A kinetic study of glucagon-like peptide-1 and glucagon-like peptide-2 truncation by dipeptidyl peptidase IV, in vitro.

In vivo inactivation of glucagon-like peptide-1 (GLP-1) and glucagon-like peptide-2 (GLP-2) was found to be associated with the proteolytic removal of their N-terminal dipeptide by the ectopeptidase dipeptidyl peptidase IV (DPP IV). Previous studies suggested that the in vivo metabolism of GLP-1 is much faster than that of GLP-2. In this paper, we investigated the in vitro truncation of GLP-2 and GLP-1 by DPP IV. The slower conversion rate observed for GLP-2 compared to GLP-1 was due to an approximately 10-fold reduction in catalytic rate constant. The selectivity of DPP IV for the glucagon-like peptides was compared with data obtained for other natural substrates using the same enzyme source in identical conditions.