Lysine reaction system

Loss of Available Lysine in Protein in a Model Maillard Reaction System... 

Imine formation, the Amadori rearrangement, and aminoketose decomposition, with glucose or xylose and tryptophan, led to activation volumes of 14, + 8, and +17 ml, mol pressure thus accelerating the first, but retarding the other two reactions.106 As a consequence, the formation of certain volatiles, such as norfuraneol at pH 7 and 2-methylpyrazine at pH 10 in lysine-xylose systems, is greatly decreased.107... 

E.-H. Ajandouz, L. S. Tchiakpe, F. Dalle Ore, A. Benajiba, and A. Puigserver, Effects of pH on caramelization and Maillard reaction kinetics in fructose-lysine model systems, J. Food Sci., 2001, 66, 926-931. 

Cuzzoni, M.T. Stoppini, G. Gazzani, G. Influence of water activity and reaction temperature of ribose-lysine and glucose-lysine Maillard systems on mutagenicity, absorbancy, and content of furfurals. Food Chem. Toxicol. 1988, 26,815-822. 

Interestingly, the nucleophilic addition of water in the sequence of events giving rise to 41 represents a relevant model system for investigating the mechanism of the generation of DNA-protein cross-links under radical-mediated oxidative conditions [80, 81]. Thus, it was shown that lysine tethered to dGuo via the 5 -hydroxyl group is able to participate in an intramolecular cyclization reaction with the purine base at C-8, subsequent to one electron oxidation [81]. 

These initial findings do not exclude other possible formaldehyde-induced reactions with tissue proteins. Notably, this first model system was not designed to detect the role of lysine residues. Lysine has a propensity to react with and form a variety of different types of cross-links with other amino acids in the presence of formaldehyde.1,3 417 Therefore, it is likely to also be important in reactions with formaldehyde. In fact, peptides with internal lysine residues were purposefully excluded from this initial study for technical reasons. To explore the importance of lysine residues in antigen retrieval, an alternative method was employed. 

A spectrophotometric method for determination of primary and secondary amines requires development for each particular compound, determining the kinetics of reaction of the amine with sodium l,2-naphthoquinone-4-sulfonate (143) and the UVV absorption spectrum of the product, under a set of fixed conditions. The procedure was applied to determination of ephedrine (30) and amphetamine (28) in pharmaceutical samples339. Reagent 143 in a FLA. system was used for the fast determination of lysine (144) in commercial feed samples by multivariate calibration techniques, without need of chromatographic separation340. 

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