Carbohydrate and amino acid degradation pathways in L-methionine/D-[13C] glucose model systems.
Maillard model systems consisting of labeled D-[(13)C]glucoses, L-[(15)N]methionine, and L-[methyl-(13)C]methionine, have been utilized to identify the amino acid and carbohydrate fragmentation pathways occurring in the model system through Py-GC/MS analysis. The label incorporation analyses have indicated that the carbohydrate moiety produces 1-deoxy- and 3-deoxyglucosones and undergoes C(2)/C(4) and C(3)/C(3) cleavages to produce glycolaldehyde, tetrose, and C(3)-reactive sugar derivatives such as acetol, glyceraldehyde, and pyruvaldehyde. Glycolaldehyde was found to incorporate C-1, C-2 (70%) and C-5, C-6 (30%) glucose carbon fragments, whereas the tetrose moiety incorporates only C-3, C-4, C-5, C-6 glucose carbon atoms. In addition, the major source of reactive C(3) fragments was found to contain C-4, C-5, C-6 sugar moiety. On the other hand, methionine alone also generated Strecker aldehyde as detected by its condensation product with 3-(methylthio)propylamine. Plausible mechanisms were proposed for the formation of the interaction products between sugar and amino acid degradation products on the basis of the label incorporation patterns.
McGill University, Department of Food Science and Agricultural Chemistry, 21111 Lakeshore, Ste. Anne de Bellevue, Quebec, Canada, H9X 3V9. yaylayan@macdonald.McGill.CA
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Keyhani
D000596:Amino Acids / Q000737:chemistry*; D002241:Carbohydrates / Q000737:chemistry*; D002247:Carbon Isotopes; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D005947:Glucose / Q000737:chemistry*; D008715:Methionine / Q000737:chemistry*; D008956:Models, Chemical; D009587:Nitrogen Isotopes
D000596:Amino Acids; D002241:Carbohydrates; D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D008715:Methionine; D005947:Glucose