Conformational investigations on analogs of inflammation response inducing chemotactic tripeptide fMLP

Chemotactic tripeptides incorporating at position 2 alpha-aminoacid residues with unsaturated side chains

New N-For-Met-Leu-Phe-OMe (fMLF-OMe) analogues incorporating three different gamma-delta-didehydro-alpha-aminoacid residues (namely: Alg = (S)-Allylglycine; Dag = Diallylglycine; Cpg = 1-Aminocyclopent-3-ene-1-carboxylic acid) replacing the native (S)-Leucine have been synthesized and their activity towards human neutrophils has been evaluated in comparison with that shown by the reference tripeptide fMLF-OMe. Chemotaxis, lysozyme release and superoxide anion production have been measured. (1)H NMR titration experiments and NOESY spectrum of the Cpg containing model 10 have been discussed in order to ascertain the preferred solution conformations. A fully extended (C(5)) conformation at position 2 and a folded conformation with two consecutive gamma-turns (C(7) structure) have been proposed for the Dag and Cpg containing tripeptides, respectively.

Synthesis, conformation and biological activity of centrally modified pseudopeptidic analogues of For-Met-Leu-Phe-OMe

For-Met-betaAlapsi[CSNH]-Phe-OMe (3), For-Met-betaAlapsi[CH2NH]-Phe-OMe (5), For-Met-NH-pC6H4-SO(2-Phe-OMe 8a), For-Met-NH-mCH4-SO2-Phe-OMe (8b) and the corresponding N-Boc precursors (2, 4, 7a, b) have been synthesized and their activity towards human neutrophils has been evaluated in comparison with that shown by the reference tripeptide For-Met-Leu-Phe-OMe (fMLF-OMe). Chemotaxis, lysozyme release and superoxide anion production have been measured. (1)H NMR titration experiments and IR spectra have been discussed in order to ascertain the preferred solution conformation adopted by the tripeptide 3 with particular reference to the presence of a folded conformation centred at the centrally positioned thionated beta-residue.

Alpha-peptide/beta-sulfonamidopeptide hybrids: analogs of the chemotactic agent for-Met-Leu-Phe-OMe

In order to gain information on the activity shown by alpha-peptide/beta-sulfonamidopeptide hybrid analogs of the potent chemotactic agent fMLF-OMe, a structure-activity study is reported on N-Boc- and N-formyl tripeptide models containing an aminoalkanesulfonic acid as central residue. Directed migration (chemotaxis), superoxide anion production, and lysozyme release have been measured. The biochemical functions and the conformational properties of the new compounds are discussed and related to previously studied models containing beta-residues.