Amino acid, analysis

the retention times of other sample components are not influenced by the NGl precolumn. 

The separation of amino acids on totally sidfonated cation exchangers is still one of the most commonly used methods for amino acid analysis. A milestone in the development of this method was the paper by Spackman, Stein, and Moore [29], published in 1958, which described an automated quantitative detection of physiological amino acids for the first time. This method, for which the authors received the Nobel Prize in 1972, utilized two ion-exchange columns acidic and 

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The amino add analysis of all peptide chains on the resins indicated a ratio of Pro Val 6.6 6.0 (calcd. 6 6). The peptides were then cleaved from the resin with 30% HBr in acetic acid and chromatogra phed on sephadex LH-20 in 0.001 M HCl. 335 mg dodecapeptide was isolated. Hydrolysis followed by quantitative amino acid analysis gave a ratio of Pro Val - 6.0 5.6 (calcd. 6 6). Cycll2ation in DMF with Woodward s reagent K (see scheme below) yielded after purification 138 mg of needles of the desired cyc-lododecapeptide with one equiv of acetic add. The compound yielded a yellow adduct with potassium picrate, and here an analytically more acceptable ratio Pro Val of 1.03 1.00 (calcd. 1 1) was found. The mass spectrum contained a molecular ion peak. No other spectral measurements (lack of ORD, NMR) have been reported. For a thirty-six step synthesis in which each step may cause side-reaaions the characterization of the final product should, of course, be more elaborate. 

Fig. 2. Amino acid analysis by automated ion-exchange chromatography. Standard column, 4.6 mm ID x 60 mm Ninhydrin developer. Computer print out indicates retention time (RT), height and area of peaks, and the ratio of the height of an amino acid in the sample to the height of a standard amino acid.

The most widely appHed colorimetric assay for amino acids rehes upon ninhydrin-mediated color formation (129). Fluorescamine [38183-12-9] and (9-phthalaldehyde [643-79-8] are popular as fluorescence reagents. The latter reagent, ia conjunction with 2-mercaptoethanol, is most often used ia post-column detection of amino acids separated by conventional automated amino acid analysis. More recently, determiaation by capillary 2one electrophoresis has been developed and it is possible to determine attomole quantities of amino acids (130). 

Amino acid analysis of a certain tetrapeptide gave alanine. 

How many peaks would you expect to see on the strip chart after amino acid analysis of bradykinin ... 

Automated amino acid analysis of peptides containing asparagine (Asn) and glutamine (Gin) residues gives a peak corresponding to ammonia. Why ... 

Mabbott, G., 1990. Qualitative amino acid analysis of small peptides by GC/ S. Journal of Chemical Education 67 441—445. 

Amino acid analysis itself does not directly give the number of residues of each amino acid in a polypeptide, but it does give amounts from which the percentages or ratios of the various amino acids can be obtained (Table 5.2). If the molecular weight and the exact amount of the protein analyzed are known (or the number of amino acid residues per molecule is known), the molar ratios of amino acids in the protein can be calculated. Amino acid analysis provides no information on the order or sequence of amino acid residues in the polypeptide chain. Because the polypeptide chain is unbranched, it has only two ends, an amino-terminal or N-terminal end and a carboxyl-terminal or C-termuial end. 

Amino acid analysis of an oligopeptide seven residues long gave... 

Amino acid analysis of another heptapeptide gave Asp Gin Leu Lys Met Tyr Trp NH4 ... 

Amino acid analysis of a decapeptide revealed the presence of the following products ... 

Analysis of the blood of a catatonic football fan revealed large concentrations of a psychotoxic octapeptide. Amino acid analysis of this octapeptide gave the following results ... 

Amino acid analysis of an octapeptide revealed the following composition ... 

A. Dossena, G. Galaverna, R. Coiradini and R. Marchelli, Two-dimensional liigh performance liquid chromatographic system foi the determination of enantiomeric excess in complex amino acid mixtures. Single amino acids analysis , ]. Chromatogr. 653 229-234 (1993). 

However, the use of a HPLC separation step enabled a remarkable acceleration of the deconvolution process. Instead of preparing all of the sublibraries, the c(Arg-Lys-O-Pro-O-P-Ala) library was fractionated on a semipreparative HPLC column and three fractions as shown in Fig. 3-2 were collected and subjected to amino acid analysis. According to the analysis, the least hydrophobic fraction, which eluted first, did not contain peptides that included valine, methionine, isoleucine, leucine, tyrosine, and phenylalanine residues and also did not exhibit any separation ability for the tested racemic amino acid derivatives (Table 3-1). 

William Howard Stein fl 911-1980) was born in New York City and received his Ph.D. in 1938 from the Columbia College of Physicians and Surgeons. He immediately joined the faculty of the Rockefeller Institute, where he remained until his death. In 1972, he shared the Nobel Prize in chemistry for his work with Stanford Moore on developing methods of amino acid analysis and for determining the structure of ribonuclease. 

Because the amount of time required for a given amino acid to elute from a standard column is reproducible, the identities of the amino acids in a peptide can be determined. The amount of each amino acid in the sample is determined by measuring the intensity of the purple color resulting from its reaction with ninhydrin. Figure 26.3 shows the results of amino acid analysis of a standard equimolar mixture of 17 a-amino acids. Typically, amino acid analysis requires about 100 picomoles (2-3 /xg) of sample for a protein containing about 200 residues. 

Figure 26.3 Amino acid analysis of an equimolar mixture of 17 amino acids. 

To determine the structure of a peptide or protein, the identity and amount of each amino acid present is first found by amino acid analysis. The peptide is... 

Amino Acid Analysis Visual Photometric b Value Method... 

In terms of amino acids bacterial protein is similar to fish protein. The yeast s protein is almost identical to soya protein fungal protein is lower than yeast protein. In addition, SCP is deficient in amino acids with a sulphur bridge, such as cystine, cysteine and methionine. SCP as a food may require supplements of cysteine and methionine whereas they have high levels of lysine vitamins and other amino acids. The vitamins of microorganisms are primarily of the B type. Vitamin B12 occurs mostly hi bacteria, whereas algae are usually rich in vitamin A. The most common vitamins in SCP are thiamine, riboflavin, niacin, pyridoxine, pantothenic acid, choline, folic acid, inositol, biotin, B12 and P-aminobenzoic acid. Table 14.4 shows the essential amino acid analysis of SCP compared with several sources of protein. 

Wilkins MR et al (1996) From proteins to proteomes large scale protein identification by two-dimensional electrophoresis and amino acid analysis. BioTechnol 14 61-65... 

HL-60 cellular proteins were labeled uniformly with [35S]methionine and then oxidized with H202. The proteins were then assayed for the presence of Met(O) using either the CNBr assay or amino acid analysis. 

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