The smallest α,γ-peptide nanotubulet segments:: Cyclic α,γ-tetrapeptide dimers

Cyclic tetrapeptides in which alpha-amino acids alternate with cis-3-aminocycloalkanecarboxylic acids dimerize by forming hydrogen bonds between their alpha-faces but not between their gamma-faces, establishing the minimal structural requirements for the novel alpha,beta-peptide hybrids SPN.