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 tetrapepti des or if an enzyme with similar activities, endopeptidase 24.15 (EP 2 4.15), degrades formylated chemotactic peptides. In a study of five fo rmylmethionyl tetrapeptides and f-Met-Leu-Phe, we found that EP 24.11 had high affinity for all peptides evaluated, although it did not effe ctively degrade f-Met-Ile-Leu-Phe. EP 24.15 had high affinity for thre e of the tetrapeptides, and for f-Met-Leu-Phe, although, for unclear r easons, it did not degrade f-Met-Ile-Leu-Phe or f-Met-Leu-Phe, the app arent natural products of Staphylococcus aureus and Escherichia coli, respectively.