Stable isotope containing peptides as probes of ligand—receptor interactions: Deutero-formyl-methionyl-leucyl-phenylalanine

The synthesis and biological evaluation of the stable isotope containing chemotactic peptide, deuteroformyl-methionyl-leucyl-phenylalanine (C2DO-Met-Leu-Phe-OH) is reported. The results, using lysosomal enzyme release from cytochalasin B-treated rabbit neutrophils for biological evaluation indicates a 3–4 fold enhancement over CHO-Met-Leu-Phe-OH itself. This is consistent with previous speculation that the formyl proton hydrogen bonds with a critical area of the chemotactic peptide receptor of rabbit neutrophils.