A compound comprising at least one looped peptide structure attached via at least one alkylamino linkage to a scaffold. Preferably the looped peptide structure is a Bicycle structure comprising two peptide loops attached to the scaffold via two alkylamino linkages and one thioether linkage, one of the linkages being common to both loops. Also provided is a method of making a compound comprising at least one looped peptide structure attached via at least one alkylamino linkages to a scaffold, the method comprising: providing a peptide having at least two residues selected from cysteine, diaminopropionic acid, β-N-Alkyldiaminopropionic acid and β-N-Alkyldiaminopropionic acid, provided that at least one of the residues is diaminopropionic acid, β-N-Alkyldiaminopropionic acid and β-N-Alkyldiaminopropionic acid, providing a scaffold molecule having at least two reactive sites for forming alkylamino or thioether linkages with the said at least two residues； and forming said linkages between the peptide and the scaffold molecule.
