Synthetic homo-oligomethionine chemoattractants. Conformation-activity study

Using solution methods, we have synthesized several series of L-methionine homooligopeptides from the dipeptide to the hexapeptide with either a free α-carboxyl function or different C-blocking groups (methoxy, benzyloxy, benzy-lamino) and with N-blocking groups of either the amide type (formyl, pivaloyl) or the urethane type (tert.-butyloxycarbonyl). Compounds were compared to determine the combined effect of main-chain length and presence and nature of N- and C-blocking groups on conformation-activity relationship. Each peptide was tested for its ability to induce rabbit peritoneal polymorphonuclear leukocytes in the presence of cytochalasin B to secrete granule enzymes. In parallel, a conformational analysis was carried out in the solid state and in solution, using infrared absorption and circular dichroism. The biological and conformational data are discussed in relation to a recently proposed model of the chemotactic peptide receptor of rabbit neutrophils.