Peptides steroidal

Membranes offer a format for interaction of an analyte with a stationary phase alternative to the familiar column. For certain kinds of separations, particularly preparative separations involving strong adsorption, the membrane format is extremely useful. A 5 x 4 mm hollow-fiber membrane layered with the protein bovine serum albumin was used for the chiral separation of the amino acid tryptophan, with a separation factor of up to 6.6.62 Diethey-laminoethyl-derivatized membrane disks were used for high-speed ion exchange separations of oligonucleotides.63 Sulfonated membranes were used for peptide separations, and reversed-phase separations of peptides, steroids, and aromatic hydrocarbons were accomplished on C18-derivatized membranes. 

This seventh edition includes discussions of neurotransmitters ranging from acetylcholine through other amines, amino acids, purines, peptides, steroids and lipids Whereas in most cases their metabolism and receptor interactions are known, much current research involves questions of identification of effector pathways, their regulation and control. 

Oligonucleotides, Peptides, Steroids Analytical separations Ion Exchange, Reversed Phase disks [79]... 

Certain proteins, peptides, steroids, and other small organic molecules, serve as cell messengers or mediators of signals. Hydrophilic mediators activate receptors at the surface of the target cell. Acetylcholine is a common example of such signaling molecules. It becomes bound on the exterior surface at the acetylcholine receptor of the nervous system, opening the channel. 

Radioimmunoassay (RIA), whether it is used for the measurement of peptides, steroids or drugs, has many attractions, particularly for the routine laboratory engaged in the analysis of large numbers of samples. 

Hormones can be glycoproteins, polypeptides, peptides, steroids, or modified amino acids. They function as messengers traveling through the bloodstream to target tissues and organs, where they bind to surface... 

Most of the 49 transporters recognize and transport a variety of xenobiotics as well as physiological substrates that include bile acids, peptides, steroid ions, and phospholipids. However, of these 49 transporters MRPl, Pgp and BGRP are the best documented for their role in conferring anticancer drug resistance and for this reason will be the focus of our discussion in this portion of the chapter. 

Kingan, T. (1989). A Competitive Enzyme-linked Immunosorbent Assay Applications in the Assay of Peptides, Steroids, and Cyclic Nucleotides, Biochem. 183 283-289. 

Biomedical Organic acids, lipids Carbohydrates Porphyrins and bile pigments Amino acids, peptides Steroids, doping... 

The Rollgen s group [9] reports the thermal desorption of [M + Alkah]" quasi-molecular ions from a electrically heated metal smface (wires or ribbons) for so-dimn alkah salts of carboxylic acids and mixtures of alkali halides with a crown ether, glucose and adenosine. With benzo-15-crown-5 the desorption of [M + Na]" ions takes place even below the threshold temperature for thermionic emission of alkah ions. Alkali ion attachment has also been performed by thermal desorption of thermally labile analytes such as saccharides, pharmaceuticals, peptides, steroids and their mixtirres. Bombick and Alhson [8] describe a desorption/ioniza-tion method where samples are deposited directly on thermionic emission materials (lK20 lAl203 2Si02) and heated within the mass spectrometer s source. Ions representative of the sample are formed. The proposed mechanism involves the gas-phase addition of emitted potassium ions to neutrals desorbed from the surface. 

An early account on lAMS for compounds with biological relevance is the thermal desorption ion source described by Rollgen [11]. Electrically heated metal sttrfaces doped with alkali-cation salts and compounds such as crown ether, sugars, drags, peptides, steroids, and nucleosides were used to generate [M+Na]" at sttrface temperatures way below the threshold temperatures for thermionic emission. 

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