title: On the terminal homologation of physiologically active peptides as a means of increasing stability in human serum--neurotensin, opiorphin, B27-KK10 epitope, NPY.
abstract: The terminal homologation by CH(2) insertion into the peptides mentioned in the title is described. This involves replacement of the N-terminal amino acid residue by a β(2) - and of the C-terminal amino acid residue by a β(3) -homo-amino acid moiety (β(2) hXaa and β(3) hXaa, resp.; Fig. 1). In this way, the structure of the peptide chain from the N-terminal to the C-terminal stereogenic center is identical, and the modified peptide is protected against cleavage by exopeptidases (Figs. 2 and 3). Neurotensin (NT; 1) and its C-terminal fragment NT(8-13) are ligands of the G-protein-coupled receptors (GPCR) NT1, NT2, NT3, and NT analogs are promising tools to be used in cancer diagnostics and therapy. The affinities of homologated NT analogs, 2b-2e, for NT1 and NT2 receptors were determined by using cell homogenates and tumor tissues (Table 1); in the latter experiments, the affinities for the NT1 receptor are more or less the same as those of NT (0.5-1.3 vs. 0.6 nM). At the same time, one of the homologated NT analogs, 2c, survives in human plasma for 7 days at 37° (Fig. 6). An NMR analysis of NT(8-13) (Tables 2 and 4, and Fig. 8) reveals that this N-terminal NT fragment folds to a turn in CD(3) OH. - In the case of the human analgesic opiorphin (3a), a pentapeptide, and of the HIV-derived B27-KK10 (4a), a decapeptide, terminal homologation (→3b and 4b, resp.) led to a 7- and 70-fold half-life increase in plasma (Fig. 9). With N-terminally homologated NPY, 5c, we were not able to determine serum stability; the peptide consisting of 36 amino acid residues is subject to cleavage by endopetidases. Three of the homologated compounds, 2b, 2c, and 5c, were shown to be agonists (Fig. 7 and 11). A comparison of terminal homologation with other stability-increasing terminal modifications of peptides is performed (Fig. 5), and possible applications of the neurotensin analogs, described herein, are discussed.
authors.affiliation: Laboratorium für Organische Chemie, Departement für Chemie und Angewandte Biowissenschaften, ETH-Zürich, Hönggerberg, Wolfgang-Pauli-Strasse 10, Zürich, Switzerland. seebach@org.chem.ethz.ch
authors.forename: Dieter
authors.initials: D
authors.lastname: Seebach
authors.forename: Aneta
authors.initials: A
authors.lastname: Lukaszuk
authors.forename: Krystyna
authors.initials: K
authors.lastname: Patora-Komisarska
authors.forename: Dominika
authors.initials: D
authors.lastname: Podwysocka
authors.forename: James
authors.initials: J
authors.lastname: Gardiner
authors.forename: Marc-Olivier
authors.initials: MO
authors.lastname: Ebert
authors.forename: Jean Claude
authors.initials: JC
authors.lastname: Reubi
authors.forename: Renzo
authors.initials: R
authors.lastname: Cescato
authors.forename: Beatrice
authors.initials: B
authors.lastname: Waser
authors.forename: Peter
authors.initials: P
authors.lastname: Gmeiner
authors.forename: Harald
authors.initials: H
authors.lastname: Hübner
authors.forename: Catherine
authors.initials: C
authors.lastname: Rougeot
mesh_terms: D000595:Amino Acid Sequence; D040761:Biomimetic Materials / Q000737:chemistry / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D020689:Exopeptidases / Q000378:metabolism; D006678:HIV / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009478:Neuropeptide Y / Q000737:chemistry* / Q000378:metabolism; D009496:Neurotensin / Q000031:analogs & derivatives* / Q000378:metabolism; D009842:Oligopeptides / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D055550:Protein Stability; D018028:Receptors, Neurotensin / Q000378:metabolism; D012471:Salivary Proteins and Peptides / Q000737:chemistry* / Q000378:metabolism; D044967:Serum / Q000378:metabolism*; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D009478:Neuropeptide Y; D009842:Oligopeptides; D018028:Receptors, Neurotensin; D012471:Salivary Proteins and Peptides; D014764:Viral Proteins; C517879:glutaminyl-arginyl-phenylalanyl-seryl-arginine; D009496:Neurotensin; D020689:Exopeptidases