title: beta-Aspartyl-epsilon-lysine, a peptide of the fecal contents of axenic mice.
abstract: Small quantities of low-molecular weight peptides have been characterized in the feces of axenic mice. In fecal material of axenic mice fed an autoclaved synthetic (SN) diet, we isolated a dipeptide and characterized its structure as beta-aspartyl-epsilon-lysine. This product was also present in the feces of gnotobiotic mice harbouring Clostridium perenne. We could not detect the product in the fecal contents of holoxenic mice, Clostridium difficile-contaminated mice or axenic mice fed the irradiated SN diet. The peptide, beta-aspartyl-epsilon-lysine, was produced by heating proteins during sterilization, causing the formation of a pseudopeptide bond between the epsilon-amino group of lysine and the amide group of asparagine. The intestinal strains seemed to differ in their ability to split this pseudopeptide bond in vivo.
mesh_terms: D000818:Animals; D003013:Clostridium / Q000378:metabolism; D004151:Dipeptides / Q000302:isolation & purification*; D005243:Feces / Q000032:analysis* / Q000382:microbiology; D005526:Food, Formulated; D005856:Germ-Free Life; D051379:Mice
chemical_list: D004151:Dipeptides; C038815:aspartyllysine