由木糖和15N标记的甘氨酸形成的美拉德氏聚合物的氮素形态

Water-soluble,nondialyzable Maillard polymers were prepared by reacting D-xylose with ^15N-glycine (and /or glycine)at 6８℃ and pH 8.0 at equimolar concentrations of 1,0.5 and 0.1 mol L^-1,respectively, for 13 days and partitioned into acid-insoluble(MHA) and acid-soluble(MFA) fractions.The nitrogen froms in these polymers were studied by using the ^15N cross polartisation-magic angle spinning nuclear magnetic resonance(CPMAS NMR) technique in combination with chemical methods .The ^15N nuclear magnetic resonance(NMR) data showed that while the yield,especially the MHA /MFA ratio,varied considerably with the concentrations of the reactants,the nitrogen distribution patterns of these polymers were quite similar. From 65% to 70% of nitrogen in them was in the secondary amide and /or indole form with 24%-25% present as aliphatic and /or aromatic amines and 5% to 11% as pyrrole and /or pyrrole-like nitrogen,More than half (50%-77%) of the N in these polymers were nonhydrolyzable,The role of Maillard reacion in the formation of nonhydrolyzable nitrogen in soil organic matter is discussed.

Nitrogen Forms of Maillard polymers derived from xylose and 15N-labelled glycine