| 1. |
- Arsov, Zoran, et al.
(author)
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Cholesterol prevents interaction of the cell-penetrating peptide transportan with model lipid membranes
- 2008
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In: Journal of Peptide Science. - : Wiley. - 1075-2617 .- 1099-1387. ; 14:12, s. 1303-1308
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Journal article (peer-reviewed)abstract
- Interaction of the cell-penetrating peptide (CPP) cysteine-transportan (Cys-TP) with model lipid membranes was examined by spin-label electron paramagnetic resonance (EPR). Membranes were labeled with lipophilic spin probes and the influence of Cys-TP on membrane structure Was studied. The influence of Cys-TP on membrane permeability was monitored by the reduction of a liposome-trapped water-soluble spin probe. Cys-TP caused lipid ordering in membranes prepared from pure dimyristoylphosphatidylcholine (DMPC) and in DMPC membranes with moderate cholesterol concentration. In addition, Cys-TP caused a large increase in permeation of DMPC membranes. In contrast, with high cholesterol content, at which model lipid membranes are in the so-called liquid-ordered phase, no effect. of Cys-TP was observed, either on Line membrane structure or on the membrane permeability. The interaction between Cys-TP and the lipid membrane therefore depends on the lipid phase. This could be of great. importance for understanding of the CPP-lipid interaction in laterally heterogeneous membranes, white it implies that the CPP-lipid interaction can be different at different points along the membrane.
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| 2. |
- Axén, Andreas, et al.
(author)
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Cyclic insulin-regulated aminopeptidase (IRAP)/AT(4) receptor ligands
- 2006
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In: Journal of Peptide Science. - : Wiley. - 1075-2617 .- 1099-1387. ; 12:11, s. 705-713
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Journal article (peer-reviewed)abstract
- The angiotensin IV receptor (AT(4) receptor) is the insulin-regulated aminopeptidase enzyme (IRAP, EC 3.4.11.3). This membrane-spanning enzyme belongs to the M1 family of zinc-dependent metallo-peptidases. It has been proposed that AT4 receptor ligands exert their physiological effects by binding to the active site of IRAP and thereby inhibiting the catalytic activity of the enzyme. The biological activity of a large series of linear angiotensin IV analogs was previously disclosed. Herein, the synthesis and biological evaluation of a series of angiotensin IV analogs, encompassing macrocyclic ring systems of different sizes, are presented. It is demonstrated that disulfide cyclizations of angiotensin IV can deliver ligands with high IRAP/AT4 receptor affinity. One ligand, with an 11-membered ring system (4), inhibited human IRAP and aminopeptidase N (AP-N) activity with similar potency as angiotensin IV but was considerably more stable than angiotensin IV toward enzymatic degradation. The compound provides a promising starting point for further optimization toward more drug-like derivatives. The cyclic constrained analogs allowed us to propose a tentative bioactive conformation of angiotensin IV and it seems that the peptide adopts an inverse gamma-turn at the C-terminal.
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| 3. |
- Axén, Andreas, et al.
(author)
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Small potent ligands to the insulin-regulated aminopeptidase (IRAP)/AT(4) receptor
- 2007
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In: Journal of Peptide Science. - : Wiley. - 1075-2617 .- 1099-1387. ; 13:7, s. 434-444
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Journal article (peer-reviewed)abstract
- Angiotensin IV analogs encompassing aromatic scaffolds replacing parts of the backbone of angiotensin IV have been synthesized and evaluated in biological assays. Several of the ligands displayed high affinities to the insulin-regulated aminopeptidase (IRAP)/AT4 receptor. Displacement of the C-terminal of angiotensin IV with an o-substituted aryl acetic acid derivative delivered the ligand 4, which exhibited the highest binding affinity (Ki = 1.9 nM). The high affinity of this ligand provides support to the hypothesis that angiotensin IV adopts a -turn in the C-terminal of its bioactive conformation.Ligand (4) inhibits both human IRAP and aminopeptidase N-activity and induces proliferation of adult neural stem cells at low concentrations. Furthermore, ligand 4 is degraded considerably more slowly in membrane preparations than angiotensin IV. Hence, it might constitute a suitable research tool for biological studies of the (IRAP)/AT4 receptor.
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| 8. |
- Ericsson, Daniel J., et al.
(author)
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Identification of small peptides mimicking the R2 C-terminus of Mycobacterium tuberculosis ribonucleotide reductase
- 2010
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In: Journal of Peptide Science. - : Wiley. - 1075-2617 .- 1099-1387. ; 16:3, s. 159-164
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Journal article (peer-reviewed)abstract
- Ribonucleotide reductase (RNR) is a viable target for new drugs against the causative agent of tuberculosis, Mycobacterium tuberculosis. Previous work has shown that an N-acetylated heptapeptide based on the C-terminal sequence of the smaller RNR subunit can disrupt the formation of the holoenzyme sufficiently to inhibit its function. Here the synthesis and binding affinity, evaluated by competitive fluorescence polarization, of several truncated and N-protected peptides are described. The protected single-amino acid Fmoc-Trp shows binding affinity comparable to the N-acetylated heptapeptide, making it an attractive candidate for further development of non-peptidic RNR inhibitors.
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| 9. |
- Forde, Eanna, et al.
(author)
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Action of antimicrobial peptides and their prodrugs on model and biological membranes
- 2018
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In: Journal of Peptide Science. - : WILEY. - 1075-2617 .- 1099-1387. ; 24:7
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Journal article (peer-reviewed)abstract
- Antimicrobial peptides (AMPs) are promising broad-spectrum antibiotic candidates in the wake of multi-drug resistant pathogens. Their clinical use still requires a solution based on lead optimisation and/ or formulation to overcome certain limitations, such as unwanted cytotoxicity. A prodrug approach could overcome this safety barrier and can be achieved through reversible reduction or neutralisation of the AMPs' net cationic charge. By prodrug activation through pathogen associated enzymes, this approach could increase the therapeutic index of membrane active peptides. P18, a cecropin/ magainin hybrid, and WMR, a myxinidin analogue from hagfish, were used as templates for the design strategy. The membrane permeabilizing activities of these AMPs and their prodrugs are reported here for liposomes of either Escherichia coli polar lipid extract or a human model lipid system of phosphatidylcholine and cholesterol. These results are compared with their antibacterial and haemolytic activities. Overall, correlation between liposome permeabilization and the corresponding bioactivity is observed and indicate that the broad-spectrum antibacterial effect exerted by these peptides is associated with membrane disruption. Furthermore, the prodrug modification had a general negative influence on membrane disruption and bioactivity, notably as much on bacterial as on human membranes. This prodrug strategy is particularly successful when complete neutralisation of the AMP's net charge occurs. Thus, on-target selectivity between bacterial and human membranes can be improved, which may be used to prevent the unnecessary exposure of host cells and commensal bacteria to active AMPs.
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