Nickel salts catalyze fast cysteine arylation with 2-nitroarylboronic acids. The process uses cheap, readily-available reagents and allows introduction of diverse chemical handles.
Metal-based bioconjugation linkages represent a little-studied approach to protein functionalization that provides novel reactivity, stability, and function. Described is an organometallic bioconjugation, employing rhodium(III) salts, to link boronic acids with tyrosine residues by an arene complex. Both peptides and proteins are amenable to the mild bioconjugation in aqueous media, allowing incorporation of useful functionalities, such as affinity handles or fluorophores. Because of the metastability of the inorganic linkage, the conjugates are susceptible to cleavage by nucleophilic redox mediators but are stable toward typical biological conditions.
Plant-microbe interactions are mediated by signaling compounds that control vital plant functions, such as nodulation, defense, and allelopathy. While interruption of signaling is typically attributed to biological processes, potential abiotic controls remain less studied. Here, we show that higher organic carbon (OC) contents in soils repress flavonoid signals by up to 70%. Furthermore, the magnitude of repression is differentially dependent on the chemical structure of the signaling molecule, the availability of metal ions, and the source of the plant-derived OC. Up to 63% of the signaling repression occurs between dissolved OC and flavonoids rather than through flavonoid sorption to particulate OC. In plant experiments, OC interrupts the signaling between a legume and a nitrogen-fixing microbial symbiont, resulting in a 75% decrease in nodule formation. Our results suggest that soil OC decreases the lifetime of flavonoids underlying plant-microbe interactions.
Small and simple bioorthogonal reactive
handles that can be readily
encoded by natural processes are important for bioconjugation. A rapid
nickel-promoted N–H arylation of pyroglutamate–histidine
sequences with 2-nitroarylboronic acids proceeds under mild aqueous
conditions. Chemoselective activation of a lactam amide N–H
within a peptide or protein provides a new approach to selective conjugation
in polyamide structures.
Polypeptides present remarkable selectivity challenges for chemical methods. Amino groups are ubiquitous in polypeptide structure, yet few paradigms exist for reactivity and selectivity in arylation of amine groups. This communication...
Boronic acids can play diverse roles
when applied in biological
environments, and employing boronic acid structures in tandem could
provide new tools for multifunctional probes. This Letter describes
a pair of boronic acid functional groups, 2-nitro-arylboronic acid
(NAB) and (E)-alkenylboronic acid (EAB), that enable
sequential cross-coupling through stepwise nickel- and copper-catalyzed
processes. The selective coupling of NAB groups enables the preparation
of stapled peptides, protein–protein conjugates, and other
bioconjugates.
This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record.
Transition‐metal catalysis provides new approaches to selectivity and the activation of otherwise inert functional groups. Bioconjugation with protein and peptide substrates presents numerous challenges of functional group activation and selectivity, and transitional‐metal approaches provide important alternative solutions to these challenges. This article describes the development of boronic acid reagents for new selective approaches to modification of peptides and proteins, focusing primarily on catalytic C−X bond formation.
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