Isovaleryl coenzyme A (IV-CoA) is an important precursor for iso-fatty acids and lipids. It acts in the development of myxobacteria, which can produce this compound from acetyl-CoA through alternative IV-CoA biosynthesis (aib). A central reaction of aib is catalyzed by AibA/AibB, which acts as a cofactor-free decarboxylase despite belonging to the family of CoA-transferases. We developed an efficient expression system for AibA/AibB that allowed the determination of high-resolution crystal structures in complex with different ligands. Through mutational studies, we show that an active-site cysteine previously proposed to be involved in decarboxylation is not required for activity. Instead, AibA/AibB seems to induce an intramolecular decarboxylation by binding its substrate in a hydrophobic cavity and forcing it into a bent conformation. Our study opens opportunities for synthetic biology studies, since AibA/AibB may be suitable for the production of isobutene, a precursor of biofuels and chemicals.
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http://dx.doi.org/10.1002/anie.201701992 | DOI Listing |
J Phys Chem A
December 2024
Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom.
Photoelectron imaging of the doubly deprotonated ethylenediaminetetraacetic acid dianion (EDTA) at variable wavelengths indicates two electron loss pathways: direct detachment and thermionic emission from monoanions. The structure of EDTA is also investigated by electronic structure calculations, which indicate that EDTA has two intramolecular hydrogen bonds linking a carboxylate and carboxylic acid group at either end of the molecular backbone. The direct detachment feature in the photoelectron spectrum is very broad and provides evidence for a dissociative photodetachment, where decarboxylation occurs rapidly after electron loss.
View Article and Find Full Text PDFOrg Lett
December 2024
Institute of Green Chemistry and Molecular Engineering, GBRCE for Functional Molecular Engineering, Lehn Institute of Functional Materials, School of Chemistry, Sun Yat-sen University, Guangzhou 510006, PR China.
Radical Smiles rearrangements have emerged as powerful methodologies for constructing carbon-carbon bonds through intramolecular radical addition and fragmentation under milder conditions, with SO released as a byproduct. However, SO-retaining Smiles rearrangements, which can yield valuable alkyl sulfone derivatives, have been scarcely explored. In this study, we present an unprecedented iron-catalyzed SO-retaining Smiles rearrangement initiated by the decarboxylation of aliphatic carboxylic acids.
View Article and Find Full Text PDFOrg Lett
October 2024
Department of Analytical & Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India.
Here we report the development of unprecedented silver-catalyzed intramolecular annulations of -acrolyl-2-(3-indolyl) benzimidazoles with alkyl carboxylic acids to construct complex fused-pentacyclic alkaloid scaffolds. Divergent reactivities are noticed with altered groups at C2-indole of the substrate. The reaction proceeds through decarboxylative alkylation, followed by dearomative annulation in a domino manner with excellent diastereoselectivity.
View Article and Find Full Text PDFOrg Biomol Chem
November 2024
State Key Laboratory and Institute of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, PR China.
A concise synthesis of (-)-quinocarcinol methyl ester was accomplished with an overall yield of 39% through a 9-step longest linear sequence (LLS). Our synthesis features a two-step ester reduction/reductive amination sequence, a stereoselective [3 + 2] intramolecular cross-cycloaddition for the construction of bicyclo[3.2.
View Article and Find Full Text PDFJ Phys Chem Lett
September 2024
Department of Chemistry, Kyungpook National University, Daegu 41566, South Korea.
Multistate nonadiabatic dynamics combined with Mixed-Reference Spin-Flip Time-Dependent Density Functional Theory (MRSF-TDDFT) were performed to investigate the chemoexcitation dynamics of firefly dioxetanone (FDO in S) to oxyluciferin (OxyLH in S) and its subsequent decay dynamics. The formation of oxyluciferin occurs within approximately 100 fs and is primarily controlled by oscillatory CO decarboxylation. Unexpected radiationless decay from oxyluciferin was also observed, facilitated by intramolecular rotation.
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