Publications by authors named "Helene Amatdjais-Groenen"

Bacterial biofilms represent an escalating global health concern with the proliferation of drug resistance and hospital-acquired infections annually. Numerous strategies are under exploration to combat biofilms and preempt the development of antibacterial resistance. Among these, mechanical disruption of biofilms and enclosed bacteria presents a promising avenue, aiming to induce membrane permeabilization and consequent lethal damage.

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The development of new antipsychotics with pro-cognitive properties and less side effects represents a priority in schizophrenia drug research. In this study, we present for the first time a preclinical exploration of the effects of the promising natural atypical antipsychotic Methyl-2-Amino-3- Methoxybenzoate (MAM), a brain-penetrable protoalkaloid from the seed of the plant Nigella damascena. Using animal models related to hyperdopaminergic activity, namely the pharmacogenetic apomorphine (D2/D1 receptor agonist)-susceptible (APO-SUS) rat model and pharmacologically induced mouse and rat models of schizophrenia, we found that MAM reduced gnawing stereotypy and climbing behaviours induced by dopaminergic agents.

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Purpose: Incomplete resection of prostate cancer (PCa) results in increased risk of disease recurrence. Combined fluorescence-guided surgery with tumor-targeted photodynamic therapy (tPDT) may help to achieve complete tumor eradication. We developed a prostate-specific membrane antigen (PSMA) ligand consisting of a DOTA chelator for In labeling and a fluorophore/photosensitizer IRDye700DX (PSMA-N064).

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Dengue is an important arboviral infectious disease for which there is currently no specific cure. We report gemini-like (geminoid) alkylated amphiphilic peptides containing lysines in combination with glycines or alanines (CHC(O)-Lys-(Gly or Ala)Lys-NHCH, shorthand notation C-KXK-C with X = A or G, and = 0-2). The representatives with 1 or 2 Ala inhibit dengue protease and human furin, two serine proteases involved in dengue virus infection that have peptides with cationic amino acids as their preferred substrates, with IC values in the lower µM range.

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Introduction: The first generation ligands for prostate-specific membrane antigen (PSMA)-targeted radio- and fluorescence-guided surgery followed by adjuvant photodynamic therapy (PDT) have already shown the potential of this approach. Here, we developed three new photosensitizer-based dual-labeled PSMA ligands by crucial modification of existing PSMA ligand backbone structures (PSMA-1007/PSMA-617) for multimodal imaging and targeted PDT of PCa.

Methods: Various new PSMA ligands were synthesized using solid-phase chemistry and provided with a DOTA chelator for In labeling and the fluorophore/photosensitizer IRDye700DX.

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Strain-promoted azide-alkyne cycloaddition (SPAAC) is a straightforward and multipurpose conjugation strategy. The use of SPAAC to link different functional elements to prostate-specific membrane antigen (PSMA) ligands would facilitate the development of a modular platform for PSMA-targeted imaging and therapy of prostate cancer (PCa). As a first proof of concept for the SPAAC chemistry platform, we synthesized and characterized four dual-labeled PSMA ligands for intraoperative radiodetection and fluorescence imaging of PCa.

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Incomplete resection of prostate cancer (PCa) occurs in 15%-50% of PCa patients. Disease recurrence negatively impacts oncological outcome. The use of radio-, fluorescent-, or photosensitizer-labeled ligands to target the prostate-specific membrane antigen (PSMA) has become a well-established method for the detection and treatment of PCa.

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Methylation of lysine residues in histone proteins is catalyzed by S-adenosylmethionine (SAM)-dependent histone lysine methyltransferases (KMTs), a genuinely important class of epigenetic enzymes of biomedical interest. Here we report synthetic, mass spectrometric, NMR spectroscopic and quantum mechanical/molecular mechanical (QM/MM) molecular dynamics studies on KMT-catalyzed methylation of histone peptides that contain lysine and its sterically demanding analogs. Our synergistic experimental and computational work demonstrates that human KMTs have a capacity to catalyze methylation of slightly bulkier lysine analogs, but lack the activity for analogs that possess larger aromatic side chains.

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Article Synopsis
  • To create effective biosensor platforms, specific ligands with functional handles are essential for proper immobilization on sensor surfaces.
  • A library of papain inhibitors featuring various azide linkers was developed, utilizing copper-free strain-promoted azide-alkyne cycloaddition (SPAAC) for immobilization.
  • Molecular docking studies revealed that while the azide group is small, its incorporation can significantly impact binding affinity; a suitable linker position was identified to maintain affinity.
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Article Synopsis
  • Enzymatic peptide synthesis is gaining attention as a cost-effective alternative to traditional chemical methods, but existing strategies often rely on expensive and unstable guanidinophenyl ester (OGp) groups.
  • Researchers are exploring simpler ester groups, specifically Z-Gly-Act, to replace OGp for more accessible enzyme-specific activation in peptide bond formation.
  • Promising results were achieved using benzyl (OBn) and dimethylaminophenyl (ODmap) esters, which were tested in the synthesis of biologically active dipeptides and analyzed through computational docking to understand their reactivities.
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Article Synopsis
  • The substrate mimetics approach allows for small-scale enzymatic peptide-bond synthesis in water by using an ester leaving group to enhance enzyme recognition of different amino acids and peptides.
  • The guanidinophenyl group (OGp) has been successfully applied with papain, expanding its use beyond other serine proteases like trypsin and chymotrypsin.
  • Computational docking studies reveal a unique activation mechanism for OGp esters in papain, and molecular dynamics simulations help identify the effectiveness of various amino acid donors for synthesizing dipeptides.
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