Are diprotin A (Ile-Pro-Ile) and diprotin B (Val-Pro-Leu) inhibitors or substrates of dipeptidyl peptidase IV?
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.
Rahfeld
J
J
Martin-Luther-University, Biotechnikum Halle, F.R.G.
Schierhorn
M
M
Hartrodt
B
B
Neubert
K
K
Heins
J
J
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
D009842:Oligopeptides; C041445:diprotin A; C041446:diprotin B; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; D018819:Dipeptidyl Peptidase 4