Simple amino acids action

The study of fish proteins were initiated by the Swiss physiologist Miescher (1897), who first isolated the protamines from the sperm cells of various fishes as early as 1868. The relatively simple amino acid composition of these proteins and their pharmacological action have since promoted extensive researches, first of aU by Kossel and co-workers, whose important... 

To imderstand the actions of domoic acid in the nervous system, we must recognize its structural similarities with glutamic acid (see Figure 1). While most people not familiar with nervous system function think of glutamate as a simple amino acid that participates in biochemical pathways (e.g. feeding carbon atoms into the... 

We shall see in a subsequent chapter what is to be thought of the presence here of the albumoses and the peptones. Let us pause for the moment in consideration of the end products, which form the greater part of tryptic hydrolysis. And first of all, it should be noted that these crystalline compounds, non-biuretic and not precipitable by phosphotungstic add, have absolutely nothing in common with those of the corresponding fraction obtained in peptic action whereas the former are very simple amino-acids, the latter are compoimds, capable even of being transformed by degradation into peptones. 

The use of IR action spectroscopy in the stmctural characterization of gas-phase (bio-)molecular ions has become well established within the fields of ion chemistry and mass spectrometry. It has been the subject of various recent reviews [ 142,164, 172, 180-184] and has been applied to extract stmctural information from ions ranging in size from simple amino acids to entire proteins [185-187]. Applications to diverse classes of biomolecular ions are described in various chapters of this book. 

Thiostrepton family members are biosynthesized by extensive modification of simple peptides. Thus, from amino acid iacorporation studies, the somewhat smaller (mol wt 1200) nosiheptide, which contains five thiazole rings, a trisubstituted iadole, and a trisubstituted pyridine, is speculated to arise from a simple dodecapeptide. This work shows that the thiazole moieties arise from the condensation of serine with cysteiae (159,160). Only a few reports on the biosynthesis of the thiostrepton family are available (159,160). Thiostrepton is presently used ia the United States only as a poly antimicrobial vetetinary ointment (Panalog, Squibb), but thiazole antibiotics have, ia the past, been used as feed additives ia various parts of the world. General (158) and mechanism of action (152) reviews on thiostrepton are available. 

Pharmacological Action. Certain of the simple amines and amino-acids found in ergot are pharmacologically active and have some influence on... 

These peptides were characterized in vitro and found to be powerful opioid agonists in the mouse vas deferens (MVD) and guinea pig ileum (GPI) assay. In vivo (rat tail-flick) they are only active when administered directly to the brain - a general limitation of simple linear peptides consisting of natural L-amino acids - but with less potency and shorter duration of action than morphine (Casy and Parfitt, 1986). 

There are simple reagents that react selectively with the carboxyl terminus of a peptide, but they have not proved as generally useful for analysis of the C-terminal amino acids as has the enzyme carboxypeptidase A. This enzyme catalyzes the hydrolysis of the peptide bond connecting the amino acid with the terminal carboxyl groups to the rest of the peptide. Thus the amino acids at the carboxyl end will be removed one by one through the action of the enzyme. Provided that appropriate corrections are made for different rates of hydrolysis of peptide bonds for different amino acids at the carboxyl end of the peptide, the sequence of up to five or six amino acids in the peptide can be deduced from the order of their release by carboxypeptidase. Thus a sequence such as peptide-Ser-Leu-Tyr could be established by observing that carboxypeptidase releases amino acids from the peptide in the order Tyr, Leu, Ser ... 

TMS derivatives of amino acids were also combined with other procedures and some difficulties were thus avoided. N-TMS-methyl and -ethyl esters of most protein amino acids were prepared by the action of TMSDEA on alkyl esters of amino acids and were chromatographed on methylsilicone stationary phases [246], Their retention times were found to be 15—20% lower than those of the corresponding TMS derivatives. Despite having an additional step in comparison with direct silylation, the procedure was applied by Hardy and Kerrin [259] to the GC analysis of twenty protein amino acids, including Hypro and CysH. Amino acids were esterified with a 3 N HC1 solution in n-butanol at 150°C for 15 min with subsequent silylation with BSTFA for 90 min at the same temperature. Acetonitrile and methylene chloride were used as solvents for the silylation. In the former solvent double derivatives of Gly and Lys (bis- and tris-) were produced, whereas in the latter the less silylated form only was produced. As Arg, in contrast to direct silylation, also leads to one peak in this instance, methylene chloride is recommended as the silylation solvent. The separation of all twenty amino acids was achieved on a simple column with 2% of OV-7 on GLC-110 textured glass beads (100—120 mesh). 

Hormonal amines are derived from amino acids and, in most cases, represent simple modifications of the parent compound. Table 30-1 lists the important hormonal amines, parent amino acids, major sites of synthesis, and principal actions. All of these amines except the thyroid hormones (Chapter 33) are decarboxylated products that are synthesized both in and out of the nervous system. Within the nervous system, they are important neurotransmitters outside the nervous system, the cells that produce... 

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