽  
Dimyristoyl Phosphatidylcholine ◽  
Dicetyl Phosphate ◽  
Kinetics Of

Changes in the u.v.-visible absorption spectrum of cytochrome b5 which occur upon addition of dicetyl phosphate, dimyristoyl phosphatidic acid (DMPA), or mixed DMPA/dimyristoyl phosphatidylcholine vesicles are consistent with haem transfer from the cytochrome to the membrane via an intermediate haemoprotein species. The effects of vesicle charge and concentration on the kinetics of haem transfer are discussed.

Transport of Ca2+ by diltiazem across the lipid bilayer in model liposomes

1992 ◽  
Vol 70 (7) ◽  
pp. 608-612 ◽  
Author(s):  
Vettai S. Ananthanarayanan ◽  
Lorne B. Taylor ◽  
Samuel Pirritano
Keyword(s):  
Ion Transport ◽  
Calcium Channel ◽  
Liquid Crystalline ◽  
Lipid Membrane ◽  
Nonpolar Lipid ◽  
Fluorescent Indicators ◽  
Related Data ◽  
Carrier Mechanism ◽  
Dimyristoyl Phosphatidylcholine ◽  
Drug Complex

The calcium channel antagonist diltiazem was examined for its ability to translocate Ca2+ from an aqueous medium to the nonpolar lipid milieu. We monitored the spectral changes caused by the drug-mediated cation transport at 37 °C in unilamellar vesicles made of dimyristoyl phosphatidylcholine (DMPC) and containing the calcium-sensitive dye arsenazo III trapped inside. Vesicle leakage or membrane fusion caused by diltiazem was assessed by the use of vesicles containing fluorescent indicators. These effects were, however, found to be insignificant compared with ion transport. The transport was negligible at temperatures below the liquid crystalline to gel transition temperature of DMPC indicating a carrier mechanism of ion transport. A quantitative analysis of the transport kinetics indicated that a 1:2 Ca +-drug complex is formed inside the lipid. The calcium ionophoretic ability of diltiazem, combined with other related data, suggests a possible role for Ca2+ in the conformation of the drug in the lipid membrane milieu and in its interaction with the calcium channel.Key words: calcium channel antagonists, diltiazem, Ca2+ ionophore, liposomes, drug-Ca2+ complex.

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