Lysine monomethylation (Kme) is an impactful post-translational modification (PTM) responsible for regulating biological processes and implicated in diseases,t hus there is great interest in identifying these methylation marks globally.However,the progress in this area has been challenging because the addition of as mall methyl group on lysine leads to negligible change in the bulk, charge,a nd hydrophobicity.H erein, we report an empowering chemical technology selective triazenation reaction, which we term "STaR", of secondary amines using arene diazonium salts to achieve highly selective,r apid, and robust tagging of Kme peptides from ac omplex mixture under biocompatible conditions. Although the resulting triazene-linkage with Kme is stable,we highlight the efficient decoupling of the triazene-conjugate to affordunmodified starting components under mild conditions when desired. Our work establishes au nique chemoselective, traceless bioconjugation strategy for the selective enrichment of Kme PTMs.
Silencing genes in insects by introducing double-stranded RNA (dsRNA) in the diet holds promise as a new pest management method. It has been demonstrated that nanoparticles (NPs) can potentiate dsRNA silencing effects by promoting cellular internalization and protecting dsRNA against early degradation. However, many mysteries of how NPs and dsRNA are internalized by gut epithelial cells and, subsequently, transported across the midgut epithelium remain to be unraveled. The sole purpose of the current study is to investigate the role of endocytosis and transcytosis in the transport of branched amphipathic peptide nanocapsules (BAPCs) associated with dsRNA through midgut epithelium cells. Spodoptera frugiperda midguts and the epithelial cell line Sf9, derived from S. frugiperda , were used to study transcytosis and endocytosis, respectively. Results suggest that clathrin-mediated endocytosis and macropinocytosis are largely responsible for cellular uptake, and once within the midgut, transcytosis is involved in shuttling BAPCs–dsRNA from the lumen to the hemolymph. In addition, BAPCs were not found to be toxic to Sf9 cells or generate damaging reactive species once internalized.
Here we solve a long-standing challenge of the siteselective modification of secondary amides and present a simple twostep, metal-free approach to selectively modify a particular secondary amide in molecules containing multiple primary and secondary amides. Density functional theory (DFT) provides insight into the activation of C−N bonds. This study encompasses distinct chemical advances for late-stage modification of peptides thus harnessing the amides for the incorporation of various functional groups into natural and synthetic molecules.
Lysine monomethylation (Kme) is an impactful post‐translational modification (PTM) responsible for regulating biological processes and implicated in diseases, thus there is great interest in identifying these methylation marks globally. However, the progress in this area has been challenging because the addition of a small methyl group on lysine leads to negligible change in the bulk, charge, and hydrophobicity. Herein, we report an empowering chemical technology selective triazenation reaction, which we term “STaR”, of secondary amines using arene diazonium salts to achieve highly selective, rapid, and robust tagging of Kme peptides from a complex mixture under biocompatible conditions. Although the resulting triazene‐linkage with Kme is stable, we highlight the efficient decoupling of the triazene‐conjugate to afford unmodified starting components under mild conditions when desired. Our work establishes a unique chemoselective, traceless bioconjugation strategy for the selective enrichment of Kme PTMs.
Development of novel and specific insect pest management methods is critical for overcoming pesticide resistance and off-target effects. Gene silencing through consumption of double stranded (dsRNA) by insects shows promise in this area. Association of dsRNA with nanoparticles confers protection against nucleases, and can also promote translocation of dsRNA across the midgut epithelial cell membranes, and overall enhance gene knockdown effects. However, many mysteries of how nanoparticles and dsRNA are internalized by cells and subsequently transported across the midgut epithelium remain to be unraveled. In this article, we investigate the role of endocytosis and transcytosis in the uptake and transport of dsRNA and nanoparticles through midgut epithelium cells. Spodoptera frugiperda (Sf9) cells and branched amphiphilic peptide nano-capsules (BAPCs) were used as an experimental model. Additionally, analyses of reactive oxygen and nitrogen species (ROS/RNS) were performed to demonstrated that cell viability was minimally impacted by the BAPCs-dsRNA complex. Results suggests that clathrin-mediated endocytosis and macropinocytois are largely responsible for cellular uptake, and once within the midgut, transcytosis is involved in shuttling BAPCs from the lumen to the hemolymph. BAPCs were not found to be toxic to Sf9 cells or generate damaging reactive species once internalized. This opens up further possibilities for BAPCs as a new insect pest management method.
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