ABSTRACT
The biological action of a series of Met-Ile-Phe-Leu analogues was analyzed on human neutrophils, to evaluate their ability to interact with formylpeptide receptors and to induce the related neutrophil responses. Three in vitro assays were carried out: receptor binding, chemotaxis and superoxide anion release. Our results demonstrate that formyl-Met-Ile-Phe-Leu derivatives act as more potent full agonists than formyl-Met-Leu-Phe, the tripeptide normally used as a model chemoattractant for the study of cell functions. On the other hand, the presence of N-ureidoisopropyl substituent in tetrapeptides imparts weak partial agonist properties. It has furthermore been demonstrated that the C-terminal methyl esterification or amination weakly influences the properties of tetrapeptide homologues. Finally, t-Boc-Met-Ile-Phe-Leu derivatives do not appear able to interact with formylpeptide receptors.
Subject(s)
Neutrophils/drug effects , Oligopeptides/pharmacology , Receptors, Immunologic/agonists , Receptors, Peptide/agonists , Cell Movement/drug effects , Chemotaxis, Leukocyte/drug effects , Humans , In Vitro Techniques , Neutrophils/metabolism , Receptors, Formyl Peptide , Superoxides/metabolismABSTRACT
The conformation of several Phe-D-Leu-Phe-D-Leu-Phe analogues was analyzed using infrared absorption and circular dichroism. Their effect on human neutrophils was verified by receptor binding and chemotaxis assays. The results demonstrate that the compounds examined prefer an ordered conformation (beta-turn) in amphipatic environment, and that they are able to antagonize the neutrophil functions evoked by CHO-Met-Leu-Phe.
Subject(s)
N-Formylmethionine Leucyl-Phenylalanine/analogs & derivatives , N-Formylmethionine Leucyl-Phenylalanine/pharmacology , Receptors, Immunologic/antagonists & inhibitors , Receptors, Peptide/antagonists & inhibitors , Cell Movement/drug effects , Chemotaxis, Leukocyte/drug effects , Circular Dichroism , Humans , In Vitro Techniques , Molecular Conformation , N-Formylmethionine Leucyl-Phenylalanine/chemistry , Neutrophils/drug effects , Neutrophils/metabolism , Receptors, Formyl Peptide , Receptors, Immunologic/metabolism , Receptors, Peptide/metabolism , Spectrophotometry, Infrared , Spectrophotometry, Ultraviolet , Spectroscopy, Fourier Transform InfraredSubject(s)
Receptors, Immunologic/antagonists & inhibitors , Receptors, Peptide/antagonists & inhibitors , Humans , In Vitro Techniques , Molecular Conformation , N-Formylmethionine Leucyl-Phenylalanine/metabolism , Neutrophils/metabolism , Peptides/chemical synthesis , Peptides/chemistry , Peptides/pharmacology , Receptors, Formyl Peptide , Receptors, Immunologic/chemistry , Receptors, Peptide/chemistry , Structure-Activity Relationship , Superoxides/metabolismABSTRACT
The formyl tripeptides containing 2-azetidinecarboxylic acid 2, 2-piperidinecarboxylic acid 3 and norvaline 4 in position 2 were synthesized and their biological activity was evaluated. The conformation of peptides was studied by CD and FT-IR techniques. While 2 and 3 do not show either chemotactic activity or superoxide production, 4 retains both activities.
Subject(s)
Chemotactic Factors/chemistry , N-Formylmethionine Leucyl-Phenylalanine/analogs & derivatives , Neutrophils/drug effects , Oligopeptides/chemistry , Cell Movement , Chemotactic Factors/pharmacology , Humans , N-Formylmethionine Leucyl-Phenylalanine/chemistry , N-Formylmethionine Leucyl-Phenylalanine/pharmacology , Neutrophils/metabolism , Neutrophils/physiology , Oligopeptides/pharmacology , Protein Conformation , Solutions , Superoxides/metabolismABSTRACT
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.
Subject(s)
Dipeptides/pharmacology , N-Formylmethionine Leucyl-Phenylalanine/analogs & derivatives , N-Formylmethionine Leucyl-Phenylalanine/pharmacology , Neutrophils/drug effects , Phenylpropionates/pharmacology , Binding Sites , Binding, Competitive , Chemotaxis, Leukocyte/drug effects , Chemotaxis, Leukocyte/physiology , Dipeptides/chemistry , Humans , Magnetic Resonance Spectroscopy , Molecular Structure , Muramidase/metabolism , N-Formylmethionine Leucyl-Phenylalanine/chemistry , Neutrophils/metabolism , Neutrophils/physiology , Phenylpropionates/chemistry , Superoxides/metabolismABSTRACT
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.
Subject(s)
N-Formylmethionine Leucyl-Phenylalanine/analogs & derivatives , Neutrophils/chemistry , Neutrophils/drug effects , Cell Movement/drug effects , Chemotaxis/drug effects , Humans , Muramidase/chemistry , Muramidase/drug effects , N-Formylmethionine Leucyl-Phenylalanine/chemical synthesis , N-Formylmethionine Leucyl-Phenylalanine/chemistry , N-Formylmethionine Leucyl-Phenylalanine/pharmacology , Neutrophils/metabolism , Peptides/chemical synthesis , Peptides/chemistry , Peptides/pharmacology , Structure-Activity Relationship , Superoxides/metabolismABSTRACT
Synthetic peptides reproducing the proteolytic processing site of pro-ocytocin were studied by different spectroscopic techniques, including circular dichroism, Fourier transform infrared absorption, and mono and bidimensional nuclear magnetic resonance, in order to ascertain the possible role of three-dimensional structure in the recognition process by maturation enzymes. Experimental results were compared with energy minimization calculations and suggest that: (i) the region situated on the N-terminus of the Lys-Arg doublet may form a beta-turn; (ii) the sequential organization of the residues participating in the beta-turn determines the privileged relative orientation of the basic amino acid sidechains and the subtype of turn; and (iii) the peptide segment situated on the C-terminal side of the dibasic doublet may assume a helix arrangement. These findings, in spite of the limitations connected to the flexibility of linear peptides, seem to substantiate the hypothesis that structural motifs around the cleavage site could be important for recognition and processing. however, a straightforward correlation between details of the secondary structure and the in vitro reactivity toward a putative convertase is not yet possible.
Subject(s)
Arginine Vasopressin/chemistry , Neurophysins/chemistry , Oxytocin/analogs & derivatives , Peptides/chemistry , Protein Precursors/chemistry , Amino Acid Sequence , Arginine Vasopressin/metabolism , Binding Sites , Circular Dichroism , Magnetic Resonance Spectroscopy , Models, Molecular , Neurophysins/metabolism , Oxytocin/chemistry , Oxytocin/metabolism , Peptide Fragments/chemical synthesis , Peptide Fragments/chemistry , Peptides/chemical synthesis , Protein Conformation , Protein Precursors/metabolism , Protein Processing, Post-Translational , Protein Structure, Secondary , Spectroscopy, Fourier Transform InfraredABSTRACT
The synthesis and a conformational study of a number of homologues of the well known antibiotic, phytotoxic leucinostatin A are reported. The circular dichroism of all the compounds are discussed. Some conclusions on the SAR of these compounds are drawn. The influence of the alpha-helical conformation and/or the increased lipophile character on their interesting biological activities is emphasized.
Subject(s)
Anti-Bacterial Agents/chemistry , Antibiotics, Antineoplastic/chemistry , Peptides , Amino Acid Sequence , Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/pharmacology , Antibiotics, Antineoplastic/chemical synthesis , Antibiotics, Antineoplastic/pharmacology , Antimicrobial Cationic Peptides , Circular Dichroism , Gram-Positive Bacteria/drug effects , Microbial Sensitivity Tests , Molecular Sequence Data , Structure-Activity RelationshipABSTRACT
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.
ABSTRACT
The conformational flexibility of the [Thr6, Leu13 psi(CH2NH) Met14] bombesin (6-14) nonapeptide has been studied by CD and one- and two-dimensional (1D and 2D) nmr techniques. The CD and nmr parameters in different solvents and in a micellar environment (SDS) are compared with the data collected for the parent bombesin (BN) and [D-Phe12, Leu14]BN. A preliminary investigation on spantide is also reported. In particular, the results obtained from CD measurements indicate that there is a shift from random coil structures, in aqueous solutions, toward folded structures in apolar media (2,2,2-trifluoroethanol) and in a membrane-mimetic environment (40 mM SDS) for all three peptides, namely BN, [D-Phe12, Leu14]BN, and [Thr6, Leu13 psi(CH2NH) Met14]BN (6-14). Spantide, which also possesses some inhibitory activity against BN but very little sequence similarity, even in water, shows an ordered conformation. Nuclear magnetic resonance parameters such as backbone NH-alpha CH coupling constant values, amidic temperature coefficients, and the presence of only sequential nuclear Overhauser effects have not provided, so far, any clear evidence for a preferential ordered structure in the peptides studied, and this may be due to rapid exchange among different conformers in the nmr time scale.
Subject(s)
Bombesin/analogs & derivatives , Bombesin/antagonists & inhibitors , Oligopeptides/chemistry , Peptide Fragments/chemistry , Amino Acid Sequence , Bombesin/chemistry , Circular Dichroism , Magnetic Resonance Spectroscopy/methods , Molecular Sequence Data , Protein ConformationABSTRACT
The conformation flexibility of the tetradecapeptide hormone bombesin and its synthetic antagonist (DPhe12, Leu14)-bombesin has been studied using nuclear magnetic resonance and circular dichroism techniques. The spectral features observed indicate that the ordered structure present in the C-terminal pentapeptide moiety of native BBS is lost in the (DPhe12, Leu14) analog.
Subject(s)
Bombesin , Bombesin/analogs & derivatives , Bombesin/metabolism , Bombesin/pharmacology , Circular Dichroism , Magnetic Resonance Spectroscopy , Protein Conformation , Receptors, Bombesin , Receptors, Neurotransmitter/drug effects , Receptors, Neurotransmitter/metabolism , Structure-Activity RelationshipABSTRACT
The tetrapeptides CHO-Met-Leu-Phe-CO-NH-(CH2)n-COOMe (n = 1-5) have been synthesized. These peptides containing an omega-amino acid residue in position 4 exhibit a very high chemotactic activity. Like the chemotactic peptide CHO-Met-Leu-Phe-OMe, these tetrapeptides in solution undoubtedly adopt an "active" conformation which allows a strong interaction with the receptor on the human polymorphonuclear leukocyte surface.
Subject(s)
Chemotactic Factors/chemical synthesis , Chemotaxis, Leukocyte/drug effects , Oligopeptides/chemical synthesis , Cell Movement/drug effects , Chemical Phenomena , Chemistry , Chemotactic Factors/pharmacology , Humans , In Vitro Techniques , Molecular Conformation , Neutrophils/drug effects , Oligopeptides/pharmacology , Structure-Activity RelationshipABSTRACT
The conformational behavior of the chemotactic peptide analogs formylmethionylleucylphenylalanine methyl ester (CHO-Met-Leu-Phe-OMe) and formylmethionylleucylcyclohexylalanine methyl ester (CHO-Met-Leu-Cha-OMe) has been studied in solvents of different polarity by circular dichroism and infrared absorption. Both analogs and very probably the chemotactic peptide formylmethionylleucylphenylalanine (CHO-Met-Leu-Phe-OH) preferably adopt in solution a folded "active" conformation which allows a strong interaction with the receptor on the human polymorphonuclear leukocyte surface.
Subject(s)
Chemotaxis, Leukocyte , N-Formylmethionine Leucyl-Phenylalanine/analogs & derivatives , N-Formylmethionine Leucyl-Phenylalanine/chemical synthesis , Oligopeptides/chemical synthesis , Circular Dichroism , Humans , Leukocytes/drug effects , Leukocytes/physiology , Oligopeptides/pharmacology , Protein Conformation , Structure-Activity RelationshipABSTRACT
Two analogs of chemotactic peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine were examined for their capacity to activate several functions of human neutrophils. The C-terminus methyl ester derivative of the chemotactic peptide was found to possess strong biological activity and was able to induce levels of chemotaxis, enzyme secretion, and superoxide generation comparable to those observed with the same concentrations of N-formyl-L-methionyl-L-leucyl-L-phenylalanine. The analog containing a tert-butyloxycarbonyl group at the N-terminus, as well as the C-terminal methyl ester, was completely devoid of activity towards neutrophils. From these results, it appears that the free carboxyl group is not necessary for biological function. In contrast, the substituent at the N-terminus may play a critical role in the induction of the cellular response.
Subject(s)
Chemotaxis, Leukocyte , N-Formylmethionine Leucyl-Phenylalanine/analogs & derivatives , Neutrophils/physiology , Chemotaxis, Leukocyte/drug effects , Humans , In Vitro Techniques , Kinetics , Muramidase/blood , N-Formylmethionine Leucyl-Phenylalanine/pharmacology , Neutrophils/drug effects , Structure-Activity RelationshipABSTRACT
Dermorphins are potent opiate-like heptapeptides which have been isolated from the skin of South American frogs. The Circular Dichroism spectra carried out on dermorphin (Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2), on the analogous [L-Ala2] dermorphin and on N-terminal fragments suggest that, in solution, the native molecule possesses a peculiar folded conformation responsible for its pharmacological activity. The presence of alanine in D configuration and of aminoacid residues possessing a high "beta-turn" potential, seems to be the main reason for such active conformation.
Subject(s)
Endorphins/analysis , Oligopeptides/analysis , Amino Acid Sequence , Circular Dichroism , Opioid Peptides , Peptide Fragments , Protein Conformation , Spectrophotometry, UltravioletABSTRACT
The anti-inflammatory and analgesic activities of a series of 3-methyl-N-phenyl-1H-pyrazol-5-ylcarboxamides were investigated and compared with flufenamic acid. The compounds were synthesized by condensation of diketopiperazines 2 with the appropriate aniline. The pharmacological tests showed that some compounds have good anti-inflammatory activity in rat paw edema induced by carrageenin and low toxicity.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/chemical synthesis , Pyrazoles/chemical synthesis , Animals , Chemical Phenomena , Chemistry , Edema/drug therapy , Flufenamic Acid/toxicity , Lethal Dose 50 , Male , Pyrazoles/pharmacology , Pyrazoles/toxicity , Rats , Rats, Inbred StrainsABSTRACT
Two tripeptides, related to the chemotactic formyl-peptide, are tested for its ability to affect random and directional locomotion and to induce chemotaxis of polymorphonuclear leukocytes. The results indicate that the methyl ester of formyl-methyonyl-leucyl-phenylalanine possesses a biological activity towards human phagocytes, including a chemotactic potency, comparable to that of unmodified peptide. Therefore, the free carboxyl group does not seem essential to generate active leukoattractant. On the contrary, the replacement of the formyl group by the butyloxycarbonyl results in a drastic loss of biological activity. Our data may indicate that the two formyl-peptides interact with the same binding site on the cell membrane.
Subject(s)
Chemotaxis, Leukocyte/drug effects , N-Formylmethionine Leucyl-Phenylalanine/analogs & derivatives , Binding Sites , Humans , In Vitro Techniques , N-Formylmethionine Leucyl-Phenylalanine/pharmacology , Neutrophils/drug effectsABSTRACT
The synthesis of pyrazolyl-amides of aminoacids and peptides is described. The chemicals were tested for antifungal activity against wheat powdery mildew (Erysiphe graminis DC.), cucumber powdery mildew (Erysiphe cichoracearum DC.), wheat brown rust (Puccinia recondita Rob. ex Desm. f. sp. tritici Erikss et Henn.), celery leaf spot (Septoria Apii Briosi ed Cav. Chest.) and collar rot (Rhizoctonia solani Kuhn). Some of these compounds showed antifungal activity.
Subject(s)
Amides/pharmacology , Amino Acids/pharmacology , Fungicides, Industrial/pharmacology , Peptides/pharmacology , Amides/chemical synthesis , Amino Acids/chemical synthesis , Ascomycota/drug effects , Basidiomycota/drug effects , Fungicides, Industrial/chemical synthesis , Mitosporic Fungi/drug effects , Peptides/chemical synthesisABSTRACT
The synthesis of 4-nitroso-5-amminopyrazoles and of 4-nitroso-5-pyrazolylurethans and -ureas is described. The chemicals were tested for antifungal activity against Erysiphe graminis, Erysiphe cichoracearum, Puccinia recondita, Septoria apii and Rhizoctonia solani. A number of the described compounds showed some antifungal activity.
Subject(s)
Antifungal Agents/chemical synthesis , Nitroso Compounds/chemical synthesis , Pyrazoles/chemical synthesis , Microbial Sensitivity Tests , Nitroso Compounds/pharmacology , Pyrazoles/pharmacologyABSTRACT
A series of condensation products of cholic and dehydrocholic acids with (L)-aminoacids was prepared and tested in vitro for antimicrobial activity. The derivatives of cholic acid with basic aminoacids showed significant activity, especially marked when (L)-arginine was the condensed aminoacid.