Efficient consecutive 1,2,3-triazole formations using multiazide platforms are disclosed. On the basis of unique clickability of the 1-adamantyl azido group, a four-step synthesis of tetrakis(triazole)s was achieved from a tetraazide platform molecule. This method was applied to a convergent synthesis of tetrafunctionalized probes in a modular synthetic manner.
A protection method for cycloalkynes by the formation of (hexafluoroacetylacetonato)copper(i)-cycloalkyne complexes is disclosed. Various complexes having functional groups were efficiently prepared, which are easily purified by silica-gel column chromatography. Selective click reactions were realized through the complexation of cycloalkynes with copper.
The endoplasmic reticulum (ER) is responsible for folding secretory and membrane proteins, but disturbed ER proteostasis may lead to protein aggregation and subsequent cellular and clinical pathologies. Chemical chaperones have recently emerged as a potential therapeutic approach for ER stress-related diseases. Here, we identified 2-phenylimidazo[2,1-b]benzothiazole derivatives (IBTs) as chemical chaperones in a cell-based high-throughput screen. Biochemical and chemical biology approaches revealed that IBT21 directly binds to unfolded or misfolded proteins and inhibits protein aggregation. Finally, IBT21 prevented cell death caused by chemically induced ER stress and by a proteotoxin, an aggression-prone prion protein. Taken together, our data show the promise of IBTs as potent chemical chaperones that can ameliorate diseases resulting from protein aggregation under ER stress.
Benzothiazoles/pharmacology , Endoplasmic Reticulum/drug effects , High-Throughput Screening Assays/methods , Protein Aggregation, Pathological/prevention & control , Benzothiazoles/chemistry , Endoplasmic Reticulum/metabolism , Endoplasmic Reticulum Stress/drug effects , HEK293 Cells , Humans , Prion Proteins/metabolism , Proteostasis/drug effects , Unfolded Protein Response/drug effects
A facile method for preparing various functional cycloalkynes, including proteins incorporated with a cycloalkyne moiety, from the corresponding azides is developed. Treatment of diynes bearing strained and terminal alkyne moieties with a copper salt enabled terminal alkyne-selective click conjugation with azides, whereas a more azidophilic strained alkyne moiety was transiently protected from the click reaction via complexation with copper.
Alkynes/chemistry , Azides/chemistry , Click Chemistry/methods , Fluorescent Dyes/chemistry , Proteins/chemistry , Alkynes/chemical synthesis , Azides/chemical synthesis , Catalysis , Copper/chemistry , Cyclization , Cycloaddition Reaction/methods , Fluorescent Dyes/chemical synthesis , HEK293 Cells , Humans , Optical Imaging , Proteins/analysis , Proteins/chemical synthesis
Prostaglandin E receptor EP4, a G-protein-coupled receptor, is involved in disorders such as cancer and autoimmune disease. Here, we report the crystal structure of human EP4 in complex with its antagonist ONO-AE3-208 and an inhibitory antibody at 3.2 Å resolution. The structure reveals that the extracellular surface is occluded by the extracellular loops and that the antagonist lies at the interface with the lipid bilayer, proximal to the highly conserved Arg316 residue in the seventh transmembrane domain. Functional and docking studies demonstrate that the natural agonist PGE2 binds in a similar manner. This structural information also provides insight into the ligand entry pathway from the membrane bilayer to the EP4 binding pocket. Furthermore, the structure reveals that the antibody allosterically affects the ligand binding of EP4. These results should facilitate the design of new therapeutic drugs targeting both orthosteric and allosteric sites in this receptor family.
Receptors, Prostaglandin E, EP4 Subtype/chemistry , Receptors, Prostaglandin E, EP4 Subtype/metabolism , Allosteric Regulation , Animals , Antibodies, Monoclonal/chemistry , Antibodies, Monoclonal/metabolism , Binding Sites , Caprylates/chemistry , Caprylates/metabolism , Crystallography, X-Ray , Epoprostenol/analogs & derivatives , Epoprostenol/chemistry , Epoprostenol/metabolism , Humans , Ligands , Lipid Bilayers , Molecular Docking Simulation , Naphthalenes/chemistry , Naphthalenes/metabolism , Phenyl Ethers/chemistry , Phenyl Ethers/metabolism , Phenylbutyrates/chemistry , Phenylbutyrates/metabolism , Receptors, Prostaglandin E, EP4 Subtype/antagonists & inhibitors , Receptors, Prostaglandin E, EP4 Subtype/genetics , Spodoptera/genetics
Various 2,3-disubstituted 6,7-thienobenzynes have been efficiently generated from the corresponding o-silylaryl triflate-type precursors by activation with fluoride ions. The method has expanded the scope of synthesizable multisubstituted benzothiophenes, including those with various heteroatom substituents, and can be applied to the synthesis of EP4 antagonist analogs.
