Rotaxane-based propeptides: protection and enzymatic release of a bioactive pentapeptide.

Ring of protection: A [2]rotaxane 1 protects and selectively releases a bioactive pentapeptide. The rotaxane macrocycle provides a defensive shield that very significantly improves the poor stability of the peptide to both individual peptidases and the cocktail of enzymes present in human plasma. Glycosidase-catalyzed cleavage of a carbohydrate ‘stopper’ in the rotaxane triggers release of the parent peptide