Are diprotin A (Ile-Pro-Ile) and diprotin B (Val-Pro-Leu) inhibitors or substrates of dipeptidyl peptidase IV?

  • Biochim Biophys Acta. 1991 Jan 29;1076(2):314-6. doi: 10.1016/0167-4838(91)90284-7.
J Rahfeld  1 ,  M Schierhorn ,  B Hartrodt ,  K Neubert ,  J Heins
Affiliations
  • 1. Martin-Luther-University, Biotechnikum Halle, F.R.G.
PMID: 1671823 DOI: 10.1016/0167-4838(91)90284-7
Abstract

Dipeptidyl Peptidase IV preferably hydrolyzes peptides and proteins with a penultimate proline residue. Umezawa and co-workers (Umezawa et al. (1984) J. Antibiotics 37, 422-425) reported that diprotin A (Ile-Pro-Ile) and diprotin B (Val-Pro-Leu) are inhibitors for Dipeptidyl Peptidase IV. We could show that both compounds as well as Other tripeptides with a penultimate proline residue are substrates for Dipeptidyl Peptidase IV. An apparent competitive inhibition by those compounds is a kinetic artifact due to the substrate-like structure of such tripeptides.

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