Protein-bound Amadori compounds

Several methods have been developed for assaying non-enzymatic glycosylation. As far as biological systems are concerned, these have been extensively reviewed by A. J. Furth in 1988 (5). They include both assays on intact proteins after chemical degradation and selective detection of e.g. 5-hydroxymethylfurfural (HMF) and formaldehyde using the thiobarbituric assay (TEA), and assays on protein hydrolysates with or without previous reduction of the protein-bound Amadori compound. In this last case, the analysis is based on the determination of furosine which is specifically formed from lysine Amadori compounds with a yield of approximately 30% (6). The furosine method, originally developed for milk (7), has been the subject of several analytical improvements both for food products (8) and biological materials (9). More recently, another method has been proposed to evaluate the extent of early Maillard reaction in milk products. This method is based on direct measurement of the Amadori product lactuloselysine which is released after complete enzymatic hydrolysis (10). 

Periodate Oxidation of Protein-Bound Amadori Compounds Development of the CML Method... 

Early work by Hannan and Lea187 on pigment formation was concerned with glucose in relation to casein, poly-L-lysine, and V -acetyl-L-lysine. Similarity in behaviour fitted the expectation that the group primarily involved is the e-amino group of protein-bound lysine. Chemical tests suggest that colourless IV-glycosides are formed first, followed by Amadori compounds. 

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