1.Synthesis of new (-)-bestatin-based inhibitor libraries reveals a novel binding mode in the S1 pocket of the essential malaria M1 metalloaminopeptidase.
Velmourougane G1, Harbut MB, Dalal S, McGowan S, Oellig CA, Meinhardt N, Whisstock JC, Klemba M, Greenbaum DC. J Med Chem. 2011 Mar 24;54(6):1655-66. doi: 10.1021/jm101227t. Epub 2011 Mar 2.
The malarial PfA-M1 metallo-aminopeptidase is considered a putative drug target. The natural product dipeptide mimetic, bestatin, is a potent inhibitor of PfA-M1. Herein we present a new, efficient, and high-yielding protocol for the synthesis of bestatin derivatives from natural and unnatural N-Boc-d-amino acids. A diverse library of bestatin derivatives was synthesized with variants at the side chain of either the α-hydroxy-β-amino acid (P1) or the adjacent natural α-amino acid (P1'). Surprisingly, we found that extended aromatic side chains at the P1 position resulted in potent inhibition against PfA-M1. To understand these data, we determined the X-ray cocrystal structures of PfA-M1 with two derivatives having either a Tyr(OMe) 15 or Tyr(OBzl) 16 at the P1 position and observed substantial inhibitor-induced rearrangement of the primary loop within the PfA-M1 pocket that interacts with the P1 side chain. Our data provide important insights for the rational design of more potent and selective inhibitors of this enzyme that may eventually lead to new therapies for malaria.
2.Pro-VGF-derived peptides induce penile erection in male rats: Involvement of paraventricular nitric oxide.
Succu S1, Mascia MS, Melis T, Sanna F, Melis MR, Possenti R, Argiolas A. Neuropharmacology. 2005 Dec;49(7):1017-25. Epub 2005 Aug 8.
The effect of four peptides derived from the C-terminal portion of rat pro-VGF(556-617) (VGF(556-576), VGF(588-617), VGF(599-617), and VGF(588-597)), on penile erection and nitric oxide production in the paraventricular nucleus of the hypothalamus was studied in male rats after injecting into this hypothalamic nucleus. VGF(588-617) (0.5, 1 and 2 microg), VGF(599-617) (0.5, 2 and 5 microg) and, to a lower extent, VGF(588-597) (2 and 5 microg) induced penile erection episodes when injected into the paraventricular nucleus and concomitantly increased paraventricular nitric oxide production, while VGF(556-576) (5 microg) was ineffective. VGF(588-617)-induced nitric oxide production was reduced by N(G)-nitro-l-arginine methylester (l-NAME) (20 microg), a nitric oxide synthase inhibitor, which also reduced penile erection when injected in the paraventricular nucleus 15 min before the VGF peptide. The oxytocin receptor antagonist d(CH(2))(5)Tyr(Me)-Orn(8)-vasotocin (1 microg) also effectively reduced VGF(588-617)-induced penile erection when given into the lateral ventricles, but not when injected into the paraventricular nucleus.
3.Biological activity of for-Met-Leu-Phe-OMe analogs: relevant substitutions specifically trigger killing mechanisms in human neutrophils.
Cavicchioni G1, Fraulini A, Turchetti M, Varani K, Falzarano S, Pavan B, Spisani S. Eur J Pharmacol. 2005 Apr 4;512(1):1-8.
Two analogs of the prototypical peptide for-Met-Leu-Phe-OMe (fMLP-OMe), for-Gln-Tyr-Phe-OMe (1) and for-Gln-Tyr-Tyr-OMe (2), carrying unusual hydrophilic residues, were synthesized in order to investigate whether they provoked specific biological responses, as well as intracellular calcium mobilization, in human neutrophils. Whereas neither compound stimulates chemotaxis, both are able to elicit lysosomal enzyme production. However compound 1 is able to trigger copious superoxide anion production while compound 2 only elicits minor superoxide anion production. In binding experiments on formylpeptide receptors, the newly synthesized compounds for-Gln-Tyr-Phe-OMe (1) and for-Gln-Tyr-Tyr-OMe (2) showed affinity values in the micromolar range. These derivatives demonstrate inability to find a positive contribute from single substitutions. A very important result of this research is the evidence of the ability of the formyl group alone to trigger the primary target of the human neutrophil activity, i.
4.Adaptation to pregnancy leads to attenuated rat uterine artery smooth muscle sensitivity to oxytocin.
Vedernikov YP1, Betancourt A, Wentz MJ, Saade GR, Garfield RE. Am J Obstet Gynecol. 2006 Jan;194(1):252-60.
OBJECTIVE: We tested the hypothesis that oxytocin (OT) contracts blood vessels via vasopressin V1A (VP) receptors, and that this depends on pregnancy.