FRAGMENTATION OF CERULOPLASMIN FOLLOWING NONENZYMATIC GLYCATION REACTION

Bovine ceruloplasmin underwent fragmentation following non-enzymatic g lycosylation. Western blot and ELISA analyses indicated that a polyclo nal rabbit antiserum to hexitollysine reacted with bovine ceruloplasmi n after incubation with 0.1 M glucose, The same fragmentation was seen upon exposure of the protein to a hydrogen peroxide bolus, Both catal ase and EDTA blocked peroxide-dependent fragmentation, Incubation with glucose resulted in a time-dependent release of Cu2+, The released Cu 2+ appeared to participate in a Fenton-type reaction to produce hydrox yl radicals, which effected the fragmentation, Hydroxyl radical scaven gers such as thiourea, mannitol, methionine, and formate inhibited thi s cleavage, ESR spectral studies also supported participation of hydro xyl radicals, Inhibition by EDTA of the fragmentation induced by an H2 O2 bolus also supports a role for copper in a Fenton-type reaction, Ta ken together these results suggest that reactive oxygen species, such as superoxide anion and H2O2, were formed by the Maillard reaction whi ch led to hydroxyl radicals being produced by a copper-dependent Fento n-type reaction, Both processes are likely to be involved in the fragm entation of ceruloplasmin.