Connecting Hydrophobic Surfaces in Cyclic Peptides Increases Membrane Permeability.
Hoang, H.N., Hill, T.A., Fairlie, D.P.(2021) Angew Chem Int Ed Engl 60: 8385-8390
- PubMed: 33185961 
- DOI: https://doi.org/10.1002/anie.202012643
- Primary Citation of Related Structures:  
7L96, 7L98, 7L9D - PubMed Abstract: 
N- or C-methylation in natural and synthetic cyclic peptides can increase membrane permeability, but it remains unclear why this happens in some cases but not others. Here we compare three-dimensional structures for cyclic peptides from six families, including isomers differing only in the location of an N- or Cα-methyl substituent. We show that a single methyl group only increases membrane permeability when it connects or expands hydrophobic surface patches. Positional isomers, with the same molecular weight, hydrogen bond donors/acceptors, rotatable bonds, calculated LogP, topological polar surface area, and total hydrophobic surface area, can have different membrane permeabilities that correlate with the size of the largest continuous hydrophobic surface patch. These results illuminate a key local molecular determinant of membrane permeability.
Organizational Affiliation: 
Division of Chemistry and Structural Biology and ARC Centre of Excellence for Innovations in Peptide and Protein Science, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.