Michael-type addition (conjugate addition reaction between electron-poor olefins and nucleophiles, such as thiols) has been successfully used as a convenient tool for surface functionalization. Due to its mild character, this method is potentially useful for the introduction of sensitive groups, which can provide bioactivity and targeting possibilities to surfaces of, for example, colloidal carriers. As reaction partners, in our study we have used thiols, possibly present in peptidic structures, and acrylates, at the end of protein-repellant PEG chains. Satisfactory results were obtained with thiols in solution and acrylic groups bound to the surface. Alternatively, the use of thiols on the particles, even if generated in situ, did not provide useful results.
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http://dx.doi.org/10.1021/bc0340621 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
Humboldt-Universität zu Berlin, Department of Chemistry, Laboratory of Organic Chemistry and Functional Materials, Brook-Taylor-Str. 2, 12489, Berlin, GERMANY.
Here we disclose that spiropyrans are able to undergo dynamic covalent exchange via their corresponding merocyanine isomers. In the latter, the indolinium moieties can be exchanged by a Michael-type addition-elimination sequence, in which a methylene indoline attacks a merocyanine and subsequently the initial indoline fragment is cleaved. The rate and position of the exchange equilibrium strongly depend on the reaction conditions as well as the substitution pattern on the methylene indoline fragments.
View Article and Find Full Text PDFACS Catal
December 2024
Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States.
Lanthipeptides are ribosomally synthesized and post-translationally modified peptides (RiPPs) characterized by the presence of thioether cross-links called lanthionine and methyllanthionine, formed by dehydration of Ser/Thr residues and Michael-type addition of Cys side chains onto the resulting dehydroamino acids. Class II lanthipeptide synthetases are bifunctional enzymes responsible for both steps, thus generating macrocyclic natural products. ProcM is part of a group of class II lanthipeptide synthetases that are known for their remarkable substrate tolerance, having large numbers of natural substrates with highly diverse peptide sequences.
View Article and Find Full Text PDFMolecules
November 2024
Departamento de Síntesis Orgánica, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia 58030, Mexico.
The use of deep eutectic solvents (DESs) as catalysts presents indisputable advantages, for example, their simplicity of preparation, high biodegradability, and recyclability, as well as zero toxicity and their effectiveness as environmentally friendly reaction media. However, aspects related to their reactivity and catalytic activity are still unclear. In this work, we explore the versatility of ChCl/ZnCl DES in the formation of C-C bonds through the Michael-type addition of pyrrole to maleimide, where ChCl/ZnCl DES leads to catalysis and chelation of the substrates, thus describing a recommended method for the construction of C-C bonds with high atomic economy.
View Article and Find Full Text PDFAdv Sci (Weinh)
November 2024
School of Chemistry and Chemical Engineering, Zhejiang Sci-Tech University, Hangzhou, 310018, China.
Chiral fully-substituted allenes are synthetically significant and pivotal building blocks that can engage in diverse transformations toward a variety of bioactive molecules. The enantioselective assembly of these skeletons using readily available reactants offers significant advantages but remains challenging. Herein, an asymmetric formal Michael-type addition of alkynyl imines with the key alkylgold intermediates derived in situ from N-propargylamides is accomplished under gold-complex and chiral quinine-derived squaramide (QN-SQA) synergetic catalysis.
View Article and Find Full Text PDFJ Mater Chem B
November 2024
Department of Chemistry, Centre for Advanced Studies, Guru Nanak Dev University, Amritsar, Punjab, India.
Endogenous release of HSO during the enzymatic oxidation of sulfur containing amino acids in mitochondria or insufficiency of sulfite oxidase results in the accumulation of sulfite and thiosulfate in biological fluids affecting mitochondrial homeostasis of brain mitochondria associated with serious clinical symptoms related to neurological disorders. The red fluorescent probe MGQ undergoes self-assembly in water and reveals aggregation induced quenching of fluorescence. MGQ reveals 143-fold and 179-fold increases in fluorescence intensity at 645 nm, respectively, in the presence of HSA and BSA and does not significantly differentiate between two albumins.
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