Small Molecules specificity

Following the discovery of DQAsomes, we have explored these vesicles as the first available mitochondria-targeted colloidal drug and DNA delivery system. We were able to demonstrate in a series of papers that DQAsomes and DQAsome-like vesicles are well suited for the delivery of plasmid DNA and of small molecules specifically to mitochondria within living mammalian cells (38 3). 

His experimental investigations on immunity, begun in 1893, led to discovery of an accurate method for standardizing diphtheria anti-toxin. This prompted the State to create the Royal Institute for Experimental Therapy, for the statutory control of sera and vaccines. When Ehrlich assumed the Directorship in 1899, his reputation as a chemical pathologist had already been established internationally. He could well have rested on his laurels, but the chemist in him made him eager to launch out in an entirely new direction the cure of infectious diseases with small molecules, specific enough to be magic bullets that could harm only the invader. 

Some phosphatases are nonspecific, catalyzing the hydrolysis of a wide variety of substrates. Other phosphatases are small-molecule specific and hydrolyze a particular small-molecule phosphate ester or structurally similar substrates. Phosphoprotein-specific phosphatases accept particular phosphorylated proteins or peptides as substrates. The phosphoprotein-specific phosphatases can be subdivided into subgroups those specific for proteins phosphorylated on tyrosine those specific for proteins phosphorylated on serine or threonine and the so-called dual-specific enzymes, which accept both classes of phosphorylated proteins. More recently, a group of protein histidine phosphatases has been described. 

To be specific let us have in mind a picture of a porous catalyst pellet as an assembly of powder particles compacted into a rigid structure which is seamed by a system of pores, comprising the spaces between adjacent particles. Such a pore network would be expected to be thoroughly cross-linked on the scale of the powder particles. It is useful to have some quantitative idea of the sizes of various features of the catalyst structur< so let us take the powder particles to be of the order of 50p, in diameter. Then it is unlikely that the macropore effective diameters are much less than 10,000 X, while the mean free path at atmospheric pressure and ambient temperature, even for small molecules such as nitrogen, does not exceed... 

HyperChem uses two types of methods in calculations molecular mechanics and quantum mechanics. The quantum mechanics methods implemented in HyperChem include semi-empirical quantum mechanics method and ab initio quantum mechanics method. The molecular mechanics and semi-empirical quantum mechanics methods have several advantages over ab initio methods. Most importantly, these methods are fast. While this may not be important for small molecules, it is certainly important for biomolecules. Another advantage is that for specific and well-parameterized molecular systems, these methods can calculate values that are closer to experiment than lower level ab initio techniques. 

Biochemically, most quaternary ammonium compounds function as receptor-specific mediators. Because of their hydrophilic nature, small molecule quaternaries caimot penetrate the alkyl region of bdayer membranes and must activate receptors located at the cell surface. Quaternary ammonium compounds also function biochemically as messengers, which are generated at the inner surface of a plasma membrane or in a cytoplasm in response to a signal. They may also be transferred through the membrane by an active transport system. 

Haptens, a special class of antigen, are small molecules that induce specific antibody production when they are attached to a protein that acts as a carrier. Phosphorylcholine is one such hapten that has been widely used in the investigation of immune responses. The specific binding of this hapten... 

SERS has also been applied as a sensitive, molecule-specific detection method in chromatography, e.g. thin layer, liquid, and gas chromatography. SERS-active colloids were deposited on the thin layer plates or mixed continuously with the liquid mobile phases. After adsorption of the analytes, characteristic spectra of the fractions were obtained and enabled unambiguous identification of very small amounts of substance. 

Just as many small-molecule materials, polymers also form glasses [4]. Actually, most polymeric materials of everyday use are made of polymer glasses, polystyrene (PS) cups or compact discs made of polycarbonates, for instance. In many respects polymer glasses are very similar to small-molecule glasses, and there is nothing special about them. However, on the other hand, the special aspects of polymer materials allow specific studies beyond characteristic studies on small-molecule glasses. 

J., Palani, A., Shapiro, S., Clader, J. W., McCombie, S., Reyes, G. R., Baroudy, B. M., and Moore, J. P. (2002). HIV-1 escape from a small molecule, CCR5-specific entry inhibitor does not involve CXCR4 use. Proc. Natl. Acad. Sci. USA 99 395-100. 

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