Determination of beta-aspartylpeptidase activity in human faeces by high-performance liquid chromatography using pre-column derivatization with phenyl isothiocyanate.
Bacterial enzymes are responsible for degradation of beta-aspartyl peptides in the intestinal tract. These peptides, especially the dipeptide beta-aspartylglycine, are useful as indicators of an impaired anaerobic intestinal microflora of antibiotic-treated patients. A method to separate the dipeptides beta-aspartylalanine, beta-aspartylglutamine, beta-aspartylglycine and beta-aspartylserine, using reversed-phase high-performance liquid chromatography and precolumn derivatization with phenyl isothiocyanate, was developed. This method was used to determine beta-aspartylpeptidase activity in faecal supernatants of healthy human volunteers and antibiotic-treated patients with beta-aspartylglycine as substrate. This activity was absent in the antibiotic-treated group, while in individuals with an intact intestinal flora it ranged from 16 to 100% degradation per 18 h. In addition, it was found that faecal enzyme preparations cleaved beta-aspartylglycine at a much lower rate than the other beta-aspartyl peptides.
D000596:Amino Acids / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D004150:Dipeptidases / Q000032:analysis*; D005243:Feces / Q000201:enzymology*; D006801:Humans; D007422:Intestines / Q000382:microbiology; D017879:Isothiocyanates; D013861:Thiocyanates
D000596:Amino Acids; D017879:Isothiocyanates; D013861:Thiocyanates; C005441:phenylisothiocyanate; D004150:Dipeptidases; C051396:beta-aspartyl peptidase