title: Are diprotin A (Ile-Pro-Ile) and diprotin B (Val-Pro-Leu) inhibitors or substrates of dipeptidyl peptidase IV?
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.
authors.affiliation: Martin-Luther-University, Biotechnikum Halle, F.R.G.
authors.forename: J
authors.initials: J
authors.lastname: Rahfeld
authors.forename: M
authors.initials: M
authors.lastname: Schierhorn
authors.forename: B
authors.initials: B
authors.lastname: Hartrodt
authors.forename: K
authors.initials: K
authors.lastname: Neubert
authors.forename: J
authors.initials: J
authors.lastname: Heins
mesh_terms: D000595:Amino Acid Sequence; D018819:Dipeptidyl Peptidase 4; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000378:metabolism* / Q000494:pharmacology; D013379:Substrate Specificity
chemical_list: D009842:Oligopeptides; C041445:diprotin A; C041446:diprotin B; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D018819:Dipeptidyl Peptidase 4