Search results for "405"

Translocation of enzymes into a mesoporous MOF for enhanced catalytic activity under extreme conditions

2019

Translocation of protease into mesoporous MIL-101-NH2 results in enhanced catalytic activity, excellent recyclability and tolerance to competing enzymes.

Fluorogenic Enzyme-Triggered Domino Reactions Producing Quinoxalin-2(1H)-one-based Heterocycles

2020

International audience; A simple and effective biocompatible domino reaction triggered by a model protease and leading to formation of strongly fluorescent quinoxalin-2(1H)-one N-heterocycles is described. Some positive attributes including versatility and ability to provide outstanding fluorescence "OFF-ON" responses were revealed by this work. They open the way for practical applications of this novel type of "covalent-assembly" based fluorescent probes in the fields of sensing and bioimaging. Among the myriad of synthetic transformations and catalysts currently available for concise and efficient synthesis of organic molecules, bioinspired approaches based on the use of enzymes often int…

2020

The facile synthesis and detailed investigation of a class of highly potent protease inhibitors based on 1,4-naphthoquinones with a dipeptidic recognition motif (HN-l-Phe-l-Leu-OR) in the 2-position and an electron-withdrawing group (EWG) in the 3-position is presented. One of the compound representatives, namely the acid with EWG = CN and with R = H proved to be a highly potent rhodesain inhibitor with nanomolar affinity. The respective benzyl ester (R = Bn) was found to be hydrolyzed by the target enzyme itself yielding the free acid. Detailed kinetic and mass spectrometry studies revealed a reversible covalent binding mode. Theoretical calculations with different density functionals (DFT…

Magneto-structural versatility of copper(II)-3-phenylpropionate coordination polymers with N-donor coligands.

2015

A novel series of copper(II) coordination polymers [Cu2(O2CC8H9)4(pyz)]n (1), [Cu2(O2CC8H9)4(dps)]n (2), {[Cu(O2CC8H9)2(dps)(H2O)]·H2O}n (3), {[NaCu(O2CC8H9)2(bpm)(NO3)]·H2O}n (4), and [Cu4(O2CC8H9)6(OH)2(bpp)2]n (5) [O2CC8H9− = 3-phenylpropionate anion, pyz = pyrazine, dps = di(4-pyridyl)sulfide, bpm = 2,2′-bipyrimidine, and bpp = 1,3-bis(4-pyridyl)propane] have been synthesized and magneto-structurally investigated. Compounds 1 and 2 belong to a large group of copper(II) carboxylates where bis-monodentate pyz (1) and dps (2) ligands connect the paddle-wheel [CuII2(μ-O2CC8H9)4] units leading to alternating copper(II) chains. The structure of 3 consists of uniform chains of trans-[CuII(O2CC…

Bistetrazine-Cyanines as Double-Clicking Fluorogenic Two-Point Binder or Crosslinker Probes

2018

Fluorogenic probes can be used to minimize the background fluorescence of unreacted and nonspecifically adsorbed reagents. The preceding years have brought substantial developments in the design and synthesis of bioorthogonally applicable fluorogenic systems mainly based on the quenching effects of azide and tetrazine moieties. The modulation power exerted by these bioorthogonal motifs typically becomes less efficient on more conjugated systems; that is, on probes with redshifted emission wavelength. To reach efficient quenching, that is, fluorogenicity, even in the red range of the spectrum, we present the synthesis, fluorogenic, and conjugation characterization of bistetrazine-cyanine pro…

Chiral synthetic pseudopeptidic derivatives as triplet excited state quenchers

2009

The behavior of 6 pseudopeptidic models, synthesized by connecting different protected amino acids (Trp, Tyr, Phe, and Lys) with various diamino spacers, as quenchers of the triplet excited state of tiaprofenic acid (and its methyl ester), has been investigated. A series of quenching constants have been determined, which depend on the nature of the quencher and on the stereochemistry of the excited drug. A significant degree of stereodifferentiation has been found for the peptidomimetic synthesized with Phe and Tyr linked by a piperazine bridge. The obtained results support the utility of laser flash photolysis (LFP) as a tool to investigate the interactions between photoexcited drugs and s…

Near Isotropic D4d Spin Qubits as Nodes of a Gd(III)-Based Metal-Organic Framework

2021

Embedding coherent spin motifs in reproducible molecular building blocks is a promising pathway for the realization of quantum technologies. Three-dimensional (3D) MOFs are a versatile platform for the rational design of extended structures employing coordination chemistry. Here, we report the synthesis and characterization of a gadolinium(III)-based MOF, [Gd(bipyNO)4](TfO)3·xMeOH (bipyNO = bipyridine,N,N′-dioxide; TfO = triflate; and MeOH = methanol) (quMOF-1), which presents a unique coordination geometry that leads to a tiny magnetic anisotropy (in terms of D, an equivalent zero-field splitting would be achieved by D = 0.006 cm–1) even compared with regular Gd(III) complexes. Pulsed elec…

On the Nature of the Enzyme–Substrate Complex and the Reaction Mechanism in Human Arginase I. A Combined Molecular Dynamics and QM/MM Study

2020

We present here a detailed theoretical analysis of L-arginine hydrolysis catalyzed by Human Arginase I (HARGI). Our study combines classical molecular dynamic simulations of different model for the...

Electrosynthesis as a powerful method for the generation of catalytic intermediates: efficient isolation of a palladium aryl halide oxidative additio…

2011

International audience; Polyphosphane ligands of controlled conformation promote highly efficient palladium-catalyzed cross-coupling reactions. Electrosynthesis has been used as a new straightforward method to obtain important intermediates in the search for a better mechanistic understanding. As a proof of concept, the facile synthesis of a phenyl iodopalladium(II) complex (2) was conducted at the electrolysis scale from a readily electrogenerated unstable Pd0 precursor.

Molecular hydrogen (H 2 ) as a potential treatment for acute and chronic fatigue

2020

Many diseases as well as acute conditions can lead to fatigue, which can be either temporary or chronic in nature. Acute fatigue develops frequently after physical exercise or after alcohol hangover, whereas microbial infections such as influenza or COVID-19 and chronic diseases like Parkinson's disease or multiple sclerosis are often associated with chronic fatigue. Oxidative stress and a resulting disturbance of mitochondrial function are likely to be common denominators for many forms of fatigue, and antioxidant treatments have been shown to be effective in alleviating the symptoms of fatigue. In this study, we review the role of reactive oxygen and nitrogen species in fatigue and the an…