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Volume 250, Issue 1 p. 177-183
Free Access

Development and Evaluation of Peptide-Based Prolyl Oligopeptidase Inhibitors — Introduction of N-Benzyloxycarbonyl-Prolyl-3-Fluoropyrrolidine as a Lead in Inhibitor Design

Filip Goossens

Filip Goossens

Laboratory for Medical Biochemistry, University of Antwerp, Belgium

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Greet Vanhoof

Greet Vanhoof

Laboratory for Medical Biochemistry, University of Antwerp, Belgium

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Ingrid De Meester

Ingrid De Meester

Laboratory for Medical Biochemistry, University of Antwerp, Belgium

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Koen Augustyns

Koen Augustyns

Laboratory for Pharmaceutical Chemistry, University of Antwerp, Belgium

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Marjan Borloo

Marjan Borloo

Laboratory for Pharmaceutical Chemistry, University of Antwerp, Belgium

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Dirk Tourwe

Dirk Tourwe

Laboratory for Organic Chemistry, University of Brussels, Belgium

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Achiel Haemers

Achiel Haemers

Laboratory for Pharmaceutical Chemistry, University of Antwerp, Belgium

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Simon Scharpé

Corresponding Author

Simon Scharpé

Laboratory for Medical Biochemistry, University of Antwerp, Belgium

S. Scharpé, Universiteitsplein 1, S-6, B-2610 Wilrijk, Belgium
Fax:+32 3 820 27 45.Search for more papers by this author
First published: 23 June 2004
Citations: 13

Abstract

The current study has been undertaken to develop new and biocompatible inhibitors for prolyl oligopeptidase, a highly specific endopeptidase, proposed to be involved, through its affinity for neuropeptides and kinins, in the processes of learning and memory and in the control of blood pressure. For in vitro evaluation of the inhibitors, human platelet prolyl oligopeptidase was purified to homogeneity and characterized. Northern blot analysis showed that mRNA coding for prolyl oligopeptidase was present in all tissues examined and only one transcript of 3.1 kb was detected. In addition to the human platelet enzyme, we also purified rat brain prolyl oligopeptidase, which proved to have the same characteristics as the human enzyme. In a series of tested peptides, bradykinin was found to be the best substrate. Based on this information, peptides bearing pseudopeptide bonds were generated and evaluated as inhibitors. The experiments clearly demonstrated that changes to the scissile peptide bond significantly decrease the affinity of prolyl oligopeptidase for the peptide derivatives. In our series of synthetic N-terminal blocked dipeptides, N-benzyloxycarbonyl-prolyl-3-fluoropyrrolidine was the most potent compound. Inhibition was reversible, but the inhibitor was bound tightly. Calculation of its Ki according to Henderson [Henderson, J. P. (1972) Biochem. J. 127, 321–333] yielded a value of 0.8 nM. This compound was not cytotoxic in a cell culture system and inhibited the purified prolyl oligopeptidase from rat as well as from human origin. In vivo evaluation in male Whistar rats showed no acute toxicity. 5 h after administration, the most profound decrease in prolyl oligopeptidase activity was found in the thymus, brain, and testis. This study demonstrates that N-benzyloxycarbonyl-prolyl-3-fluoropyrrolidine is a potent inhibitor and a promising compound suitable to investigate the physiologic function of the enzyme in vitro and In vivo.

Abbreviations

  • C1HgBzOH
  • p-chloromercuribenzoic acid
  • iPr2P-F
  • diisopropyl fluorophosphate
  • Me2SO
  • dimethyl sulphoxide
  • NHMec
  • 7-amino-4-metbylcoumarin
  • PhMeSO2F
  • phenylmethylsulphonyl fluoride
  • Tic
  • l-1,2,3,4-tetrahydrolsoquinoline-3-carboxylic acid
  • Z-
  • N-benzyl-oxycarbonyl-
  • Z-Gly-Pro-NHMec
  • N-benzyloxycarbonyl-glycyl-prolyl-7-amino-4-methylcoumarin
  • Z-Pro-prolinal
  • N-benzyloxycarbonyl-prolyl-prolinal
  • Z-thiopro-thioprolinal
  • N-benzyloxycarbonyl-thioprolyl-thioprolinal
  • t-Boc
  • tertiary butyloxycarbonyl
  • Enzymes

  •  
  • Prolyl oligopeptidase (EC 3.4.21.26)
  •  
  • serine-type carboxy peptidase (EC 3.4.16.1)