EVIDENCE FOR EXCRETION OF GLYCATION AGENTS FROM E-COLI CELLS DURING GROWTH

Recently we have hypothesised that bacteria might have some Protective mechanism for elimination of highly reactive carbonyl (glycating) compounds out of the cell (3). To check this hypothesis, we have studied here the ability of bacterial culture media obtained after overnight cultivation of E. coli AB 1157 cells to glycate a lysine rich protein (histone HI). Four different methods were applied for identification of glycation products in the reporter protein: fluorescence spectroscopy, ELISA, polyacrylamide gel electrophoresis (PAGE) and determination of reactive carbonyl groups. The obtained results showed an increased fluorescence at lambda(cm) = 440 nm upon excitation at 370 mn (specific for the advanced glycation end products, AGEs), elevated content of reactive carbonyls in the reporter protein and immunoreactivity with an imidazolone specific monoclonal antibody. PAGE also revealed changes in the treated histone HI (fragmentation and covalent aggregation) which were typical for glycated proteins. All these together make it reasonable to conclude that the bacterial culture media contain reactive glycating compounds excreted from the E. coli cells during their growth.