NXO Building Blocks for Backbone Modification of Peptides and Preparation of Pseudopeptides

摘要

The design and synthesis of novel building blocks for peptide modification, termed “NXO”, is reported. We describe the utility of these building blocks to prepare new pseudo- and oligopeptides and demonstrate the efficient assembly of modified tripeptides using both conventional liquid phase peptide synthesis and solid supported synthesis. Pertaining to the study of NXO in peptide mimicry, the structure of NXO-incorporating tripeptide β-strand mimics was investigated in the NLAlaO incorporating β-sheet model compound 13. Evidenced by spectroscopy and computation, 13 selectively adopts a β-structure in chloroform and characteristically samples the NXO-modified backbone site in the core β-sheet region.ROESY(HNMR)and molecular dynamics data suggest that when disrupting the cross-strand hydrogen-bonding pattern by switching the solvent from CDCl3 to d3-MeOH, the main conformation with peptide and NXO-peptide backbones similar to that in root mean square deviation of corresponding backbone atoms (rmsd) is preserved.