Increased excretion of proline-containing peptides in dipeptidyl peptidase IV-deficient rats

We have reported that a substrain of Fischer 344 rat exhibits a deficiency of dipeptidyl peptidase IV (Watanabe et al. Experientia 43: 400-401, 1987). In this study, this rat model was found to excrete large amounts of proline-containing peptides in the urine. The peptide fraction also contained other amino acids, such as hydroxyproline and glycine. The results indicate that the enzyme might be involved in the metabolism of collagens and related peptides.