Basicity of amino acids

Measuring Gas-Phase Basicities of Amino Acids Using an Ion Trap Mass Spectrometer 78... 

When this sudoku puzzle is assigned, some training of students is recommended. One possibility is, at the onset of the discussion of amino acids, to hand out the puzzle and to use it as one of the visual aids to point out the basics of amino acids. The instructor can show the correlation of the name, structure, and abbreviations and then follow up with a demonstration of the method and thought process used to solve the puzzle. For instance, as a class, one may complete all instances of lysine in the puzzle. Students who are unfamiliar with this type of puzzle would learn the strategy necessary. All students would better comprehend the necessity of identifying which structures, names, and abbreviations are correlated with each other. 

Ryzhov V, Sunderlin SS, Keller LMM, Gaillard ER. Measuring gas-phase basicities of amino acids using an ion trap mass spectrometer. A physical chemistry laboratory experiment. J Chem Educ. 2005 82 1071-3. 

It should be noted that Werner s reaction mechanism is analogous to that by which formaldehyde destroys the basicity of amino acids in the Sorenson procedure for titrating these acids (page 220). 

The history of the discovery of amino acids is closely related to advances ia analytical methods. Initially, quantitative and qualitative analysis depended exclusively upon crystallization from proteia hydrolysates. The quantitative precipitation of several basic amino acids including phosphotungstates, the separation of amino acid esters by vacuum distillation, and precipitation by sulfonic acid derivatives were developed successively duriag the last century. 

Ben2enesulfonate compounds yield very iasoluble salts which have been used for separation and identification of amino acids (89). Similarly, phosphotungstic acid forms iasoluble salts with basic amino acids such as lysiae, arginine, and cysteiae. 

In Parenteral and Enteral Nutrition. Amino acid transfusion has been widely used since early times to maintain basic nitrogen metaboHsm when proteinaceous food caimot be eaten. It was very difficult to prepare a pyrogen-free transfusion from protein hydrolysates. Since the advances in L-amino acid production, the crystalline L-amino acids have been used and the problem of pyrogen in transfusion has been solved. The formulation of amino acid transfusion has been extensively investigated, and a solution or mixture in which the ratio between essential and nonessential amino acid is 1 1, has been widespread clinically. Special amino acid mixtures (eg, branched chain amino acids-enriched solution) have been developed for the treatment of several diseases (93). 

Enzymes are basically specialty proteins (qv) and consist of amino acids, the exact sequence of which determines the enzyme stmcture and function. Although enzyme molecules are typically very large, most of the chemistry involving the enzyme takes place in a relatively small region known as the active site. In an enzyme-catalyzed reaction, binding occurs at the active site to one of the molecules involved. This molecule is called the substrate. Enzymes are... 

The basic structural unit of these two-sheet p helix structures contains 18 amino acids, three in each p strand and six in each loop. A specific amino acid sequence pattern identifies this unit namely a double repeat of a nine-residue consensus sequence Gly-Gly-X-Gly-X-Asp-X-U-X where X is any amino acid and U is large, hydrophobic and frequently leucine. The first six residues form the loop and the last three form a p strand with the side chain of U involved in the hydrophobic packing of the two p sheets. The loops are stabilized by calcium ions which bind to the Asp residue (Figure S.28). This sequence pattern can be used to search for possible two-sheet p structures in databases of amino acid sequences of proteins of unknown structure. 

Gene The basic unit of inheritance a sequence of DNA coding that can be translated by the cell machinery into a sequence of amino acids linked to form a protein. 

For the separation of amino acids, the applicability of this principle has been explored. For the separation of racemic phenylalanine, an amphiphilic amino acid derivative, 1-5-cholesteryl glutamate (14) has been used as a chiral co-surfactant in micelles of the nonionic surfactant Serdox NNP 10. Copper(II) ions are added for the formation of ternary complexes between phenylalanine and the amino acid cosurfactant. The basis for the separation is the difference in stability between the ternary complexes formed with d- or 1-phenylalanine, respectively. The basic principle of this process is shown in Fig. 5-17 [72]. 

Fig. 12a and b. Transport of amino acids through a toluene barrier a from basic to acid aqueous phases using a positively charged carrier (N +, tricaprylylmethylammonium chloride, Aliquat 336) b from acid to basic aqueous phases using a negatively charged carrier (DNNS ", dinonylnaphthalene-sulfonate). (Cited from Ref.70))... 

Hayama et al.132 discussed the catalytic effects of silver ion-polyacrylic add systems toward the hydrolyses of 2,4-dinitrophenylvinylacetate 84 (DNPVA) by using the weak nudeophilicity of carboxylic groups and the change-transfer interactions between olefinie esters and silver ions133Metal complexes of basic polyelectrolytes are also stimulating as esterase models. Hatano etal. 34, 13S) reported that some copper(II)-poly-L-lysine complexes were active for the hydrolyses of amino acid esters, such as D- and L-phenylalanine methyl ester 85 (PAM). They... 

N-Bromoamino acids form within seconds after mixing aqueous bromine and the amino acid in dilute aqueous solution (ref. 6), but are not stable end products of the reaction. Thus, Friedman and Morgulis (ref. 7) found that the oxidation of amino acids by hypobromite gives aldehydes and nitriles with one carbon atom less than the original amino acid, ammonia and CO2 (Scheme 1). The proportions of aldehyde and nitrile depend on the basicity of the medium, aldehyde formation being favoured by more basic conditions. 

The R groups of amino acids determine their unique biochemical functions. Amino acids are classified as basic, acidic, aromatic, aliphatic, or sulfur-containing based on the properties of their R groups. 

The lateral diverticulum cells in semi-terrestrial species such as toads can still detect a wide range of amino acids, comparable to the properties of fish neuroepithelium. Both water-soluble and volatile odourants are discriminated by the olfactory neurones of the Clawed toad (Xenopus) (Iida and Kashiwayanagi, 1999). When single olfactory neurones were tested with acidic, neutral and basic amino acids, over 50% of the receptors gave some excitatory response. 

D Burston, DM Matthews. (1972). Intestinal transport of dipeptides containing acidic and basic L-amino acids and a neutral D-amino acid. Clin Sci Mol Med 42 4P. 

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