E Amino Acids

Detection powders and fingerprint development kits commonly contain cream- or yellow-colored ninhydrin crystals or a solution of dissolved ninhydrin. Ninhydrin (also known as 1,2,3-indantrione, monohydrate 2,2-dihydroxy-1,3-indandione triketohydrindene, monohydrate and triketohydrinden hydrate) has the structure presented in Fig. 13.3.1. Ninhydrin will react with a free a-amino group, -NH2. This group is contained in all amino acids, and analysis with ninhydrin is often performed to verify the presence of amino acids. When a-amino acids (i.e., amino acids with the structure NH2-CHR-COOH) react with ninhydrin, a characteris-... 

Hare, P. E., Amino acid dating, limitations, and potential, Geoloqical Soc. America, Abstracts with Programs, 9, 1004-1005 (1977). 

Hassan, A. A., Hare, P. E., Amino Acid Analysis in Radiocarbon Dating of Bone Collagen, In Archaeological Chemistry II, p. 109-116, Washington, D.C., American Chemical Society, 1978. 

Aspartame, N-a-L-aspartyl-L-phenylalanine methyl ester, trade names NutraSweet , and Aspartil , is a dipeptide derivative. Like dipeptides aspartame is metabolised into the constituents, i.e. amino acids and methanol. Therefore studies into the metabolic behaviour and the fate of metabolites were carried out. Levels of blood aspartate and glutamate were measured after intake of high aspartame doses. Changes were transient and allegations of influences of high aspartame levels on brain function could never be verified. 

Amines other than a-amino acids will also give a colour reaction with ninhydrin but without the production of carbon dioxide. Thus /3-, y-, 8- and e-amino acids and peptides react more slowly than a-amino acids, to give the blue complex, while imino acids result in the formation of a yellow-coloured product which can be measured at 440 nm. Removal of substances such as protein, ammonia and urea from biological samples may be necessary in quantitative work because they also react in a similar manner. 

Protein drugs also represent a special case. Unlike small molecules, two protein drugs with the same chemical formula (i.e. amino acid sequence) might have subtle changes in folding... 

PTH is a single-chain polypeptide composed of 84 amino acid residues that is devoid of disulfide bonds and has a molecular weight of 9500. Biological activity of the human hormone resides primarily in the amino terminal end of the protein (i.e., amino acids 1-34). This portion of PTH has full biological activity both in vivo and in vitro. Synthetic fragments of the 1-34 portion of the PTH molecule have been synthesized. A paraneoplastic hormone, PTH related peptide (PTHrP) has been identified, isolated, and synthesized. PTHrP is... 

In more acidic solutions, monodentate O-bonded complexes are formed.1177,1175 1178 Ring closure is rapid if the pH is raised y, 6 and e amino acid complexes do not undergo ring closure.1179... 

FIGURE 2-20 Th e amino acid histidine, a component of proteins, is a weak acid. The pKa of the protonated nitrogen of the side chain is 6.0. 

E. Amino acids that form succinyl CoA Methionine... 

King, K., and Hare, P. E. Amino acid composition of planktonic foraminifera A paleobio-chemical approach to evolution. Science 175, 1461—1463 (1972). 

K2. Kirk, E., Amino acid and ammonia metabolism in liver disease. Acta Med. Scand. Suppl. 78 (1936). 

Reaction E Amino acid degradation (Strecker degradation)... 

Cieslik, E., Amino acid content of Jerusalem artichoke (Helianthus tuberosus L.) tubers before and after storage, in Proceedings of the 7th Seminar on Inulin, Leuven, Belgium, 1998a, pp. 86-87. 

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