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We have developed a convenient method for the direct synthesis of peptide thioesters, versatile intermediates for peptide ligation and cyclic peptide synthesis. The technology uses a modified Boc SPPS strategy that avoids the use of anhydrous HF. Boc in situ neutralization protocols are used in combination with Merrifield hydroxymethyl resin and TFA/TMSBr cleavage. Avoiding HF extends the scope of Boc SPPS to post-translational modifications that are compatible with the milder cleavage conditions, demonstrated here with the synthesis of the phosphorylated protein CHK2. Peptide thioesters give easy, direct, access to cyclic peptides, illustrated by the synthesis of cyclorasin, a KRAS inhibitor.
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http://dx.doi.org/10.1002/anie.201607657 | DOI Listing |
Analyst
August 2025
Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Padualaan 8, Utrecht 3584 CH, The Netherlands.
Long-chain -acylation is the addition of long-chain fatty acids to cysteine residues on proteins. This lipid modification is essential for protein membrane association and signalling but presents analytical challenges due to both its hydrophobicity and the labile nature of thioester bonds. We developed and optimised a bottom-up mass spectrometry workflow tailored for the detection of long-chain -acylated peptides.
View Article and Find Full Text PDFNature
August 2025
Department of Chemistry, University College London, London, UK.
To orchestrate ribosomal peptide synthesis, transfer RNAs (tRNAs) must be aminoacylated, with activated amino acids, at their 2',3'-diol moiety, and so the selective aminoacylation of RNA in water is a key challenge that must be resolved to explain the origin of protein biosynthesis. So far, there have been no chemical methods to effectively and selectively aminoacylate RNA-2',3'-diols with the breadth of proteinogenic amino acids in water. Here we demonstrate that (biological) aminoacyl-thiols (1) react selectively with RNA diols over amine nucleophiles, promoting aminoacylation over adventitious (non-coded) peptide bond formation.
View Article and Find Full Text PDFMethods Mol Biol
August 2025
Centre de Biophysique Moléculaire (CBM), UPR 4301, CNRS, affiliated with Université d'Orléans, Orléans, France.
SUMOylation is a post-translational modification catalyzed by a multi-step enzymatic cascade. To gain structural biology insights into the last step of this process, where SUMO is transferred from a SUMO~UBC9 molecule onto a substrate, stable complexes with SUMO covalently linked to UBC9, the substrate, or both are essential. Here, building on previously published approaches and our experience, we describe detailed protocols for the generation of a simple stable mimetic of human SUMO~UBC9, as well as a stably SUMOylated version of a model substrate, the C-terminal domain of RANGAP1.
View Article and Find Full Text PDFLife Sci Alliance
October 2025
Cancer Research UK Scotland Institute, Glasgow, UK
RING family ubiquitin ligases (E3s) employ the RING domain to recruit the E2 thioester ubiquitin (E2∼Ub) intermediate to catalyze the transfer of ubiquitin (Ub) to substrates. A cationic Arg linchpin (LP) residue in the RING domain plays a key role in stabilizing the interface with E2∼Ub, but the identity of the LP residue varies across E3s. Here, we investigate how the LP residue contributes to ubiquitination.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
July 2025
Cluster of Excellence livMatS @FIT - Freiburg Center for Interactive Materials and Bioinspired Technologies, University of Freiburg, Georges-Köhler-Allee 105, 79110, Freiburg, Germany.
Nature has consistently selected homochiral building blocks from millions of possible diastereomers across diverse biomolecular structures to drive molecular recognition, catalysis and self-assembly. Despite its central role in biology, chirality's influence on chemically driven reaction networks remains unexplored. Here, we demonstrate that chiral aminoacyl phosphate esters, synthetic analogs of biological acylating intermediates, drive self-assembly and reaction pathways, that are modulated purely by their configuration, without the need for changes in functional groups.
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