A Global Potential Analysis of the 16^{16}O+28^{28}Si Reaction Using a New Type of Coupling Potential

A new approach has been used to explain the experimental data for the $^{16}$O+$^{28}$Si system over a wide energy range in the laboratory system from 29.0 to 142.5 MeV. A number of serious problems has continued to plague the study of this system for a couple of decades. The explanation of anomalous large angle scattering data; the reproduction of the oscillatory structure near the Coulomb barrier; the out-of-phase problem between theoretical predictions and experimental data; the consistent description of angular distributions together with excitation functions data are just some of these problems. These are long standing problems that have persisted over the years and do represent a challenge calling for a consistent framework to resolve these difficulties within a unified approach. Traditional frameworks have failed to describe these phenomena within a single model and have so far only offered different approaches where these difficulties are investigated separately from one another. The present work offers a plausible framework where all these difficulties are investigated and answered. Not only it improves the simultaneous fits to the data of these diverse observables, achieving this within a unified approach over a wide energy range, but it departs for its coupling potential from the standard formulation. This new feature is shown to improve consistently the agreement with the experimental data and has made major improvement on all the previous coupled-channels calculations for this system.Comment: 21 pages with 12 figure

Isolation and biochemical characterization of bradykinin-potentiating peptides from Bitis gabonica rhinoceros

Abstract Background Venoms represent a still underexplored reservoir of bioactive components that might mitigate or cure diseases in conditions in which conventional therapy is ineffective. The bradykinin-potentiating peptides (BPPs) comprise a class of angiotensin-I converting enzyme (ACE) inhibitors. The BPPs usually consist of oligopeptides with 5 to 13 residues with a high number of proline residues and the tripeptide Ile-Pro-Pro (IPP-tripeptide) in the C-terminus region and have a conserved N-terminal pyroglutamate residue. As a whole, the action of the BPPs on prey and snakebite victims results in the decrease of the blood pressure. The aim of this work was to isolate and characterize novel BPPs from the venom of Bitis gabonica rhinoceros. Methods The crude venom of B. g. rhinoceros was fractionated by size exclusion chromatography and the peptide fraction (<7 kDa) was separated by reverse phase chromatography (RP-HPLC) and analyzed by ESI-IT-TOF-MS/MS. One new BPP was identified, synthetized and assayed for ACE inhibition and, in vivo, for edema potentiation. Results Typical BPP signatures were identified in three RP-HPLC fractions. CID fragmentation presented the usual y-ion of the terminal P-P fragment as a predominant signal at m/z 213.1. De novo peptide sequencing identified one Bothrops-like BPP and one new BPP sequence. The new BPP was synthesized and showed poor inhibition over ACE, but displayed significant bradykinin-induced edema potentiation. Conclusions So far, few BPPs are described in Viperinae, and based on the sequenced peptides, two non-canonical sequences were detected. The possible clinical role of this new peptides remains unclear

Isolation and biochemical characterization of bradykinin-potentiating peptides from Bitis gabonica rhinoceros

<div><p>Abstract Background: Venoms represent a still underexplored reservoir of bioactive components that might mitigate or cure diseases in conditions in which conventional therapy is ineffective. The bradykinin-potentiating peptides (BPPs) comprise a class of angiotensin-I converting enzyme (ACE) inhibitors. The BPPs usually consist of oligopeptides with 5 to 13 residues with a high number of proline residues and the tripeptide Ile-Pro-Pro (IPP-tripeptide) in the C-terminus region and have a conserved N-terminal pyroglutamate residue. As a whole, the action of the BPPs on prey and snakebite victims results in the decrease of the blood pressure. The aim of this work was to isolate and characterize novel BPPs from the venom of Bitis gabonica rhinoceros. Methods: The crude venom of B. g. rhinoceros was fractionated by size exclusion chromatography and the peptide fraction (<7 kDa) was separated by reverse phase chromatography (RP-HPLC) and analyzed by ESI-IT-TOF-MS/MS. One new BPP was identified, synthetized and assayed for ACE inhibition and, in vivo, for edema potentiation. Results: Typical BPP signatures were identified in three RP-HPLC fractions. CID fragmentation presented the usual y-ion of the terminal P-P fragment as a predominant signal at m/z 213.1. De novo peptide sequencing identified one Bothrops-like BPP and one new BPP sequence. The new BPP was synthesized and showed poor inhibition over ACE, but displayed significant bradykinin-induced edema potentiation. Conclusions: So far, few BPPs are described in Viperinae, and based on the sequenced peptides, two non-canonical sequences were detected. The possible clinical role of this new peptides remains unclear.</p></div

Structural and functional properties of the Kunitz-type and C-terminal domains of Amblyomin-X supporting its antitumor activity

International audienceAmblyomin-X is a Kunitz-type FXa inhibitor identified through the transcriptome analysis of the salivary gland from Amblyomma sculptum tick. This protein consists of two domains of equivalent size, triggers apoptosis in different tumor cell lines, and promotes regression of tumor growth, and reduction of metastasis. To study the structural properties and functional roles of the N-terminal (N-ter) and C-terminal (C-ter) domains of Amblyomin-X, we synthesized them by solid-phase peptide synthesis, solved the X-Ray crystallographic structure of the N-ter domain, confirming its Kunitz-type signature, and studied their biological properties. We show here that the C-ter domain is responsible for the uptake of Amblyomin-X by tumor cells and highlight the ability of this domain to deliver intracellular cargo by the strong enhancement of the intracellular detection of molecules with low cellular-uptake efficiency (p15) after their coupling with the C-ter domain. In contrast, the N-ter Kunitz domain of Amblyomin-X is not capable of crossing through the cell membrane but is associated with tumor cell cytotoxicity when it is microinjected into the cells or fused to TAT cell-penetrating peptide. Additionally, we identify the minimum length C-terminal domain named F2C able to enter in the SK-MEL-28 cells and induces dynein chains gene expression modulation, a molecular motor that plays a role in the uptake and intracellular trafficking of Amblyomin-X

Relationship between autophagy marker expression and dynein in the mechanism of action of Amblyomin-X.

<p>Representative western blots of whole-cell lysates of cultured cells treated with vehicle (PBS), 0.5 µM Ambly for 2 h, 4 h or 24 h, 5 µM MG-132 for 24 h or 0.2 µM rapamycin for 16 h. Images are representative of three independent experiments containing the autophagic markers (mTOR, AMBRA1, LC3-I and LC3-II) in <b>A</b>) SK-MEL-28 cells and (<b>B</b>) MIA PaCa-2 cells and (<b>C</b>) autophagic/apoptosis marker (Bim) in SK-MEL-28 cells and (<b>D</b>) MIA PaCa-2 cells. Confocal microscopy analysis of cultured cells treated with vehicle (PBS) or 0.5 µM Ambly for 24 h. The final overlay image represents five fields of three independent experiments in which (<b>E</b>) the red fluorescence represents HC1, while the green fluorescence represents mTOR and the merging of the two is in yellow; or (<b>F</b>) the red fluorescence represents LC8-1/2, while the green fluorescence represents AMBRA1 (originally, the yellow fluorescence was artificially colored by the microscope software) and the merging of the two is in yellow; or (<b>G</b>) the red fluorescence represents LC8-1/2, while the green fluorescence represents Bim and the merging of the two is in yellow.</p

K-linkage profile and visualization of autophagy steps in the mechanism of action of Amblyomin-X.

<p>(<b>A</b>) Mean fluorescence intensity obtained from histograms of flow cytometry analysis of K48 and K63 linkage. Cultured cells were treated with vehicle (PBS) or 0.5 µM Ambly for 24 h. Results are expressed as the means ± standard error in arbitrary units of three independent experiments. The criteria and representation of statistical significance were set as *p≤0.05, **p≤0.01, ***p≤0.001 or ns (non-significant). (<b>B</b>) Immunofluorescence analysis of autophagic membrane formation. Cultured cells were treated with vehicle (PBS), 5 µM MG-132 for 24 h, 0.2 µM rapamycin for 16 h or 0.5 µM Ambly for 24 h or 48 h. LC3 was stained with FITC and is represented in diffused green fluorescence in the cytoplasm, while the nucleus was stained with DAPI and is represented in blue. Images are representative of five fields from each experiment (n = 3). (<b>C</b>) Fluorescence microscopy analysis using acridine orange stain. Cultured cells were treated with vehicle (PBS), 5 µM MG-132 for 24 h, 0.2 µM rapamycin for 16 h, 0.5 µM Ambly for 24 h pretreated with 0.2 µM rapamycin for 16 h (rapa/Ambly) or 0.5 µM Ambly for 24 h, 48 h or 72 h. Bright red fluorescence indicates acidic vesicles, while green fluorescence indicates the cytoplasm and nucleus. White arrows indicate the zoomed area located in the upper right position of the image. Images are representative of five fields from each experiment (n = 3). (<b>D</b>) Cell viability assay of tumor cells treated with the compounds used in autophagy visualization. Results are reported as the means ± standard error of three independent experiments. The criteria and representation of statistical significance were set as *p≤0.05, **p≤0.01, ***p≤0.001 or ns (non-significant).</p

Protein expression of dynein, NFKB1 and β-actin induced by Amblyomin-X.

<p>Representative western blots of whole-cell lysates of (<b>A</b>) dynein chains in SK-MEL-28 cells, (<b>B</b>) dynein chains in MIA PaCa-2 cells, (<b>C</b>) NFKB1 and β-actin in SK-MEL-28 cells and (<b>D</b>) NFKB1 and β-actin in MIA PaCa-2 cells. Cultured cells were treated with vehicle (PBS), 0.5 µM Ambly for 2 h, 4 h or 24 h or 5 µM MG-132 (NFKB1 and β-actin). Images are representative of three independent experiments.</p

Bradykinin-related peptides in the venom of the solitary wasp Cyphononyx fulvognathus

Bradykinin (BK) and its related peptides are widely distributed in venomous animals, including wasps. in fact, we have previously purified a novel BK-related peptide (BRP) named Cd-146 and the threonine(6)- bradykinin (Thr(6)-BK) from the venom of the solitary wasp Cyphononyx fulvognathus. Further survey of this same wasp venom extract allowed the structural characterization of two other novel BRPs, named here as fulvonin and cyphokinin. Biochemical characterization performed here showed that although the high primary structure similarity observed with BK, these wasp peptides are not good substrates for angiotensin I-converting enzyme (ACE) acting more likely as inhibitors of this enzyme. in pharmacological assays, only those more structurally similar to BK, namely cyphokinin and Thr(6)-BK, were able to promote the contraction of guinea-pig ileum smooth muscle preparations, which was completely blocked by the B(2) receptors antagonist HOE-140 in the same way as observed for BK. Only fulvonin was shown to potentiate BK-elicited smooth muscle contraction. Moreover, the 2 new wasp BRPs, namely fulvonin and cyphokinin, as well as Cd-146 and Thr(6)-BK, showed hyperalgesic effect in the rat paw pressure test after intraplantar injection. This effect was shown here to be due to the action of these peptides on BK receptors, since the hyperalgesia induced by both Cd-146 and fulvonin was blocked by B(1) receptor antagonist, while the effect of both cyphokinin and Thr(6)-BK was reversed by B(2) antagonist. This data give support to a better understanding of the function and targets of the kinin-related peptides widely found in several insect venoms. (C) 2009 Elsevier Inc. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo, Dept Pharmacol, BR-04044020 São Paulo, BrazilButantan Inst, Lab Pathophysiol, BR-05503900 São Paulo, BrazilSuntory Inst Bioorgan Res, Osaka 6188503, JapanUniversidade Federal de São Paulo, Dept Biophys, BR-04044020 São Paulo, BrazilButantan Inst, Pharmacol Lab, BR-05503900 São Paulo, BrazilButantan Inst, CAT CEPID, BR-05503900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pharmacol, BR-04044020 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Biophys, BR-04044020 São Paulo, BrazilWeb of Scienc