3° SEMINARIO QUÍMICA ORGÁNICA IQUIR 2023

SEMINARIO QUÍMICA ORGÁNICA 17-04-23

EXPOSITOR: Dra. Agustina La Venia

TÍTULO: "Tetrazine evolution in bioorthognal IEDDA reactions".

FUENTE: 

J. Am. Chem. Soc. 2022, 144, 1647
Chem. Soc. Rev. 2017, 46, 4895
Molecules 2021, 26, 1868

DÍA, HORA y LUGAR: Lunes 17 de abril de 2023, 12:50 h, Aula 1 y virtual

Modalidad virtual, Link: meet.google.com/hjn-ygro-twf (Plataforma MEET GOOGLE)

RESUMEN: The emerging inverse electron demand Diels–Alder (IEDDA) reaction stands out from other bioorthogonal reactions by virtue of its unmatchable kinetics, excellent orthogonality and biocompatibility. With the recent discovery of novel dienophiles and optimal tetrazine coupling partners, attention has now been turned to the use of IEDDA approaches in basic biology, imaging and therapeutics. An example of spatiotemporally controlled labeling and patterning of biomolecules in live cells through the catalytic activation of bioorthogonal chemistry with light, referred to as “CABL”, is described. An unreactive dihydrotetrazine (DHTz) is photocatalytically oxidized in the intracellular environment by ambient O2 to produce a tetrazine that immediately reacts with atrans-cyclooctene (TCO) dienophile. 6-(2-Pyridyl)- dihydrotetrazine-3-carboxamides were developed as stable, cell permeable DHTz reagents that upon oxidation produce the most reactive tetrazines ever used in live cells with Diels−Alder kinetics exceeding k2 of 106 M−1 s−1. CABL photocatalysts are based on fluorescein or silarhodamine dyes with activation at 470 or 660 nm. Strategies for limiting extracellular production of singlet oxygen are described that increase the cytocompatibility of photocatalysis. The HaloTag self-labeling platform was used to introduce DHTz tags

to proteins localized in the nucleus, mitochondria, actin, or cytoplasm, and high-yielding subcellular activation and labeling with a TCO-fluorophore were demonstrated. CABL is light-dose dependent, and two-photon excitation promotes CABL at the suborganelle level to selectively pattern live cells under no-wash conditions. CABL was also applied to spatially resolved live-cell labeling of an endogenous protein target by using TIRF microscopy to selectively activate intracellular monoacylglycerol lipase tagged with DHTz-labeled small molecule covalent inhibitor. Beyond spatiotemporally controlled labeling, CABL also improves the efficiency of “ordinary” tetrazine ligations by rescuing the reactivity of commonly used 3-aryl-6-methyltetrazine reporters that become partially reduced to DHTzs inside cells.