fructosyl-glycine and fructosyl-lysine

Ribose-lysine (RL), ribose-glycine (RG), fructose-lysine (FL) and fructose-glycine (FG) Maillard models (whole mixture (WM) pH 4 and 9) were heated at 60, 80, 121°C for 30, 60, 120min, and dialysed into low (LMW) and high molecular weight (HMW) fractions. Reducing power (RP), DPPH and peroxyl radical scavenging (PRS) evaluated indirect antioxidant activity (AA). Direct AA in a water-in-oil emulsion was evaluated through peroxide value (PV), p-anisidine, TBARs inhibition and oxidative stability (OS). PRS and RP increased significantly with temperature and time from FLWM>HMW. With DPPH, only MRPs at 121°C exhibited higher AA than BHA. MRPs exhibited low PV, p-anisidine and inhibited the formation of TBARs. BHA showed the highest OS, with p-anisidine, PV and inhibition of TBARS similar to that of MRPs.

Topics: Antioxidants; Emulsions; Glycine; Hot Temperature; Lipid Peroxidation; Lipids; Lysine; Maillard Reaction; Oxidation-Reduction; Ribose

We have characterized the Bacillus subtilis homologs of fructoselysine 6-kinase and fructoselysine-6-phosphate deglycase, two enzymes that specifically metabolize the Amadori compound fructose-epsilon-lysine in Escherichia coli. The B. subtilis enzymes also catalyzed the phosphorylation of fructosamines to fructosamine 6-phosphates (YurL) and the conversion of the latter to glucose 6-phosphate and a free amino acid (YurP). However, their specificity was totally different from that of the E. coli enzymes, since they acted on fructoseglycine, fructosevaline (YurL) or their 6-phosphoderivatives (YurP) with more than 30-fold higher catalytic efficiencies than on fructose-alpha-lysine (6-phosphate). These enzymes are therefore involved in the metabolism of alpha-glycated amino acids.

Topics: Amino Acid Sequence; Amino Acids; Bacillus subtilis; Bacterial Proteins; Catalysis; Escherichia coli Proteins; Fructosamine; Fructose; Glycine; Glycoproteins; Kinetics; Lysine; Phosphorylation; Protein Binding

Topics: Amino Acids; Animals; Biological Transport; Caseins; Fructose; Glycine; Hot Temperature; Intestinal Absorption; Kidney; Liver; Lysine; Methionine; Muscles; Organ Specificity; Rats