Peptide stapling exerts profound effects on key peptide properties, including metabolic stability, cell membrane permeability, and conformational constraint. Herein, we report a mild and efficient 2,4-dichloro-1,3,5-triazine-mediated stapling strategy for the selective cross-linking of lysine side-chain amines. This approach furnishes macrocyclic peptides of varying ring sizes. This method features broad functional group compatibility with most natural amino acid residues (His, Trp, Arg, Tyr, Ser and Thr), as well as N-terminal α-amino and C-terminal carboxylate moieties, whereas cysteine is not tolerated in this transformation. For the representative stapled macrocyclic peptides, the 1,3,5-triazine bridge significantly enhanced proteolytic stability, membrane permeability and helical propensity, and potentiated their antiproliferative activity against multiple cancer cell lines.
Protein phosphatase 2 A (PP2A) achieves signaling specificity through regulatory B subunits, but the chemical and structural determinants of regulatory-subunit recognition surfaces remain incompletely defined. The first PP2A-B55α complex structure identified a regulatory groove on the β-propeller surface, spatially separated from the catalytic site and occupied by a FAM122A regulatory segment. This groove therefore represents a macromolecular recognition surface that can be systematically probed for cyclic peptide engagement. Here, 8466 cyclic peptides from CycPeptMPDB were screened against the B55α regulatory groove, and KarmaDock score-based ranking prioritized seven representative cyclic peptides for detailed structural and energetic analysis. Refined simulations showed peptide-dependent modulation of conformational stability, convergence to stable bound states, selective stabilization of the regulatory groove, and retained flexibility of the extended A-subunit arm. Triplicate and extended simulations of P-659, together with triplicate simulations of the top candidate P-589, further supported reproducible structural behavior and binding energetics. Persistent hydrogen-bonding patterns suggested peptide-specific anchoring through Asp190, Asp197, Asp333, Tyr330, Ser280, and Lys345. Peptide binding was accompanied by the expected displacement of solvent from the solvent-exposed groove interior and localized reorganization of interfacial hydration, while residue-wise thermodynamic profiling identified Lys81, Met215, Glu216, Phe273, Tyr330, Asp333, and Phe336 as key solvent-response residues. Alanine scanning identified Asp197 as the principal energetic hotspot, with ligand-specific contributions from Ser280, Tyr330, and Asp333. Binding free-energy calculations indicated balanced gas-phase and solvation contributions, with P-589 showing the most favorable relative MM-GBSA binding-energy estimate among the analyzed peptides (ΔGTOTAL = -61.84 ± 0.43 kcal/mol). Together, these data establish a computational, structure-, dynamics-, and energetics-resolved framework for cyclic peptide recognition at the PP2A-B55α regulatory groove and define testable hypotheses for experimental validation.
Muhammad Waqas, Li Xuan, Haoke Zhang et al.· International Journal of Bio...· 0 citations
We use cookies to run the site and, with your consent, for analytics and to show ads.
See our Cookie Policy.
