- Kinetically Controlled Lifetimes in Redox-Responsive Transient Supramolecular Hydrogels
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It remains challenging to program soft materials to show dynamic, tunable time-dependent properties. In this work, we report a strategy to design transient supramolecular hydrogels based on kinetic control of competing reactions. Specifically, the pH-triggered self-assembly of a redox-active supramolecular gelator, N,N′-dibenzoyl-l-cystine (DBC) in the presence of a reducing agent, which acts to disassemble the system. The lifetimes of the transient hydrogels can be tuned simply by pH or reducing agent concentration. We find through kinetic analysis that gel formation hinders the ability of the reducing agent and enables longer transient hydrogel lifetimes than would be predicted. The transient hydrogels undergo clean cycles, with no kinetically trapped aggregates observed. As a result, multiple transient hydrogel cycles are demonstrated and can be predicted. This work contributes to our understanding of designing transient assemblies with tunable temporal control.
- Wojciechowski, Jonathan P.,Martin, Adam D.,Thordarson, Pall
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- Comparative reactivity analysis of small-molecule thiol surrogates
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Targeted covalent inhibitors represent an increasingly popular approach to modulate challenging drug targets. Since covalent and non-covalent interactions are both contributing to the affinity of these compounds, evaluation of their reactivity is a key-step to find feasible warheads. There are well-established HPLC- and NMR-based kinetic assays to tackle this task, however, they use a variety of cysteine-surrogates including cysteamine, cysteine or acetyl-cysteine and GSH. The diverse nature of the thiol sources often makes the results incomparable that prevents compiling a comprehensive knowledge base for the design of covalent inhibitors. To evaluate kinetic measurements from different sources we performed a comparative analysis of the different thiol surrogates against a designed set of electrophilic fragments equipped with a range of warheads. Our study included seven different thiol models and 13 warheads resulting in a reactivity matrix analysed thoroughly. We found that the reactivity profile might be significantly different for various thiol models. Comparing the different warheads, we concluded that – in addition to its human relevance - glutathione (GSH) provided the best estimate of reactivity with highest number of true positives identified.
- ábrányi-Balogh, Péter,Imre, Tímea,Keser?, Gy?rgy Miklós,Petri, László,Varga, Petra Regina
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- A "catch-and-release" protocol for alkyne-tagged molecules based on a resin-bound cobalt complex for peptide enrichment in aqueous media
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The development of new and mild protocols for the specific enrichment of biomolecules is of significant interest from the perspective of chemical biology. A cobalt-phosphine complex immobilised on a solid-phase resin has been found to selectively bind to a propargyl carbamate tag, that is, "catch", under dilute aqueous conditions (pH 7) at 4-°C. Upon acidic treatment of the resulting resin-bound alkyne-cobalt complex, the Nicholas reaction was induced to "release" the alkyne-tagged molecule from the resin as a free amine. Model studies revealed that selective enrichment of the alkyne-tagged molecule could be achieved with high efficiency at 4-°C. The proof-of-concept was applied to an alkyne-tagged amino acid and dipeptide. Studies using an alkyne-tagged dipeptide proved that this protocol is compatible with various amino acids bearing a range of functionalities in the side-chain. In addition, selective enrichment and detection of an amine derived from the "catch and release" of an alkyne-tagged dipeptide in the presence of various peptides has been accomplished under highly dilute conditions, as determined by mass spectrometry. Catch and release: The specific enrichment of alkyne-tagged molecules has been achieved by using cobalt beads. A cobalt complex bound to a resin was found to selectively "catch" a propargyl carbamate tag under dilute aqueous conditions (see scheme). Upon acidic treatment of the alkyne-cobalt complex, the Nicholas reaction was induced to "release" an amine. Studies using an alkyne-tagged dipeptide proved its compatibility with various amino acids and peptides under highly dilute conditions.
- Miyazaki, Ayako,Asanuma, Miwako,Dodo, Kosuke,Egami, Hiromichi,Sodeoka, Mikiko
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supporting information
p. 8116 - 8128
(2014/07/07)
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- Medium buffer effects on the condensation of l -cysteine and aryl nitriles to (R)-2-Aryl-4,5-dihydrothiazole-4-carboxylic acids
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The condensation of l-cysteine and aryl nitriles to (R)-2-aryl-4,5- dihydrothiazole-4-carboxylic acids in buffered media was reinvestigated. Pure products (yields of 58-95%; up to 99% ee) were obtained in a NaHCO 3/NaOH-buffered aqueous alcoholic medium. Georg Thieme Verlag Stuttgart New York.
- Maltsev, Oleg V.,Walter, Valerianne,Brandl, Matthias J.,Hintermann, Lukas
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p. 2763 - 2767
(2013/10/21)
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- Cysteine-activated hydrogen sulfide (H2S) donors
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H2S, the newly discovered gasotransmitter, plays important roles in biological systems. However, the research on H2S has been hindered by the lack of controllable H2S donors that could mimic the slow and continuous H2S generation process in vivo. Herein we report a series of cysteine-activated H2S donors. Structural modifications of these molecules can regulate the rates of H2S generation. These compounds can be useful tools in H2S research.
- Zhao, Yu,Wang, Hua,Xian, Ming
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supporting information; experimental part
p. 15 - 17
(2011/03/17)
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- NOVEL ANTIOXIDANTS AND METHODS OF TREATMENT
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Formula 1 is an antioxidant compound, wherein R, R1, or D is an antioxidant substituent; R and D are each independently selected from hydrogen or groups containing cysteine, thiols, disulfides, amino acids, amines, amides, or carboxylic acids; when one of
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Page/Page column 23; 25
(2009/12/28)
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- Selective synthesis and structural elucidation of S-acyl- and N-acylcysteines
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(Chemical Equation Presented) N-(Acyl)-1H-benzotriazoles 6a-f react with L-cysteine 5 at 20°C to give exclusively (i) N-acyl-L-cysteines 8a-e in the presence of triethylamine in CH3CN-H2O (3:1), but (ii) S-acyl-L-cysteines 7a-e in CH
- Katritzky, Alan R.,Tala, Srinivasa R.,Abo-Dya, Nader E.,Gyanda, Kapil,El-Gendy, Bahaa El-Dien M.,Abdel-Samii, Zakaria K.,Steel, Peter J.
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experimental part
p. 7165 - 7167
(2009/12/09)
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- Dynamic combinatorial mass spectrometry leads to metallo-β-lactamase inhibitors
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The use of protein ESI mass spectrometry under non-denaturing conditions to analyze a dynamic combinatorial library of thiols/disulfides with the BcII metallo-β-lactamase enabled the rapid identification of an inhibitor with a Ki of 1 μM. The study exemplifies the utility of protein-MS for screening dynamic mixtures of potential enzyme-inhibitors.
- Liénard, Beno?t M. R.,Hüting, Rebekka,Lassaux, Patricia,Galleni, Moreno,Frère, Jean-Marie,Schofield, Christopher J.
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p. 684 - 688
(2008/09/18)
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- Beauveria bassiana ATCC 7159 contains an L-specific α-amino acid benzamidase
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Biotransformation of a series of racemic N-benzoyl α-amino acids by the fungus Beauveria bassiana ATCC 7159 results in isolation of the corresponding D-amino acid benzamides in high enantiomeric purity and yield.
- Holland, Herbert L.,Andreana, Peter R.,Salehzadeh-Asl, Reza,Van Vliet, Aaron,Ihasz, Nancy J.,Brown, Frances M.
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p. 667 - 672
(2007/10/03)
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