Phospholipid mixtures, metallization formed from

Metallization of Polymerized Vesicles Formed from Mixtures of Zwitterlonic and Negatively Charged Phospholipids... 

The first approach in using vesicle membranes in nanoparticle synthesis was to polymerize vesicles formed from 9 1 and 1 1 mixtures of 1 and 2 in the presence of Pd(NH3)4Cl2. Palladium ions bound to negatively charged phospholipids in bilayer membranes had been previously demonstrated to serve as catalytic sites for electroless metallization (47). Light scattering revealed that bimodal populations of vesicles were formed both from the 9 1 (31 + 15 nm and 114 + 40 nm) and 1 1 (38 + 13 nm and 109 + 41 nm) mixtures. Exposure of the vesicles to UV radiation (254 nm) resulted in the reaction of 33 % + 6% of the lipid monomer when 10 % of 2 was present and 50% + 4% for vesicles containing 50% 2. The differences in the amount of reaction of monomer are probably due to both ion and pH effects. Non-cross linked polymerized vesicle membranes consist of many individual... 

Agonists - The existence of two receptor populations for histamine raises the interesting question of whether the chemical mechanism of histamine interaction differs between the two receptor types. Some indications of the chemical properties which may differentiate receptor action come from studies of histamine chemistry and from structure-activity considerations of congeners. Histamine in aqueous solution is a mixture of equilibrating species, viz. ionic forms, tautomers and conformers nmr studies confirm earlier pK work indicating a N -H N -H (structures 1 and 2) tautomer ratio of approximately 4 1 for histamine monocation, and a comparable ratio for histamine base. The latter result contrasts with crystal structure data and molecular orbital predictions, and may indicate an influence of solvent on tautomer stability. Recent studies of properties pertinent to consideration of ligand-receptor interactions are conformation (MO calculations and infra-red comparison of solid state and chloroform solutions of histamine base ), electronic charge distribution, metal complexation, and phospholipid inter-... 

Therefore, to understand the behavior of food emulsions, we need to know as much as possible about these types of emulsifiers, because fliey may not behave exactly similarly to classical small-molecule emulsifiers. For example, phospholipid molecules can interact with each other to form lamellar phases or vesicles they may interact with neutral lipids to form a mono- or multi-layer around the lipid droplets, or they may interact with proteins which are either adsorbed or free in solution. Any or all of these interactions may occur in one food emulsion. The properties of the emulsion system depend on which behavior pattern predominates. Unfortunately for those who have to formulate food emulsions, it is rarely possible to consider the emulsion simply as oil coated with one or a mixture of surfactants. Almost always there are other components whose properties need to be considered along with those of the emulsion droplets themselves. For example, various metal salts may be included in the formulation (e.g. Ca " is nearly always present in food products derived from milk ingredients), and there may also be hydrocolloids present to increase the viscosity or yield stress of the continuous phase to delay or prevent creaming of the emulsion. In addition, it is very often the case, in emulsions formulated using proteins, that some of the protein is free in solution, having either not adsorbed at all or been displaced by other surfactants. Any of these materials (especially the metal salts and the proteins) may interact with the molecules... 

Schiff base compounds formed by the interaction of oxidation products with proteins, phospholipids and nucleic acids produce chromophores showing characteristic fluorescence spectra. The Schiff base formed between malonaldehyde and amino acids is attributed to the conjugated structure -NH=CH-CH=CH-NH-. Lipid-soluble fluorescence chromophores are produced from oxidized phospholipids and from oxidized fatty acid esters in the presence of phospholipids. These chromophores have fluorescence emission maxima at 435-440 nm and excitation maxima at 365 nm. The Schiff base of malonaldehyde and phospholipids has a higher wavelength maximum for emission (475 nm) and excitation (400 nm). The interaction between oxidized arachidonic acid and dipalmityl phosphatidylethanolamine produce similar fluorescence spectra (maximum excitation at 360-90 nm and maximum emission at 430-460 nm). The products from oxidized arachidonic acid and DNA have characteristic fluorescence spectra, with excitation maximum at 315 nm and emission maximum at 325 nm. Similar fluorescence spectra, with excitation maximum at 320 mn and emission maximum at420 nm, are obtained from the interactions of either lipid hydroperoxides or secondary oxidation products with DNA in the presence of metals and reducing agents, or different aldehydes, ketones and dimeric compounds from oxidized linolenate. Therefore, the Schiff base produced from various oxidized lipids and phospholipids and DNA may be considered to be due to a mixture of closely related chromophores. 

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