A nonspecific exopeptidase, aminopeptidase N (APN), is inhibited sequence-specifically by a synthetic host, cucurbituril (Q7), which binds with high affinity and specificity to N-terminal phenylalanine (Phe) and 4-(aminomethyl)phenylalanine (AMPhe) and prevents their removal from the peptide. Liquid chromatography experiments demonstrated that in the presence of excess Q7, APN quantitatively converts the pentapeptides Thr-Gly-Ala-X-Met into the dipeptides X-Met (X = Phe, AMPhe). The resulting Q7-bound products are completely stable to proteolytic digestion for at least 24 h. Structure–activity studies revealed a direct correlation between the extent of protection of an N-terminal amino acid and its affinity for Q7. Therefore, Q7 provides predictable sequence-specificity to an otherwise nonspecific protease and enables the production of a single peptide product. Conversely, APN uncovers a high-affinity epitope that is subsequently bound by Q7, and thus this approach should also facilitate the molecular recognition of peptides.
Document Object Identifier (DOI)
Logsdon, L. A., & Urbach, A. R. (2013). Sequence-specific inhibition of a nonspecific protease. Journal of the American Chemical Society, 135, 11414-11416. doi: 10.1021/ja406032x
Journal of the American Chemical Society