Glucose with lysine

Figure 1. Comparison of the sensitivity of the various chemical procedures to lysine damage in a variety of heat-treated model soya protein samples. (All lysine data are given in g/16 g of N) Key - —, unheated —, heated alone — —, with glucose with xylose and--------------------------, with lactose.

Enzymes have been attached to a nylon matrix (135-13 7), a pig intestine (138), the hydrophobic membrane of a gas-selective sensor (139), and controlled pore glass (140). Recent comparative studies of the coupling agents GA and benzoquinone support the preferential use of benzoquinone for binding GOD to nylon mesh (13 7), or to cellulose acetate membranes (141) with lysine (13 7). Both investigations report robust electrode behaviors with respect to prolonged exposure to glucose, while lifetimes of the membrane electrodes were ca. 3 months. 

Fructosamine is the generic name for plasma protein ketoamines (for reviews, see Armbruster and Hill et aT ). The name refers to the structure of the ketoamine rearrangement product formed by the interaction of glucose with the -amino group on lysine residues of albumm. Analogous to GHb, measurement of fructosamine maybe used as an index of the average concentration of blood glucose over an extended period of time. 

During Strecker degradation of [l-i CJ-D-glucose with primary a-amino acids, pyrroles and pyridinols are formed as major products (6). 4-Aminobutyric acid and peptide bound lysine are transformed into [i3CHO]-2-formyl-5-hydroxymethylpyrroles (9). Amino acids like Val, He, Leu, Phe and Met are transformed into 2-[i3cjjO]-pyrrole lactones (70). Equimolar amounts of cysteine (methionine) and [l(or 6)- C]-D-glucose were heated for 1,5 h at 160°C in aqueous solution at pH 5. The volatiles were extracted with pentane/ether and analyzed as described (7). In Table I selected (unlabeled) Strecker degradation products from cysteine and methionine are summarized. Pyruvat (1), 2- and 3-mercaptopropionic acids (2, 3) from cysteine as well as 2-oxo-5-thiahexanoic acid (4) and 5-thiahexanoic acid (5) from methionine. 

Amadori reaction. - The 1-amino-1-deoxy-D-fructose derivative 5 was synthesized by condensation of D-glucose with hippuryl-lysine in methanol it was intended for use as a standard in the analysis of protein-fhictosamines by reaction with nitro blue tetrazolinium (NBT) undo alkaline conditions, but it and related peptide-fructosamines gave much lower relative responses than the protein-fructosamines in this assay. ... 

According to Tsuchida et al. [2], for a culture medium containing 13% glucose, 1% ammonium sulfate, and 1.2% fumaric acid (plus other trace nutrients etc.) the yield of L-phenylalanine was 21.7 mg/ml after 72 hr of cultivation at a temperature of 31.5°C. This represents a yield of approximately 16.7% from glucose by weight. Other amino acids are also produced in small quantities (<5 kg/m ), with Lysine making up approximately 50%. 

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