The Importance of the Methionine Configuration in for-Met-Leu-Phe-OMe Biological Activities

for-d-Met-l-Leu-l-Phe-OMe was synthesized in order to understand the importance of the methionine configuration on human neutrophil biological activity. Our results show that both chemotactic response and lysozyme release are lower than those of the parent fMLP-OMe, indicating that the specific receptor pocket possesses a well-located, restricted positive area that does not completely face the d-Met residue. The triggering of superoxide anion production does not seem to be sensitive to this variation of the configuration.