RESUMO
The formylpeptides formyl-L-methionyl-L-leucyl-L-N-methylphenylalanine methyl ester 1, formyl-L-methionyl-L-leucyl-L-2-oxy-3-phenylpropionic acid methyl ester 2 and formyl-L-methionyl-L-leucyl-L-2-aminoxy-3-phenylpropionic acid methyl ester 3 were synthesized to investigate the role of the amide bond at position 3 in biological activity in human neutrophiles. Our results indicate that this amide bond is required for optimal chemotactic activity, but not for superoxide anion production.
Assuntos
Dipeptídeos/farmacologia , N-Formilmetionina Leucil-Fenilalanina/análogos & derivados , N-Formilmetionina Leucil-Fenilalanina/farmacologia , Neutrófilos/efeitos dos fármacos , Fenilpropionatos/farmacologia , Sítios de Ligação , Ligação Competitiva , Quimiotaxia de Leucócito/efeitos dos fármacos , Quimiotaxia de Leucócito/fisiologia , Dipeptídeos/química , Humanos , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Muramidase/metabolismo , N-Formilmetionina Leucil-Fenilalanina/química , Neutrófilos/metabolismo , Neutrófilos/fisiologia , Fenilpropionatos/química , Superóxidos/metabolismoRESUMO
The synthesis and biological activity on human neutrophils of for-Met-(gamma-lactam)-Leu-Phe-OMe [fM(gamma l)LP-OMe], an analogue of the chemotactic fMLP-OMe, are reported. The tetrapeptide evidences chemotactic activity as well as superoxide anion production and lysozyme release, although with lower efficacy when compared with the parent tripeptide.
Assuntos
Fatores Quimiotáticos/síntese química , Peptídeos/síntese química , Fatores Quimiotáticos/química , Fatores Quimiotáticos/farmacologia , Quimiotaxia de Leucócito/efeitos dos fármacos , Grânulos Citoplasmáticos/efeitos dos fármacos , Grânulos Citoplasmáticos/enzimologia , Dextranos/química , Humanos , Técnicas In Vitro , Conformação Molecular , Muramidase/metabolismo , Neutrófilos/efeitos dos fármacos , Peptídeos/química , Peptídeos/farmacologia , Superóxidos/metabolismoRESUMO
The formylpeptides formyl-methionyl-N-methylleucyl-phenylalanine methyl ester [for-Met-(NMe)Leu-Phe-OMe] 1, formyl-methionyl-2-aminotetralin-2-carboxyl-phenylalanine methyl ester [for-Met-Atc-Phe-OMe] 2, formyl-methionyl-1,2,3,4-tetrahydroisoquinoline-3-carboxyl-phenylalanine methyl ester [for-Met-Tic-Phe-OMe] 3 and formyl-methionyl-2-aminoxy-4-methylvaleryl-phenylalanine methyl ester [for-Met-OLeu-Phe-OMe] 4 were synthesized in order to investigate the role of the amide bond at position 2 on biological activities on human neutrophils. Only analogue 2, which keeps the NH group at position 2, was found to retain activity though sterically encumbered.
Assuntos
N-Formilmetionina Leucil-Fenilalanina/análogos & derivados , Neutrófilos/química , Neutrófilos/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Quimiotaxia/efeitos dos fármacos , Humanos , Muramidase/química , Muramidase/efeitos dos fármacos , N-Formilmetionina Leucil-Fenilalanina/síntese química , N-Formilmetionina Leucil-Fenilalanina/química , N-Formilmetionina Leucil-Fenilalanina/farmacologia , Neutrófilos/metabolismo , Peptídeos/síntese química , Peptídeos/química , Peptídeos/farmacologia , Relação Estrutura-Atividade , Superóxidos/metabolismoRESUMO
Deltorphin analogues were substituted by a series of achiral C alpha,alpha-dialkyl cyclic alpha-amino acids (1-aminocycloalkane-1-carboxylic acids, Ac chi c, where chi = a hexane, pentane, or propane cycloalkane ring) in position 2, 3, 4, or 2 and 3 in deltorphin C, and in position 2 in [Ac6c2,-des-Phe3]deltorphin C hexapeptide. Receptor assays indicated that even though Ac6c2 and Ac6c3 exhibited a diminished Ki delta by ca. 20-fold (2.5-3.3 nM) relative to deltorphin C (Ki delta = 0.15 nM), selectivity was marginally elevated (Ki mu/Ki delta = 1250) or enhanced by about 70%, and both peptides fitted stringent iterative calculations for a two-site binding model (eta = 0.625 and 0.766, respectively, P < 0.0001). The disubstituted [Ac6c2,3]- or [Ac6c2,des-Phe3]deltorphin analogues yielded peptides with decreased Ki delta, such that the latter peptide was essentially inactive. The presence of Ac5c or Ac3c in place of Phe3 further diminished Ki delta (15.4 to 19.0 nM), yet delta selectivity only fell about one-half (Ki mu/Ki delta = 440 and 535, respectively), and only the former peptide fitted a two-site binding model (eta = 0.799). The replacement of Asp4 by Ac6c, Ac5c, or Ac3c produced essentially nonselective analogues through the acquisition of high mu affinities (2.5, 0.58 and 0.27 nM, respectively) while maintaining high delta affinities (Ki delta = 0.045-0.054 nM) which were about 3-fold greater than that of deltorphin C. Using pharmacological assays in vitro (mouse vas deferens and guinea pig ileum), position 3-substituted analogues all indicated substantial losses in bioactivity, whereas substitution by 1-aminocycloalkanes at the fourth position retained high delta activity. In fact, the bioactivity of [Ac3c4]deltorphin C indicated a peptide with relatively weak delta selectivity, which was comparable to the observations with the receptor binding data. In summary, the data confirmed that (i) delta selectivity occurs in the absence of D-chirality at position 2, (ii) the aromaticity of Phe3 is replaceable by an achiral residue with a hydrophobic ring-saturated side chain, and (iii) the acquisition of dual high-affinity analogues occurs through the elimination of the anionic function at position 4 and replacement by an amino acid with a hydrophobic side chain.
Assuntos
Oligopeptídeos/síntese química , Oligopeptídeos/farmacologia , Receptores Opioides delta/efeitos dos fármacos , Receptores Opioides mu/efeitos dos fármacos , Sequência de Aminoácidos , Animais , Sítios de Ligação , Cobaias , Íleo/efeitos dos fármacos , Técnicas In Vitro , Camundongos , Modelos Químicos , Dados de Sequência Molecular , Oligopeptídeos/metabolismo , Ensaio Radioligante , Receptores Opioides delta/metabolismo , Receptores Opioides mu/metabolismoRESUMO
In order to investigate the proper peptide backbone conformation able to elicit a biological activity, HCO-Met-Pro-Phe-OMe, HCO-Met-Ψ[COO]Leu-Phe-OMe, and HCO-Met-OLeu-Phe-OMe, analogues of the prototypical chemotactic peptide HCO-Met-Leu-Phe-OMe, were studied by CD and IR techniques. The results obtained comparing biological and conformational data evidence the critical presence of (i) the NH group at position 2, (ii) a rather flexible backbone, (iii) the chemical structure of the central residue which can affect the stability of a possible active conformer.