RESUMO
The synthesis and biological properties of vinyl ester peptide-based molecules bearing linear N-terminal amino acids are reported. Compounds were tested in vitro for their capacity to inhibit the chymotryptic-, tryptic-like, and post-acidic activities of the proteasome. Some analogues showed selective inhibition of post-acidic (PGPH) activity, which is attributed to the beta1 subunit. Interestingly, active compounds demonstrated higher inhibitory activity toward 'standard' proteasomes than toward immunoproteasomes. The inhibitory potency was found to be related to the amino acidic sequence and to the length of the N-terminal residues. The new inhibitors demonstrated resistance to plasmatic proteases and a good capacity to permeate the cell membrane.
Assuntos
Peptídeos/química , Peptídeos/farmacologia , Complexo de Endopeptidases do Proteassoma/metabolismo , Inibidores de Proteassoma , Sequência de Aminoácidos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Humanos , Leucócitos Mononucleares/enzimologia , Peptídeos/síntese química , Relação Estrutura-AtividadeRESUMO
The conformation of several Met-Ile-Phe-Leu analogues was analyzed using circular dichroism and infra-red absorption. Their effect on human neutrophils was verified by receptor binding assays and measurements of lysozyme release. The results demonstrate that in amphipatic environments the compounds examined can be highly and weakly ordered in beta-turn structures, in dependence on their N-terminal substituents. The ability of the compounds to evoke neutrophil functions appears strongly and weakly influenced by N- and C-terminal modification, respectively.
Assuntos
Oligopeptídeos/síntese química , Receptores de Formil Peptídeo/agonistas , Fenômenos Químicos , Físico-Química , Dicroísmo Circular , Grânulos Citoplasmáticos/efeitos dos fármacos , Grânulos Citoplasmáticos/enzimologia , Humanos , Técnicas In Vitro , Lisossomos/efeitos dos fármacos , Lisossomos/metabolismo , Conformação Molecular , Muramidase/efeitos dos fármacos , Muramidase/metabolismo , Neutrófilos/efeitos dos fármacos , Neutrófilos/metabolismo , Oligopeptídeos/farmacologia , Solventes , Espectroscopia de Infravermelho com Transformada de Fourier , Relação Estrutura-AtividadeRESUMO
The biological action of several X-Phe-D-Leu-Phe-D-Leu-Z (X=3',5'-dimethylphenyl-ureido; Z=Phe, Lys, Glu, Tyr) analogues was analysed on human neutrophils to evaluate their ability to antagonize formyl-peptide receptors. X-Phe-D-Leu-Phe-D-Leu-Phe analogues obtained as C-terminal olo or amido derivatives and T-Phe-D-Leu-Phe-D-Leu-Phe analogues (T=thiazolyl-ureido) were also analysed. The activities of pentapeptide derivatives were compared with those of X-Phe-D-Leu-Phe-D-Leu-Phe chosen as reference antagonist. Our results demonstrate that X-Phe-D-Leu-Phe-D-Leu-Phe-olo, X-Phe-D-Leu-Phe-D-Leu-Glu and X-Phe-D-Leu-Phe-D-Leu-Tyr are more active antagonists than X-Phe-D-Leu-Phe-D-Leu-Phe. The presence of Lys (X-Phe-D-Leu-Phe-D-Leu-Lys) seems, instead, to inhibit the formyl-peptide receptor antagonist properties. The presence of the N-terminal thiazolyl-ureido group seems to considerably contribute to the receptor antagonist properties of T-Phe-D-Leu-Phe-D-Leu-Phe-OH. The introduction of the C-terminal methyl ester (T-Phe-D-Leu-Phe-D-Leu-Phe-OMe) or amido group (X-Phe-D-Leu-Phe-D-Leu-Phe-NH2) appears detrimental for the affinity and formyl-peptide receptor antagonist properties of the Phe-D-Leu-Phe-D-Leu-Phe derivatives. The examined peptides inhibit superoxide anion production and lysozyme release more efficaciously than neutrophil chemotaxis.