A hydrophilic residue at position 2 can improve specific biological responses in fMLP-OMe analogs

The peptides for-Met-Ser-Phe-OMe 1, for-Met-Cys-Phe-OMe 2, for-Met-Lys-Phe- OMe 3, and for-Met-Tyr-Phe-OMe 4 were synthesized in order to investigate t he importance of a hydrophilic side-chain on the residue at position 2 on b iological activities of human neutrophils. Our results seem to highlight th at this type of substitution does not facilitate good chemotaxis, although it elicits both superoxide anion production and particularly lysozyme relea se, in some cases even more potent than the parent fMLP-OMe, if the hydroph ilicity is associated with steric hindrance.