Multiplexed CuAAC Suzuki-Miyaura Labeling for Tandem Activity-Based Chemoproteomic Profiling.

Mass-spectrometry-based chemoproteomics has enabled the rapid and proteome-wide discovery of functional and potentially 'druggable' hotspots in proteins. While numerous transformations are now available, chemoproteomic studies still rely overwhelmingly on copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) or 'click' chemistry. The absence of bio-orthogonal chemistries that are functionally equivalent and complementary to CuAAC for chemoproteomic applications has hindered the development of multiplexed chemoproteomic platforms capable of assaying multiple amino acid side chains in parallel. Here, we identify and optimize Suzuki-Miyaura cross-coupling conditions for activity-based protein profiling and mass-spectrometry-based chemoproteomics, including for target deconvolution and labeling site identification. Uniquely enabled by the observed orthogonality of palladium-catalyzed cross-coupling and CuAAC, we combine both reactions to achieve dual labeling. Multiplexed targeted deconvolution identified the protein targets of bifunctional cysteine- and lysine-reactive probes.

Regulating Transition-Metal Catalysis through Interference by Short RNAs.

Herein we report the discovery of a AuI -DNA hybrid catalyst that is compatible with biological media and whose reactivity can be regulated by small complementary nucleic acid sequences. The development of this catalytic system was enabled by the discovery of a novel AuI -mediated base pair. We found that AuI binds DNA containing C-T mismatches. In the AuI -DNA catalyst's latent state, the AuI ion is sequestered by the mismatch such that it is coordinatively saturated, rendering it catalytically inactive. Upon addition of an RNA or DNA strand that is complementary to the latent catalyst's oligonucleotide backbone, catalytic activity is induced, leading to a sevenfold increase in the formation of a fluorescent product, forged through a AuI -catalyzed hydroamination reaction. Further development of this catalytic system will expand not only the chemical space available to synthetic biological systems but also allow for temporal and spatial control of transition-metal catalysis through gene transcription.