Biomaterial Database

Influence of alpha-tocopherol incorporation on Ca(2+)-induced fusion of phosphatidylserine vesicles. 1996

F J Aranda, and M P Sánchez-Migallón, and J C Gómez-Fernández

Departamento de Bioquímica y Biología Molecular A, Facultad de Veterinaria, Universidad de Murcia, Spain.

The effect of alpha-tocopherol on the Ca(2+)-induced fusion of large unilamellar phosphatidylserine vesicles has been investigated. Mixing of aqueous vesicle contents was followed continually with the terbium-dipicolinic acid (Tb-DPA) assay, while the dissociation of preencapsulated Tb-DPA complex was taken as a measure of the release of vesicle contents. Vesicles consisting of pure phosphatidylserine and phosphatidylserine containing 2, 5, and 10 mol% of alpha-tocopherol were employed at different Ca2+ concentrations. The presence of low amounts of alpha-tocopherol decreased the initial rate of fusion without changing the Ca2+ threshold concentration. The reduction of the initial rate of fusion was proportional to the amount of alpha-tocopherol present in the bilayer. An alpha-tocopherol concentration-dependent decrease of both the initial rate and the final extent of release of vesicle contents was also observed. This effect was more evident as more alpha-tocopherol was incorporated in the bilayer, so that in the presence of 10 mol% of alpha-tocopherol no significant release was observed after 5 min. The stabilization of the vesicular structure exerted by alpha-tocopherol was responsible for the apparent increase of the fluorescence intensity of the Tb-DPA complex at later stages of the process. The results reflect a perturbation of the membrane by low concentrations of alpha-tocopherol which may account for a number of biological effects of this vitamin, not related to its antioxidant role.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008081	Liposomes	Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.	Niosomes,Transferosomes,Ultradeformable Liposomes,Liposomes, Ultra-deformable,Liposome,Liposome, Ultra-deformable,Liposome, Ultradeformable,Liposomes, Ultra deformable,Liposomes, Ultradeformable,Niosome,Transferosome,Ultra-deformable Liposome,Ultra-deformable Liposomes,Ultradeformable Liposome
D008561	Membrane Fusion	The adherence and merging of cell membranes, intracellular membranes, or artificial membranes to each other or to viruses, parasites, or interstitial particles through a variety of chemical and physical processes.	Fusion, Membrane,Fusions, Membrane,Membrane Fusions
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D010718	Phosphatidylserines	Derivatives of PHOSPHATIDIC ACIDS in which the phosphoric acid is bound in ester linkage to a SERINE moiety.	Serine Phosphoglycerides,Phosphatidyl Serine,Phosphatidyl Serines,Phosphatidylserine,Phosphoglycerides, Serine,Serine, Phosphatidyl,Serines, Phosphatidyl
D010848	Picolinic Acids	Compounds with general formula C5H4N(CO2H) derived from PYRIDINE, having a carboxylic acid substituent at the 2-position.	Acids, Picolinic
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D013725	Terbium	An element of the rare earth family of metals. It has the atomic symbol Tb, atomic number 65, and atomic weight 158.92.
D014810	Vitamin E	A generic descriptor for all TOCOPHEROLS and TOCOTRIENOLS that exhibit ALPHA-TOCOPHEROL activity. By virtue of the phenolic hydrogen on the 2H-1-benzopyran-6-ol nucleus, these compounds exhibit varying degree of antioxidant activity, depending on the site and number of methyl groups and the type of ISOPRENOIDS.