Amino acids, preparation

If you synthesized the tnpeptide Leu Phe Ser from amino acids prepared by the Strecker synthesis how many stereoisomers would you expect to be formed ... 

A substrate is a substance that is the basic component of an organism. Protein substrates are amino acids, which are essential to life Protein substrates are amino acid preparations that act to promote the production of proteins (anabolism). Amino acids are necessary to promote synthesis of structural components, reduce the rate of protein breakdown (catabolism), promote wound healing, and act as buffers in the extracellular and intracellular fluids. Crystalline amino acid preparations are hypertonic solutions of balanced essential and nonessential amino acid concentrations that provide substrates for protein synthesis or act to conserve existing body protein. 

Cyclic peptide from 11 amino acids. Preparation by fermentation of Tolypocladium inflatum Gams with addition of DL-a-aminobutyric acid to the fermentation medium. Isolation by homogenization of mycelium, extraction with 90 % methanol and column chromatographic purification. 

The peptide/polypeptide product is usually hydrolysed by incubation with 6 mol l-1 HC1 at elevated temperatures (110 °C), under vacuum, for extended periods (12-24 h). The constituent amino acids are separated from each other by ion-exchange chromatography and identified by comparison with standard amino acid preparations. Reaction with ninhydrin allows subsequent quantification of each amino acid present. 

Lanikin, W. M., and C. W, Gehrke Quantitative gaschromatography of amino acids. Preparation of butyl N-trifluoracetyl esters. Analytic. Chem. 37, 383-389 (1965). 

Fig. 10. Different types of cyclopropyl-group containing amino acids prepared from chloro-cyclopropylideneacetates 1,2...

Treatment of PKU Most natural protein contains phenylalanine, and it is impossible to satisfy the body s protein requirement when ingesting a normal diet without exceeding the phenylalanine limit. Therefore, in PKU, blood phenylalanine is maintained in the normal range by feeding synthetic amino acid preparations low in phenylalanine, supplemented with some natural foods (such as... 

Table 2 A-Fmoc-A-methyl Amino Acids Prepared by the Solid-Phase Fukayama/Mitsunobu Reaction 92 ...

Table 5 A-Alkyl Amino Acids Prepared by the Reductive Alkylation of Zwitterionic Amino Acids1"01...

Scheme 18 Synthesis of Fmoc-Protected A" -(o>-BocHN-alkyl) Amino Acids Prepared by Nucleophilic Sub-...

The amino acids prepared by these methods are formed as racemic mixtures and are optically inactive. 

Exercises in thin-layer chromatography. Separation of amino acids. Prepare solutions of DL-alanine, L-leucine and L-lysine hydrochloride by dissolving 5 mg of each separately in 0.33 ml of distilled water, measured with a graduated 1 ml pipette (leucine may require warming to effect solution). Mix one drop of each solution to provide a mixture of the three amino acids and dilute the remainder of each solution to 1 ml to give solutions of the respective amino acids. The latter will contain about 5 pg of each amino acid per pi. Apply approximately 0.5 pi of each of the solutions to a Silica Gel G plate and allow to dry in the air (i.e. until the spots are no longer visible). 

When van Rij and co-workers (3) infused patients with various amino acid preparations, they found urinary zinc excretion to be higher with a sugar-containing preparation than when they used the same preparation without sugar. A unique zinc-binding substance was present in the sugar-containing solution and in the urine of patients infused with it. 

Vegad, H., Gray, C., Somers, P., and Dutta, A. (1997) Glycosylation of Fmoc amino acids preparation of mono- and di-glycosylated derivatives and their incorporation into Arg-Gly-Asp(RGD)-containing glycopeptides. J. Am. Chem. Soc. Perkin Trans I., 1429-1441. 

Enantiopure a-Amino Acids Prepared by Means of Diastereoselective Strecker... 

ENANTIOPURE a-AMINO ACIDS PREPARED BY MEANS OF DIASTEREOSELECTIVE STRECKER REACTIONS... 

Included in Scheme 2.32 are a series of bis(amino acids) prepared by Spantulescu et al. [63] by the decarboxylation of diacyl peroxides derived from combinations of protected aspartic and glutamic acids. In all cases, the reactions gave yields ranging from 52% to 66%. To prevent the formation of side products, the irradiation was performed on neat samples at low temperatures (—78 °C or — 96 °C). 

This section describes some derivatives of amino acids prepared by the condensation of a reagent with the amino group only or with both functional groups with the formation of a cyclic derivative. A number of reactions of this type have been tested for the derivatization of amino acids [191 ], mostly for a limited number. Some of the main reactions only will be mentioned here. 

The precursor to an amino acid prepared by enantioselective hydrogenation has a Z double bond conjugated with a carboxylic acid carbonyl group. 

Note. The name Vivactil is also applied to a vitamin/amino acid preparation. 

Food Industry—As far as the compounds participating in food production are concerned, some investigations into the synthesis of food flavors are reported. Key steps of the process are represented by the preparation of cycloketones bearing methyls as ring substituents, carried out by hydrogenolysis of precursor aminomethyl derivatives. The Mannich synthesis is also applied to amino acid preparations for animal nutrition. ... 

Amos. H. b., bvans, J. J., llimmelsbach. D. S., and Barton, F. li.. In vitro stability, in tivo hydrolysis, and absorption of lysine and methionine from polymerized amino acid preparations, J. Agric. Pood Chem.. 28, 1250. 1980 Chem. Abstr.. 93, 202990. 1980. 

Preparative Methods substituted 2,3-methanoamino acids are difficult to prepare. Unfortunately, most of the reported syntheses give racemic materials whereas stereochemically pure compounds are required for studies of cyclopropane-based peptidomimetics. The only 2,3-methanologs of protein amino acids prepared in optically active form are ( )- and (Z)-cyclo-Phe and -Tyr, all four stereoisomers of cyc/o-Met, (Z)-cyclo-Arg and (25,35)-(Z)-cyc/o-Trp, although several routes to enantio-enriched 2,3-methanologs of simple nonproteogenic amino acids have been reported. " The most practical synthesis of the title compound is that based on a diastereoselective, rhodium-catalyzed cyclopropanation reaction. ... 

After removal of the template, glycine was embedded in the cavity, depro-tonated, and alkylated. The highest enantiomeric excesses (36% ee) reported so far with imprinted polymeric reagents have been achieved with amino acids prepared in this way. This enantiomeric excess is purely a result of the asymmetric induction of the cavity. 

Step 7 (coupling) For rapid, accurate, and efficient operation, use one tared vessel (beaker) for weighing all Boc amino acids. Prepare a list of Boc amino acid derivatives with a column for their molecular weights and a column for the combined weight of the weighing vessel... 

Few experimental data are available for establishing the existence of Poisson distributions in poly a-amino acids prepared in this way. Fessler and Ogston [26] showed from sedimentation measurements that poly-sarcosine samples had sharp distributions which could be Poissonian, and Pope et al. [27], employing column fractionation, demonstrated a Poisson... 

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