Amino-carbonyl Reaction of Oligosaccharides or Nucleic Acid, and Involvement of Active Oxygen

2000 Fiscal Year Final Research Report Summary

• Project/Area Number: 10680153
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 食生活
• Research Institution: Doshisha Wemen's college of Liberal Arts
• Principal Investigator: MORITA Junji Doshisha Wemen's college of Liberal Arts, Faculty of Human Life and Science, Professor, 生活科学部, 教授 (40115952)
• Project Period (FY): 1998 – 2000
• Keywords: Amino-carbonyl reaction / Peptide / Active oxygen / Nucleic acid / Browning / Chemiluminescence / Mirin

Research Abstract

The non-enzymatic browning by the amino-carbonyl reaction of oligosaccharides with amino acids, peptides, or nucleic acids, and the involvement of active oxygen in the amino-carbonyl reaction was investigated.
(1)The order of reactivity of peptides in the amino-carbonyl reaction was tripeptide > dipeptide > amino acid. The reactivity of dipeptides having common N-terminal amino acid rseidue was dependent on the reactivity of C-terminal amino acid residue. As the amino-carbonyl reaction is mainly the ionic reactions of free amino group of amino compounds with reducing sugars, the reactivity of N-terminal amino group of dipeptide is affected by the whole stereochemical configuation and the whole electric charge of dipeptdite. Color component generated from peptides showed darker color tone than that from amino acids.
(2)The reactivity of oligosaccharides in the amino-carbonyl reaction was dependent on the percentage of acyclic form of its reducing terminal saccharides in aqueous solution. Subustituents affect the stability of cyclic form of reducing terninal saccharides.
(3)Reducing sugars including oligosaccharides underwent the non-enzymatic browning by the amino-carbonyl reaction with nucleic acids such as 2'-deoxyguanosine 5'-monophosphate.
(4)The amino-carbonyl reaction of reducing sugars with amino acids or nucleic acids was stimulated by transition metal ions, and partially inhibited by SOD, catalase, chelating agents.The amount of active oxygens (hydrogen peroxide, hydroxyl radicals), produced by autoxidation of reducing sugars including oligosaccharides, is relative to the reactivity in the amino-carbonyl reaction of reducing sugars with amino acids or nucleic acids. These results indicates that active oxygens are involved in the amino-carbonyl reaction.
(5)The amount of chemiluminescence generated from "mirin", a japanese seasoning fermented rice with rice-koji, increased with the time of storage, and the increasing occurs prior for browning of "mirin". Chemiluminescence is generated by free radicals produced during the amino-carbonyl reaction. The amount of chemiluminescence is a usefull indication of browning through amino-carbonyl reaction of "mirin".