Lipids solvents

The other anomalous behavior was the smaller-than-expected permeability of highly branched compounds. This deviation has been explained on the basis that membrane lipids are subject to a more highly constrained orientation (probably a parallel configuration of hydrocarbon chains of fatty acids) than are those in a bulk lipid solvent. As a result, branched compounds must disrupt this local lipid structure of the membrane and will encounter greater steric hindrance than will a straight-chain molecule. This effect with branched compounds is not adequately reflected in simple aqueous-lipid partitioning studies (i.e., in the K0/w value). 

Greiff [3.25] classified the virus into five categories 1, Nucleic acid type (either DNA-core or RNA-core) 2, sensitivity against lipid solvents 3, envelope about the nucleocapsid or not (naked) 4, pH sensitivity, exposure to pH 3 for 30 min differentiates between those viruses, which lose more than a decade in titer and those which lose no titer or less than one decade 5, heat-sensitive virus cannot be exposed to +50 °C for 30 min. 

Figure 7.2 Partial capillary gas chromatogram displaying the principal lipid solvent soluble constituents of a black tarry deposit on the surface of a Neolithic potsherd from Ergolding Fischergasse, Bavaria, Germany. The sample was trimethylsilylated prior to GC (for further details see Heron et al., 1997). Peak identities (confirmed by GC-MS analysis) 1, lupenone 2, lupeol 3, betulin 4, betulinic acid.

If the virus is treated with proteolytic enzymes the fuzzy layer formed by the viral spikes is removed (Osterrieth, 1965 Compans, 1971 Gahm-berg et al, 1972 Sefton and Gaffney, 1974 Utermann and Simons, 1974). Remnants of both El and E2 are left in the bilayer. These have a hydrophobic amino acid composition, and are soluble in lipid solvents such as chloroform-methanol. The amphiphilic nature of the spike protein is also evident from its capacity to bind Triton X-100 (0.6 g/g protein) which binds to the hydrophobic part to form a water-soluble protein-detergent complex (Simons et al., 1973a). The ability of amphiphilic proteins to bind Triton can be used to separate them from hydrophilic proteins using an extraction procedure recendy described... 

Lupulescu AP, Birmingham DJ. 1975. Effect of lipid solvents on protein, DNA, and collagen synthesis in human skin An electron microscopic autoradiographic study. J Invest Dermatol 65(5) 419-422. 

Lupulescu AP, Birmingham DJ. 1976. Effect of protective agent against lipid-solvent-induced damages Ultrastructural and scanning electron microscopial study of human epidermis. Arch Environ Health 31(l) 33-36. 

The temperature, abbreviated c.m.t., at which a deter-gent/solvent system or a lipid/solvent system passes from a hydrated crystalline state to an isotropic micellar solution. For a number of lipids, the c.m.t. is below the freezing point of the solvent. The Krafft point,, is the c.m.t. at the critical micelle concentration. 

It should be noted that all three are lethal, however, and so the acute toxicity of these compounds is not entirely due to C-40 substituent effects. Potency does follow the oxidation series from alcohol to aldehyde to acid vivo, suggesting that perhaps these substituents influence the degree of accessibility of each lipid-solvent soluble toxin to its membrane site of action. Being that the toxins in their natural forms are so soluble in non-polar solvents, and tend to bind to or solubilize in the lipid components of membrane... 

Many cell walls have layers in the outer regions of the wall that carry lipid material. These are cutin, suberin, and waxes (67). How these are transported to the outside of the cell wall is not known. Pores have not been found, nor has a volatile lipid solvent been detected that would carry the lipid through the hydrophilic wall. 

The heterogeneous class of compounds marked by solubility in so-called lipid solvents (acetone, hydrocarbons, ether, etc.) and relative insolubility in water, has traditionally been called lipids (3). This historical classification, based upon isolation procedures from natural products, is obviously too broad for simple generalizations since it includes triglycerides, fatty acids, phospholipids, sterols, sterol esters, bile acids, waxes, hydrocarbons, fatty ethers and hydrocarbons. For the purposes of this chapter, we will consider lipids to be fatty acids and their derivatives. 

J Folch et al, J. Biol. Chem. 226, 497-509 (1957) Use of chloroform-methanol as i lipid solvent... 

Ohshima, T., Ratnayake, W.M.N., and Ackman, R.G. 1987. Cod lipids, solvent systems and the effect of fatty acid chain length and unsaturation on lipid class analysis by Iatroscan TLC-FID. J. Am. Oil Chem. Soc. 64 219-223. 

Low-wavelength UV detection (200-210 nm) is more sensitive and permits the use of gradients but precludes the use of certain common lipid solvents, such as chloroform and acetone, which are opaque in the UV region of interest. With low-wavelength UV detection, the response will also be somewhat dependent on fatty acid composition. For these reasons the mobile phases used in lipid analysis by HPLC may seem rather strange to workers familiar with the Thin Layer Chromatography (TLC) or open column separations. 

A second physicochemical parameter influencing chemical penetration through membranes is the relative lipid solubility of the potential toxicant that can be ascertained from its known partition coefficient. The partition coefficient is a measure of the ability of a chemical to separate between two immiscible phases. The phases consist of an organic phase (e.g., octanol or heptane) and an aqueous phase (e.g., water). The lipid solvent used for measurement is usually octanol because it best mimics the carbon chain of phospholipids, but many other systems have been reported (chloroform/water, ether/water, olive oil/water). The lipid solubility and the water solubility characteristics of the chemical will allow it to proportionately partition between the organic and water phase. The partition coefficients can be calculated using the following equation ... 

All of the chloroethanes produce physiologic symptoms characteristics of chloro-organics and lipid solvents CNS depression (intoxication), abnormal weakness, restlessness and irregular respiration, Incoordination and unconsciousness. 

Fig. 7 Membranes can be formed by components of carbonaceous meteorites [69,70]. a The Murchison meteorite contains approximately 2% organic carbon by weight, b Organic compounds can be extracted from the meteorite by a lipid solvent system (chloroform-methanol), then separated by two-dimensional chromatography. Polycyclic compounds in the mixture produce fluorescent spots, c The organic acid fraction from the TLC plate readily assembles into membranous vesicles when exposed to dilute aqueous solutions buffered at pH 8-9. The vesicles were photographed by their autofluorescence. Scale bar shows 20 im...

The molar ratios of most of the amino acids in the protein of the German cockroach are generally similar to those of vertebrates and other invertebrates with respect to whole animal protein hydrolyzates (1). However, histidine, lysine, tyrosine, leucine, isoleucine, valine, and alanine are somewhat more abundant in cockroach protein and there is less cystine. The data vary significantly from data previously reported on the amino acid composition of the German cockroach (7). The earlier analysis, however, was conducted on insects with the entire head and digestive tract removed and the remaining portions of the body extracted with lipide solvents only. 

Olestra occurs as a solid, soft gel, or liquid at room temperature depending on the fatty acids used in manufacture. It is a mixture of the octa-, hepta-, and hexa-esters of sucrose prepared by the reaction of sucrose with edible C12 to C20 and higher fatty acid methyl esters. It is insoluble in water and soluble in common lipid solvents. 

Propofol can cause severe pain on injection, especially when injected into a small vein (20) the incidence is 25-74% (21). Administration of the lipid solvent in which propofol dissolved has confirmed that the solvent is responsible for this adverse effect (22). 

Properties Colorless needles odorless sour taste. Mp 236C, sublimes above melting point, d 1.473. Soluble in water and alcohol insoluble in most lipid solvents, quite stable to heat and oxidation. A vasodilator in high concentration. Amounts of niacin are expressed in milligrams. 

Properties Orange-yellow crystals bitter taste. Mp 282C (decomposes). Slightly soluble in water and alcohols insoluble in lipid solvents stable to heat in dry form and in acid solution. Stable to ordinary... 

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