Stilbene synthase (STS) and chalcone synthase (CHS) each catalyze the formation of a tetraketide intermediate from a CoA-tethered phenylpropanoid starter and three molecules of malonyl-CoA, but use different cyclization mechanisms to produce distinct chemical scaffolds for a variety of plant natural products. Here we present the first STS crystal structure and identify, by mutagenic conversion of alfalfa CHS into a functional stilbene synthase, the structural basis for the evolution of STS cyclization specificity in type III polyketide synthase (PKS) enzymes. Additional mutagenesis and enzymatic characterization confirms that electronic effects rather than steric factors balance competing cyclization specificities in CHS and STS. Finally, we discuss the problematic in vitro reconstitution of plant stilbenecarboxylate pathways, using insights from existing biomimetic polyketide cyclization studies to generate a novel mechanistic hypothesis to explain stilbenecarboxylate biosynthesis.
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http://dx.doi.org/10.1016/j.chembiol.2004.05.024 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
Chinese Academy of Sciences Fujian Institute of Research on the Structure of Matter, State Key Laboratory of Structural Chemistry, 350108, Fuzhou, CHINA.
Here, we report the facile synthesis of imidazole-linked porous organic cages (IPOCs) via an in-situ cyclization reaction protocol. Specifically, three IPOCs with [2+4] lantern-like structures and one with a [3+6] triangular prism structure were successfully prepared through condensation reactions between tetraformyl-functionalized calix[4]arene and bis(o-phenylenediamine) monomers in a single pot. Notably, these IPOCs exhibit high porosity, with Brunauer-Emmett-Teller (BET) specific surface areas reaching up to 1162 m2 g-1.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Chemistry, Northwestern University, Technological Institute, Evanston, Illinois 60208, United States.
Recent advances in redox flow batteries have made them a viable option for grid-scale energy storage, however they exhibit low energy density. One way to boost energy density is by increasing the cell potential using a nonaqueous system. Molecular engineering has proven to be an effective strategy to develop redox-active compounds with extreme potentials but these are usually challenged by resource sustainability of the newly developed redox materials.
View Article and Find Full Text PDFPharmaceuticals (Basel)
December 2024
Department of Chemistry, Faculty of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh 11623, Saudi Arabia.
Background: Recently, pyrido[2,3-] pyrimidine, triazolopyrimidine, thiazolopyrimidine, quinoline, and pyrazole derivatives have gained attention due to their diverse biological activities, including antimicrobial, antioxidant, antitubercular, antitumor, anti-inflammatory, and antiviral effects.
Objective: The synthesis of new heterocyclic compounds including 5-quinoline-pyrido[2,3-] pyrimidinone (-, , -), 6-quinoline-pyrido[2,3-]thiazolo[3,2-]pyrimidinone (, , -), 1,2,4-triazole-6-quinoline-pyrido[2,3-]thiazolo[3,2-]pyrimidinone (-), and pyrido[2,3-]thiazolo[3,2-]pyrimidine-ethyl-(pyridine)-9-thiaazabenzo[]azulenone () derivatives was performed with high yields while evaluating antimicrobial activities.
Methods: A new series of quinoline-pyrido[2,3-]thiazolo[3,2-]pyrimidine derivatives were prepared using a modern style and advanced technology, resulting in high yields of these new compounds.
Antibiotics (Basel)
December 2024
Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya 16/10, Moscow 117997, Russia.
Irumamycin (Iru) is a complex polyketide with pronounced antifungal activity produced by a type I polyketide (PKS) synthase. Iru features a unique hemiketal ring and an epoxide group, making its biosynthesis and the structural diversity of related compounds particularly intriguing. In this study, we performed a detailed analysis of the biosynthetic gene cluster (BGC) to uncover the mechanisms underlying Iru formation.
View Article and Find Full Text PDFACS Omega
December 2024
Department of Gastroenterology, Xiamen University Affiliated Chenggong Hospital, Xiamen City, Fujian Province 361003, China.
MicroRNAs (miRNAs), which play critical roles in regulating gene expression and cell functions, are recognized as potential biomarkers for various human diseases, including gastric ulcers. The reliable, specific, and sensitive detection of miRNA is highly recommended for the clinical diagnosis and therapy of different diseases. Herein, we depict a label-free and low-background fluorescent assay for the highly sensitive detection of miRNAs by coupling target miRNA-triggered cyclization of a padlock, circular padlock-mediated catalytic hairpin assembly (CHA), and primer exchange reaction (PER)-assisted signal generation.
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