Using single molecule fluorescence resonance energy transfer, we investigated the interaction between a quadruplex-binding ligand and the human telomeric G-quadruplex. The binding of ...quinolinecarboxamide macrocycle to telomeric DNA was essentially irreversible and selectively induced and favored one quadruplex conformation. The ligand−quadruplex complex displayed intramolecular dynamics including quadruplex folding and unfolding in the absence of ligand association and dissociation. We report that the G-quadruplex can be stabilized without preventing the intrinsic intramolecular dynamics of telomeric DNA.
Synthetic helical aromatic amide foldamers and in particular those based on quinolines have recently attracted much interest due to their capacity to adopt bioinspired folded conformations that are ...highly stable and predictable. Additionally, the introduction of water-solubilizing side chains has allowed to evidence promising biological activities. It has also created the need for methods that may allow the parallel synthesis and screening of oligomers. Here, we describe the application of solid phase synthesis to speed up oligomer preparation and allow the introduction of various side chains. The synthesis of quinoline-based monomers bearing protected side chains is described along with conditions for activation, coupling, and deprotection on solid phase, followed by resin cleavage, side-chain deprotection, and HPLC purification. Oligomers having up to 8 units were thus synthesized. We found that solid phase synthesis is notably improved upon reducing resin loading and by applying microwave irradiation. We also demonstrate that the introduction of monomers bearing benzylic amines such as 6-aminomethyl-2-pyridinecarboxylic acid within the sequences of oligoquinolines make it possible to achieve couplings using a standard peptide coupling agent and constitute an interesting alternative to the use of acid chloride activation required by quinoline residues. The synthesis of a tetradecameric sequence was thus smoothly carried out. NMR solution structural studies show that these alternate aminomethyl-pyridine residues do not perturb the canonical helix folding of quinoline monomers in protic solvents, contrary to what was previously observed in nonprotic solvents.
Helically folded aromatic foldamers may constitute suitable candidates for the ab initio design of ligands for protein surfaces. As preliminary steps toward the exploration of this hypothesis, a ...tethering approach was developed to detect interactions between a protein and a foldamer by confining the former at the surface of the latter. Cysteine mutants of two therapeutically relevant enzymes, CypA and IL4, were produced. Two series of ten foldamers were synthesized bearing different proteinogenic side chains and either a long or a short linker functionalized with an activated disulfide. Disulfide exchange between the mutated cysteines and the activated disulfides yielded 20 foldamer-IL4 and 20 foldamer-CypA adducts. Effectiveness of the reaction was demonstrated by LC-MS, by MS analysis after proteolytic digestion, and by 2D NMR. Circular dichroism then revealed diastereoselective interactions between the proteins and the foldamers confined at their surface which resulted in a preferred handedness of the foldamer helix. Helix sense bias occurred sometimes with both the short and the long linkers and sometimes with only one of them. In a few cases, helix handedness preference is found to be close to quantitative. These cases constitute valid candidates for structural elucidation of the interactions involved.
The urine biomarkers tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7) have been validated for predicting and stratifying AKI. In this study, ...we analyzed the utility of these biomarkers for distinguishing between transient and persistent AKI in the early phase of septic shock.
We performed a prospective, multicenter study in 11 French ICUs. Patients presenting septic shock, with the development of AKI within the first 6 h, were included. Urine TIMP-2*IGFBP7 was determined at inclusion (0 h), 6 h, 12 h, and 24 h. AKI was considered transient if it resolved within 3 days. Discriminative power was evaluated by receiver operating characteristic (ROC) curve analysis.
We included 184 patients, within a median IQR time of 1.0 0.0-3.0 h after norepinephrine (NE) initiation; 100 (54%) patients presented transient and 84 (46%) presented persistent AKI. Median IQR baseline urine TIMP-2*IGFBP7 was higher in the persistent AKI group (2.21 0.81-4.90 (ng/ml)
/1000) than in the transient AKI group (0.75 0.20-2.12 (ng/ml)
/1000; p < 0.001). Baseline urine TIMP-2*IGFBP7 was poorly discriminant, with an AUROC 95% CI of 0.67 0.59-0.73. The clinical prediction model combining baseline serum creatinine concentration, baseline urine output, baseline NE dose, and baseline extrarenal SOFA performed well for the prediction of persistent AKI, with an AUROC 95% CI of 0.81 0.74-0.86. The addition of urine TIMP-2*IGFBP7 to this model did not improve the predictive performance.
Urine TIMP-2*IGFBP7 measurements in the early phase of septic shock discriminate poorly between transient and persistent AKI and do not improve clinical prediction over that achieved with the usual variables.
NCT02812784.
A planar trimeric macrocyclic oligoamide of 8-amino-2-quinoline carboxylic acid, bearing ammonium side chains, stabilizes the human telomeric G-quadruplex more strongly than the potent ligand ...telomestatin. Furthermore, a helical oligoamide tetramer also binds strongly to G-quadruplexes and is a new structural class of quadruplex ligand that appears to interact enantioselectively.
Older age is associated with worse outcome after out-of-hospital cardiac arrest (OHCA). Therefore, we tested the performance of CAHP score, to predict neurological outcome in elderly OHCA patients ...and to select patients most likely to benefit from coronary angiogram (CAG).
The present study was a retrospective multicentre observational study at 3 non-university hospitals and 1 university hospital. CAHP score was calculated, and its performance to predict outcomes was evaluated. Factors associated with the use of CAG were analysed and the rate of CAG across each CAHP score risk group reported.
One hundred seventy-six patients fulfilled inclusion criteria (median age of 81, 79–84), among which a cardiac cause was presumed for 99 patients. The hospital unfavourable outcome was 91%. The ROC-AUC values for hospital neurological outcome prediction of CAHP score was 0.81 0.68–0.94, showing good discrimination performance. ST-segment elevation in ECG and initial shockable rhythm were independent factors for performing early CAG, whereas age and distance from the percutaneous coronary intervention centre were independently associated with the absence of early CAG. The percentages of patients receiving early CAG in the low, medium and high CAHP score risk groups were 64%, 33% and 34%, respectively, and differed significantly between low CAHP score risk group and other groups (p = 0.02).
The CAHP score exhibited a good discrimination performance to predict neurological outcome in elderly OHCA patients. This score could represent a helpful tool for treatment allocation. A simple prognostication score could permit avoiding unnecessary procedures in patients with minimal chances of survival.
Finest selection: Side‐chain selective, end‐group selective, diastereoselective, and RNA‐ vs. DNA‐selective interactions have been revealed between multiturn helical aromatic amide foldamers having ...cationic side chains and G‐quadruplex aptamers.
Hybrid oligomeric sequences derived from both aliphatic and aromatic units are shown to adopt a folded conformation with an unprecedented architecture. Specifically, a δ-amino acid bearing an ...aliphatic amine6-aminomethyl-2-pyridinecarboxylic (P)was designed and synthesized as a flexible analogue of 6-amino-2-quinolinecarboxylic acid (Q). Oligomers P n (n = 2, 4, 8) were first synthesized but show no sign of folding in solution in organic solvents, unlike the Q n oligomers from which they are derived, which adopt particularly stable helical conformations. Hybrid oligomers (PQ) n (n = 1, 2, 4) were also prepared and were shown to adopt a novel folded conformation in the solid state where PQ units arrange into two stacks at a 90° angle from each other. Comprehensive NMR studies demonstrate that in solution this peculiar organization coexists with a helical conformation resembling that of Q n oligomers.
We previously identified quinoline‐based oligoamide helical foldamers and a trimeric macrocycle as selective ligands of DNA quadruplexes. Their helical structures might permit targeting of the ...backbone loops and grooves of G‐quadruplexes instead of the G‐tetrads. Given the vast array of morphologies G‐quadruplex structures can adopt, this might be a way to achieve sequence selective binding. Here, we describe the design and synthesis of molecules based on macrocyclic and helically folded oligoamides. We tested their ability to interact with the human telomeric G‐quadruplex and an array of promoter G‐quadruplexes by using FRET melting assay and single‐molecule FRET. Our results show that they constitute very potent ligands—comparable to the best so far reported. Their modes of interaction differ from those of traditional tetrad binders, thus opening avenues for the development of molecules specific for certain G‐quadruplex conformations.
Helical foldamer ligands were shown by FRET melting and single‐molecule FRET to have high binding potency to the human telomeric G‐quadruplex and an array of promoter G‐quadruplexes. Their modes of interaction differ from those of traditional G‐tetrad binders, thus opening avenues for further developments towards selective ligands for certain G‐quadruplex conformations.
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