Role of oxygen radical reactions in the browning and cross-linking of lysozyme by glucose
Lysozyme (LZM) was used as a model protein for studies on the effects of oxygen on the Maillard reaction. During a 4 wk incubation in 0.25 M glucose (0.2 M phosphate buffer, pH 7.4, 37/sup 0/C) the kinetics of glycation of LZM were similar under air and N/sub 2/, yielding approx.2 mol Lys modified per mol LZM. Fructoselysine (FL) was the major Lys derivative formed under air and N/sub 2/, while N/sup epsilon/-carboxymethyllysine (CML) accounted for approx.30% of FL formed at 4 wk under air. A loss of 1 mol Arg per mol LZM was also observed under both air and N/sub 2/, with greater loss from LZM dimer vs. monomer, suggesting a role for Arg in the crosslinking reaction. Dimer and monomer did not differ in content of Lys, FL or CML (under air), but dimer was 4 times as fluorescent as monomer, suggesting that crosslink structures are fluorescent. Despite significant differences in kinetics of crosslinking, browning and development of fluorescence of LZM under air vs. N/sub 2/, products formed had similar absorbance and fluorescence spectra. Based on inhibition by chelators and radical scavengers, the more rapid crosslinking and development of fluorescence under air was shown to result from oxygen radical reactions. These results indicate that both radical and non-radical processes may contribute to the Maillard reaction, but that the browning, fluorescence and crosslinking of protein may proceed in the absence of oxygen and oxygen radicals.
- Research Organization:
- Univ. of South Carolina, Columbia
- OSTI ID:
- 6956346
- Report Number(s):
- CONF-8606151-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:6; Conference: 76. annual meeting of the Federation of American Society for Experimental Biology, Washington, DC, USA, 8 Jun 1986
- Country of Publication:
- United States
- Language:
- English
Similar Records
Proton-bound dimers of nitrogen heterocyclic molecules: Substituent effects on the structures and binding energies of homodimers of diazine, triazine, and fluoropyridine
Kinetics of PBX9404 Aging
Related Subjects
GLUCOSE
BIOLOGICAL EFFECTS
LYSOZYME
CROSS-LINKING
OXYGEN
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MODELS
FLUORESCENCE
RADICALS
ALDEHYDES
CARBOHYDRATES
CHEMICAL REACTIONS
ELEMENTS
ENZYMES
GLYCOSYL HYDROLASES
HEXOSES
HYDROLASES
KINETICS
LUMINESCENCE
MONOSACCHARIDES
NONMETALS
O-GLYCOSYL HYDROLASES
ORGANIC COMPOUNDS
POLYMERIZATION
REACTION KINETICS
SACCHARIDES
560300* - Chemicals Metabolism & Toxicology