2026-04-13T02:09:45Zhttps://recercat.cat/oai/requestoai:recercat.cat:2445/2244242026-04-07T22:42:34Zcom_2072_1057col_2072_478917col_2072_478933
RECERCAT
author
Sánchez Campillo, Iván
author
Blanco Canosa, Juan B.
2025-11-21T11:30:17Z2025-11-21T11:30:17Z2024-10-30
Native chemical ligation (NCL) ligates two unprotected peptides in an aqueous buffer. One of the fragments features a C-terminal α-thioester functional group, and the second bears an N-terminal cysteine. The reaction mechanism depicts two steps: an intermolecular thiol–thioester exchange resulting in a transient thioester, followed by an intramolecular S-to-N acyl shift to yield the final native peptide bond. Although this mechanism is well established, the direct observation of the transient thioester has been elusive because the fast intramolecular rearrangement prevents its accumulation. Here, the use of α-selenoester peptides allows a faster first reaction and an early buildup of the intermediate, enabling its quantification and the kinetic monitoring of the first and second steps. The results show a correlation between the steric hindrance in the α-thioester residue and the rearrangement rate. In bulky residues, the S-to-N acyl shift has a significant contribution to the overall reaction rate. This is particularly notable for valine and likely for other similar β-branched amino acids.
cc by-nc-nd (c) Sánchez Campillo, Iván et al., 2024 http://creativecommons.org/licenses/by-nc-nd/3.0/es/ info:eu-repo/semantics/openAccess
Cinètica química
Síntesi proteica
Pèptids
Chemical kinetics
Protein synthesis
Peptides
Kinetic and Mechanistic Studies of Native Chemical Ligation with Phenyl α-Selenoester Peptides
info:eu-repo/semantics/article info:eu-repo/semantics/publisherVersion