Search

Abstract Chemoselective modification of specific residues within a given protein poses a significant challenge, as the microenvironment of amino acid residues in proteins is variable. Developing a universal molecular platform with tunable chemical warheads can provide powerful tools for precisely labeling specific amino acids in proteins. Cysteine and lysine are hot targets for chemoselective modification, but current cysteine/lysine‐selective warheads face challenges due to cross‐reactivity and unstable reaction products. In this study, a versatile fluorescent platform is developed for highly selective modification of cysteine/lysine under biocompatible conditions. Chloro‐ or phenoxy‐substituted NBSe derivatives effectively labeled cysteine residues in the cellular proteome with high specificity. This finding also led to the development of phenoxy‐NBSe phototheragnostic for the diagnosis and activatable photodynamic therapy of GSH‐overexpressed cancer cells. Conversely, alkoxy‐NBSe derivatives are engineered to selectively react with lysine residues in the cellular environment, exhibiting excellent anti‐interfering ability against thiols. Leveraging a proximity‐driven approach, alkoxy‐NBSe probes are successfully designed to demonstrate their utility in bioimaging of lysine deacetylase activity. This study also achieves integrating a small photosensitizer into lysine residues of proteins in a regioselective manner, achieving photoablation of cancer cells activated by overexpressed proteins.

Abstract Covalent probes coupled with chemical proteomics represent a powerful method for investigating small molecule and protein interactions. However, the creation of a reactive warhead within various ligands to form covalent probes has been a major obstacle. Herein, we report a convenient and robust process to assemble a unique electrophile, an α-acyloxyenamide, through a one-step late-stage coupling reaction. This procedure demonstrates remarkable tolerance towards other functional groups and facilitates ligand-directed labeling in proteins of interest. The reactive group has been successfully incorporated into a clinical drug targeting the EGFR L858R mutant, erlotinib, and a pan-kinase inhibitor. The resulting probes have been shown to be able to covalently engage a lysine residue proximal to the ATP-binding pocket of the EGFR L858R mutant. A series of active sites, and Mg2+, ATP-binding sites of kinases, such as K33 of CDK1, CDK2, CDK5 were detected. This is the first report of engaging these conserved catalytic lysine residues in kinases with covalent inhibition. Further application of this methodology to natural products has demonstrated its success in profiling ligandable conserved lysine residues in whole proteome. These findings offer insights for the development of new targeted covalent inhibitors (TCIs).

This paper investigated the static in vitro degradation behavior of poly(L-lactic acid) (PLLA)-oriented microcellular materials. The study compared the influence of different molecular chains and internal morphological structures on water penetration into the material. Also, the relationship between thse self-accelerated degradation caused by ester bond breakage and reduced material molecular weight and mechanical properties was explored. Furthermore, the mechanism behind the static in vitro degradation of oriented microcellular PLLA materials in simulated human body fluid was explored, laying the foundation for regulating the mechanical performance decline of oriented microcellular biomimetic bone repair materials to match specific bone healing periods.