Lipid biological properties

The protein Ras, an important intracellular signal transducer, is crucially involved in the development of tumor growth. The farnesylation of Ras, catalyzed by the enzyme Ras-farnesyl-transferase, is essential to its proper functioning in the normal and in the transformed state. Therefore, the inhibition of Ras lipidation has become a promising target for the development of new classes of anti-tumor agents. This review focuses on the different classes of Ras-farnesyl-transferase inhibitors and compares their biological properties and modes of action in vitro as well as in vivo. 

Lipid A constitutes the covalently bound lipid component and the least variable component of LPS (25). It anchors LPS to the bacterial cell by hydrophobic and electrostatic forces and mediates or contributes to many of the functions and activities that LPS exerts in prokaryotic and eukaryotic organisms. In the following sections, the primary structure of lipid A of different Gram-negative bacteria is described, together with some of its characteristic biological properties. Furthermore, this article describes some of the principal methods that have been used for the structural analysis of lipid A and discusses their merits and limitations. 

Much more exciting biologic properties have been revealed for the equally 1,6-disubstituted phenazoviridin (56) isolated from Streptomyces sp. HR04. The new free radical scavenger showed strong in vitro inhibitory activity against lipid peroxidation and displayed in vivo antihypoxic activity in mice [57]. 

Considering that LEH is still in a developmental phase, it is imperative that each batch of LEH is fully characterized for physicochemical and biological properties. Typically, lipid content, particle diameter, oxygen affinity, hemoglobin, methemoglobin, carbonyl-hemoglobin, oncotic pressure, viscosity, endotoxin, and osmolality are determined by conventional methods. Several issues that need specific attention in the case of LEH are as follows ... 

Frederiksen H.K., Kristensen H.G., and Pedersen M., Solid lipid microparticle formulations of the pyrethroid gamma-cyhalothrin-incompatibility of the lipid and the pyrethroid and biological properties of the formulations, J. Control. Rel, 86, 243, 2003. 

Comparson of the transitions observed by differential scanning calorimetry in membranes of M. laidlawii and in water dispersions of the lipids from the membranes support the concept that most of the lipids exist as a smectic mesophase in the membranes. The evidence for a bilayer structure is straightforward in this case. Lipid transition temperatures are a function of fatty acid composition and correlate well with biological properties. The calorimeter possesses advantages over high resolution NMR for M. laidlawii, and perhaps in many other systems, because the data can be interpreted less ambiguously. In M. laidlawii membranes the bilayer appears to be compatible with the same physical properties observed in other membranes—a red-shifted ORD, lack of ft structure in the infrared, reversible dissociation by detergents, and poorly... 

Many methods exist to separate triglycerides into fractions on the basis of their degree of unsaturation. These include fractional crystallization from solvents, and separation by column and thin layer chromatography (TLC). The classes of triglycerides may then be studied and after methylation the fatty acid content determined by GLC. Yet even this is not the whole story since the position of fatty acids on the triglyceride molecule may uniquely affect the physical and biological properties of the lipid. 

Hofmann, A.F., and A. Roda. 1984. Physicochemical properties of bile acids and their relationship to biological properties An overview of the problem. J Lipid Res 25 1477. 

These reactive metabolites can bind covalently to cellular macromolecules such as nucleic acids, proteins, cofactors, lipids, and polysaccharides, thereby changing their biologic properties. The liver is particularly vulnerable to toxicity produced by reactive metabolites because it is the major site of xenobiotic metabolism. Most activation reactions are catalyzed by the cytochrome P450 enzymes, and agents that induce these enzymes, such as phenobarbital and 3-methylcholanthrene, often increase toxicity. Conversely, inhibitors of cytochrome P450, such as SKF-525A and piperonyl butoxide, frequently decrease toxicity. 

Although H. pylori induces chronic infection whereas C. jejuni induces an acute infection (and to which the structural characteristics and biological properties of endotoxin, particularly their lipid A components contribute), both bacteria induce pathogenic autoimmune responses in which molecular mimicry in the... 

Biotechnological transformation is powerful tool to effectively utilize a broad variety of plant oils, with the aim to modify their structure for the production of new lipid-based materials with demanded properties and functions. One method of plant oil transformation is based on the direct utilization by microorganisms. Employed oils can be converted to aimed compounds by submerged cultivation or oils, and/or oleaginous plant materials can be utilized during solid state fermentation to useful bioproducts enriched with demanded microbial products. Another biotransformation technique covers the enzymatic modification of oil components to structured lipids with biological properties. 

The biological properties associated with the polysaccharides are those relating to serological specificity, and, at least to some extent, they serve as bacteriophage receptors. The somatic antigens are also referred to as Endotoxins, but their toxic properties and manifold physiological effects are due to the lipide component, and this subject has been adequately reviewed. ... 

Mass Spectrometry Overview of Applications in Chemical Biology Lipid Bilayers, Properties of... 

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