Hydrolysis of N-formylmethionyl chemotactic peptides by endopeptidase 24.11 and endopeptidase 24.15

Endopeptidase 24.11 (EP 24.11), a membrane-bound cell surface enzyme, modulates chemotactic responsiveness of neutrophils to f-Met-Leu-Phe. It is unknown if the enzyme degrades potent formylmethionyl tetrapeptides or if an enzyme with similar activities, endopeptidase 24.15 (EP 24.15), degrades formylated chemotactic peptides. In a study of five formylmethionyl tetrapeptides and f-Met-Leu-Phe, we found that EP 24.11 had high affinity for all peptides evaluated, although it did not effectively degrade f-Met-Ile-Leu-Phe. EP 24.15 had high affinity for three of the tetrapeptides, and for f-Met-Leu-Phe, although, for unclear reasons, it did not degrade f-Met-Ile-Leu-Phe or f-Met-Leu-Phe, the apparent natural products of Staphylococcus aureus and Escherichia coli, respectively.