ISSN:
1438-2199
Keywords:
Amino acids
;
Aminoethylcysteine
;
Ketimines
;
Iron chelates
;
Autoxidation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary Oxidation of aminoethylcysteine ketimine (AECK) is followed by the change of 296nm absorbance, by the O2 consumption and by the HPLC analysis of the oxidation products. The oxidation is strongly inhibited by the addition of superoxide dismutase (SOD) but not by hydroxyl radical scavengers or catalase. Addition of EDTA or o-phenanthroline (OPT) favours the oxidation, probably by keeping contaminating metals in solution at the pH studied. Addition of Fe3+ ions strongly accelerates the oxidation in the presence of EDTA or OPT. AECK reacts stoichiometrically with OPT-Fe3+ complex producing the Fe2+ complex which is not reoxidised by bubbling O2. HPLC analyses of the final oxidation products reacting with 2,4-dinitrophenylhydrazine (DNPH) confirm the AECK sulfoxide as the main product of the slow spontaneous oxidation. The detection of other oxidation products when the reaction is speeded up by the addition of the OPT-Fe3+ complex, suggests that the oxidation takes place essentially on the carbon portion of the AECK molecule in the side of the double bond. On the basis of the results presented here, a scheme of reactions is illustrated which starts with the transfer of one electron from AECK to a contaminating metal ion (possibly Fe3+) producing the radical AECK• as the initiator of a self propagating reaction. The radical AECK• reacting with O2 starts a series of reactions accounting for most of the products detected.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00805865
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