Browsing by Author "ALMARZA, C"

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    PHOTOREACTIONS OF RIBOFLAVIN WITH SPERMINE AND THEIR ROLE IN TRYPTOPHAN PHOTOCONSUMPTION INDUCED BY RIBOFLAVIN
    (ELSEVIER SCIENCE SA, 1993) SILVA, E; ALMARZA, C; BERNDT, D; LARRONDO, L; LISSI, E
    The influence of spermine (Spr) on riboflavin (Rb) and riboflavin-tryptophan (Rb-Trp) solutions irradiated at 450 nm under aerobic and anaerobic conditions was studied. In both systems, it is shown that Spr interacts with 3Rb probably giving spermine-derived and flavin-derived radicals. In the presence of oxygen, modified Rb is regenerated with the simultaneous production of the active oxygen species O2.- and/or HO2.. The addition of Spr to the Rb-Trp system under aerobic conditions leads to a small protection of Trp consumption, although oxygen consumption is increased. This small protection arises as a consequence of competitive interaction of Trp and Spr with 3Rb. The competition of Spr and oxygen for 3Rb could also explain the autocatalytic oxygen consumption observed in the presence of the amine. Under anaerobic conditions Spr produces a larger protection of Trp consumption, which is compatible with the larger Rb triplet lifetime expected under these conditions.