Amino acids with fructose

The simplest member of the fructose-amino acid series is the glycine derivative, N-(l -carboxy)-methyl-l-amino-l-deoxy-D-fructose (7). Substances of this type are produced in the so-called chemical browning of foods and they have been isolated and characterized from hog liver. They may be obtained synthetically by heating the appropriate amino acid with a very large excess of D-glucose. Several workers have observed... 

Fukuoka was found to be homozygous for the 1615 G to A (539 Asp to Asn) mutation. This mutation occurred at relatively conserved amino acid residues and caused an alteration in hydrophobicity. Recently, we examined the structure-function relationship of these variants using the recombinant protein (F14). Although all of the four variants were found to be heat labile, the residual GPI activity seems to reflect clinical severity, such as the degree of anemia and episodes of hemolytic crisis. GPI Matsumoto, associated with severe anemia and hemolytic crisis, was extremely unstable, and GPI Iwate, which is associated with compensated hemolytic anemia, showed moderate heat instability. Affinity for substrate, fructose-6-phosphate, was slightly decreased in GPI Narita and GPI Fukuoka, which were associated with moderate anemia and hemolytic crisis. 

It is well known that the Maillard reaction in foods is initiated by the formation of colorless and tasteless intermediates, which preferentially are formed in low-moisture systems ( ,5.). In this way by reaction of glucose with amino acids fructose-amino acids are formed via Amadori rearrangement of the primary glucosyl-ami-no acids (1 ). Fructose-amino acids e.g. have been isolated from freeze-dried apricots and peaches ( 6,7,8j. Amadori compounds arising from aldoses and amino acids are formed during drying of foods of plant origin and can be easily detected by amino acid analysis (j>). 

In former experiments (5) we have shown that chemical analysis for Amadori compounds (mainly consisting of fructose-glutamic acid) and isovaleralde-hyde, formed by Strecker degradation of the amino acids leucine and isoleucine, can be used for an early detection of undesirable quality changes caused by the Maillard reaction. In order to demonstrate the usefulness of these compounds as indicator substances for quality improvement of dried products, we performed drying experiments with carrots as an example of plant products. 

Figure 6. Mutagenic activity of fructose-amino acid mixtures in Ames strain TA100. (Reproduced with permission from Ref. 58. Copyright 1981, Institute of...

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