Biomaterial Database

Extension of the parallax analysis of membrane penetration depth to the polar region of model membranes: use of fluorescence quenching by a spin-label attached to the phospholipid polar headgroup. 1993

F S Abrams, and E London

Department of Biochemistry and Cell Biology, State University of New York at Stony Brook 11794-5215.

The parallax method is a method by which the depth of fluorescent molecules within a membrane is calculated from the ratio of quenching induced by two spin-labeled phospholipids at different depths. In this report, the method is extended to measurements of depth in the polar headgroup region of the membrane through use of a lipid with a spin-label attached to the polar choline moiety. Quenching data indicate that the choline-attached nitroxide is close to 19.5 A from the bilayer center, in good agreement with the choline location previously determined by diffraction measurements. By using quenching results obtained with this polar headgroup-labeled phospholipid, depths more accurate than those measured previously can be obtained for fluorophores in the polar region of the membrane. It appears that the most reliable results are obtained when depth is calculated from the quenching of the two spin-labels that quench a specific fluorophore most strongly. Applying this approach to a series of anthroyloxy-labeled fatty acids indicates that the depth of the anthroyloxy group is almost linearly related to the number of carbon atoms between it and the carboxyl group. The fatty acid carboxyl group itself is close to 18.6 A from the bilayer center in the ionized form and 16 A from bilayer center in the protonated form. This is close to the depth of the carboxyl groups on phospholipid fatty acyl chains. More accurate depths have also been obtained for 7-nitro-2,1,3-benzoxadiazol-4-yl (NBD) labeled phospholipids using the quenching of the choline-attached spin-label.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D008051	Lipid Bilayers	Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.	Bilayers, Lipid,Bilayer, Lipid,Lipid Bilayer
D008566	Membranes	Thin layers of tissue which cover parts of the body, separate adjacent cavities, or connect adjacent structures.	Membrane Tissue,Membrane,Membrane Tissues,Tissue, Membrane,Tissues, Membrane
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
D008961	Models, Structural	A representation, generally small in scale, to show the structure, construction, or appearance of something. (From Random House Unabridged Dictionary, 2d ed)	Model, Structural,Structural Model,Structural Models
D008968	Molecular Conformation	The characteristic three-dimensional shape of a molecule.	Molecular Configuration,3D Molecular Structure,Configuration, Molecular,Molecular Structure, Three Dimensional,Three Dimensional Molecular Structure,3D Molecular Structures,Configurations, Molecular,Conformation, Molecular,Conformations, Molecular,Molecular Configurations,Molecular Conformations,Molecular Structure, 3D,Molecular Structures, 3D,Structure, 3D Molecular,Structures, 3D Molecular
D009327	4-Chloro-7-nitrobenzofurazan	A benzofuran derivative used as a protein reagent since the terminal N-NBD-protein conjugate possesses interesting fluorescence and spectral properties. It has also been used as a covalent inhibitor of both beef heart mitochondrial ATPase and bacterial ATPase.	Chloronitrobenzoxadiazole,NBD Chloride,7-Chloro-4-nitrobenzofurazan,NBF-Cl,Nitrobenzoxadiazole Chloride,4 Chloro 7 nitrobenzofurazan,7 Chloro 4 nitrobenzofurazan,Chloride, NBD,Chloride, Nitrobenzoxadiazole,NBF Cl
D010713	Phosphatidylcholines	Derivatives of PHOSPHATIDIC ACIDS in which the phosphoric acid is bound in ester linkage to a CHOLINE moiety.	Choline Phosphoglycerides,Choline Glycerophospholipids,Phosphatidyl Choline,Phosphatidyl Cholines,Phosphatidylcholine,Choline, Phosphatidyl,Cholines, Phosphatidyl,Glycerophospholipids, Choline,Phosphoglycerides, Choline
D010714	Phosphatidylethanolamines	Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to an ethanolamine moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and ethanolamine and 2 moles of fatty acids.	Cephalin,Cephalins,Ethanolamine Phosphoglyceride,Ethanolamine Phosphoglycerides,Ethanolamineglycerophospholipids,Phosphoglyceride, Ethanolamine,Phosphoglycerides, Ethanolamine
D005456	Fluorescent Dyes	Chemicals that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.	Flourescent Agent,Fluorescent Dye,Fluorescent Probe,Fluorescent Probes,Fluorochrome,Fluorochromes,Fluorogenic Substrates,Fluorescence Agents,Fluorescent Agents,Fluorogenic Substrate,Agents, Fluorescence,Agents, Fluorescent,Dyes, Fluorescent,Probes, Fluorescent,Substrates, Fluorogenic
D013113	Spin Labels	Molecules which contain an atom or a group of atoms exhibiting an unpaired electron spin that can be detected by electron spin resonance spectroscopy and can be bonded to another molecule. (McGraw-Hill Dictionary of Chemical and Technical Terms, 4th ed)	Spin Label,Label, Spin,Labels, Spin