Amino acid using

Amberlite IRC-50 3.5 1.25 Methacrylic acid-DVB. Selectivity adsorbs organic gases such as antibiotics, alkaloids, peptides, and amino acids. Use pH >5. 

The sequence of each different peptide or protein is important for understanding the activity of peptides and proteins and for enabling their independent synthesis, since the natural ones may be difficult to obtain in small quantities. To obtain the sequence, the numbers of each type of amino acid are determined by breaking down the protein into its individual amino acids using concentrated acid (hydrolysis). For example, hydrolysis of the tetrapeptide shown in Figure 45.3 would give one unit of glycine, two units of alanine, and one unit of phenylalanine. Of course, information as to which amino acid was linked to which others is lost. 

More recent examples have employed a milder reagent system, triphenyl-phosphine and dibromotetrachloroethane to generate a bromo-oxazoline, which is subsequently dehydrohalogenated. Wipf and Lim utilized their method to transform intermediate 11 into the 2,4-disubstituted system of (+)-Hennoxazole k Subsequently, Morwick and coworkers reported a generalized approach to 2,4-disubstituted oxazoles from amino acids using a similar reagent combination, triphenylphosphine and hexachloroethane. ... 

Jackson and coworkers have used a new approach to the synthesis of fi-hydtoxy-ct-amino acids using farylthio nitrooxiranes. c-Jsopropylideneglyceraldehyde is converted into the corresponding 1-arylthio-l-nitroalkene, which is a key material for stereoselective synthesis of fi,Y-dihydroxyamino acids fScheme 4.6. The key step is stereoselective nucleophilic epoxlda-donof the Tarylthio-Tnltroalkene. Sy)i and ruin epoxides are selecdvely obtained by appropriate choice of epoxidadon reagent." ... 

Show how you could prepare the following amino acids using a reductive animation ... 

Human brain natriuretic peptide (BNP) is a small peptide of 32 amino acids used in the treatment of congestive heat failure. How many nitrogen bases are present in the DNA that codes for BNP ... 

The Japanese firm Tanabe Inc Ltd has been operating, since 1969, the optical resolution of DL-amino acids using aminoacylase. The prindple is based on the asymmetrical hydrolysis of N-acyl-DL-amino add by amino acylase which gives the L-amino add and the unhydrolysed acyl-D-amino add. 

Figure A8.6 Economic comparison of batch and continuous production of L-amino acids using amino acylases.

Figure A8.7 Preparation of optically pure a-methyl amino acids using carboxypeptidase A.

The original procedure for the trifluoroacetylation of amino acids used trifluoroacetic anhydride [Acetic acid, trifluoro-, anhydride].4 This reagent, although inexpensive and readily available, has certain disadvantages it is a highly reactive compound and thus has caused undesired reactions such as the cleavage of amide or peptide bonds,5 unsymmetrical anhydrides are formed between the newly formed A-trifluoroacetylamino acids and the by-product trifluoroacetic acid, and excess trifluoroacetic anhydride has caused racemization of asymmetric centers. 

In 1983, Yamada et al. developed an efficient method for the racemization of amino acids using a catalytic amount of an aliphatic or an aromatic aldehyde [50]. This method has been used in the D KR of amino acids. Figure 4.25 shows the mechanism of the racemization of a carboxylic acid derivative catalyzed by pyridoxal. Racemization takes place through the formation of Schiff-base intermediates. 

Figure 5.4 Deracemization of a-amino acids using D-amino acid oxidase in combination with sodium borohydride.

Table III. Detection Limits of 0PA/2-ME and NDA/CN Derivatized Amino Acids Using Conventional and Laser-Induced Fluorescence (LIF) Detection...

The first reported method for the direct phosphonomethylation of amino acids used phosphorous acid and formaldehyde (7). Typically, aqueous solutions of the amino acid, phosphorous acid, and concentrated (coned) hydrochloric acid were heated to reflux with excess aqueous formaldehyde or paraformaldehyde. The reaction proceeded equally well with either primary or secondary amines. However, with primary amines such as glycine, the yield of glyphosate was usually quite low, even at reduced temperature, and 1 1 1 stoichiometry. The resulting glyphosate acid (GLYH3) reacted faster than glycine, so the bis-phosphonomethyl adduct 2 always predominated. With excess phosphorous acid and formaldehyde, good isolated yields of this 2 1 adduct 2 have been obtained (8). 

Fig. 2.10 / -Amino acids used to investigate non-hydrogen-bonded structures...

J.L Matthews, C. Braun, C. Guibour-denche, M. Overhand, D. Seebach, Preparation of enantiopure y -amino acids from a-amino acids using the Arndt-Eis-tert homologation, in E. Juaristi (Ed.), Enantioselective Synthesis of f-Amino Acids, Wiley-VCH, New York, 1997. 

The repertoire of a-amino acids used by nature in the biosynthesis of proteins is limited to about 20 structures. Since the diversity of synthetically accessible a-amino acids is enormous, initial studies have been undertaken to investigate the possibilities offered by incorporation of noncoded amino acids into en2ymes. Some selected examples of successful modifications are presented below. 

The application of substrates isotopically labeled in specific positions makes it possible to follow the fate of individual atoms during the microbial degradation of xenobiotics. Under optimal conditions, both the kinetics of the degradation, and the formation of metabolites may be followed— ideally when samples of the labeled metabolites are available. Many of the classical studies on the microbial metabolism of carbohydrates, carboxylic acids, and amino acids used radioactive... 

OS 26] [R 4] [P 18] For dipeptide formation from the pentafluorophenyl ester of Boc-D-alanine and (S)-a-methylbenzylamine an extent of racemization of 5.6% was found [86]. This experiment also served to demonstrate monitoring of the racemization of an a-amino acid used in peptide synthesis. 

L-tryptophan is a naturally-produced, natural amino acid used as a dietary supplement. Samples from one manufacturer were found to be contaminated by trace amounts of another naturally occurring compound — l,l -ethylidene bis-[i.-tryptophan]. The latter compound appears to have been responsible for causing a number of deaths and additional cases of chronic eosinophilia-myalgia,111 some of which might have been prevented had there... 

Amino acids used include Gly, Ala, Phe, Leu, His, co-aminoheptanoic acid, and Ala-His dipeptide. It was found that not only single amino acids were added to the dextran, but also poly(amino acid) chains formed during the reaction. 

Sugars and Amino Acids, Using the AT-(2 4-dinitrophenyl) Derivatives. Science [Washington] 113, 354 (1951). 

Corr, L. T., Berstan, R. and Evershed, R. P. (2007a) Development of N acetyl methyl ester derivatives for the determination of 813C values of amino acids using gas chromatography combustion isotope ratio mass spectrometry. Analytical Chemistry 79, 9082 9090. 

Akagi T, Watanabe K, Kim H et al (2010) Stabilization of polyion complex nanoparticles composed of poly(amino acid) using hydrophobic interactions. Langmuir 26 2406—2413... 

Figure 11 Electropherogram of a mixture of five amino acids using indirect CL detection. Conditions 21-kV separation voltage, and 2 s at 21 kV for sample injection sample concentration 0.5 mM of each amino acid. Peak identities (1) arginine (2) leucine (3) serine (4) cysteine (5) aspartic acid. (From Ref. 86, with permission.)...

L-Cysteine is a high value a-amino acid used world-wide in a scale of 1200-15001 year-1 as additive in foodstuffs, cosmetics or as intermediate or active agent (as antidote to several snake venoms) in the pharmaceutical industry. Chemical routes generally lack the efficiency of electrochemical techniques, or they produce mixtures of l- and d- forms rather than the L-isomer. The most common electrochemical route is the cathodic reduction of L-Cystine in acid (usually HC1) solution to produce the stable hydrochloride. In Table 10, the charateristic data for a laboratory bench, laboratory pilot and a product pilot reaction using a DEM filter press are compared [13]. A production scale study was carried out in a filterpress reactor divided by a cation exchange membrane with a total area of 10.5 m2. The typical product inventory was 450 kg/24-hour batch time. For more details see Ref. [13]. 

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