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1.
Molecules ; 29(7)2024 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-38611824

RESUMO

Pain affects one-third of the global population and is a significant public health issue. The use of opioid drugs, which are the strongest painkillers, is associated with several side effects, such as tolerance, addiction, overdose, and even death. An increasing demand for novel, safer analgesic agents is a driving force for exploring natural sources of bioactive peptides with antinociceptive activity. Since the G protein-coupled receptors (GPCRs) play a crucial role in pain modulation, the discovery of new peptide ligands for GPCRs is a significant challenge for novel drug development. The aim of this review is to present peptides of human and animal origin with antinociceptive potential and to show the possibilities of their modification, as well as the design of novel structures. The study presents the current knowledge on structure-activity relationship in the design of peptide-based biomimetic compounds, the modification strategies directed at increasing the antinociceptive activity, and improvement of metabolic stability and pharmacodynamic profile. The procedures employed in prolonged drug delivery of emerging compounds are also discussed. The work summarizes the conditions leading to the development of potential morphine replacements.


Assuntos
Analgésicos , Peptídeos , Animais , Humanos , Analgésicos/farmacologia , Analgésicos/uso terapêutico , Peptídeos/farmacologia , Morfina , Dor , Analgésicos Opioides/farmacologia , Analgésicos Opioides/uso terapêutico
2.
Neurochem Res ; 49(4): 895-918, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38117448

RESUMO

Naturally occurring peptides, such as rubiscolins derived from spinach leaves, have been shown to possess some interesting activities. They exerted central effects, such as antinociception, memory consolidation and anxiolytic-like activity. The fact that rubiscolins are potent even when given orally makes them very promising drug candidates. The present work tested whether rubiscolin-6 (R-6, Tyr-Pro-Leu-Asp-Leu-Phe) analogs have neuroprotective and anti-inflammatory effects. These hypotheses were tested in the 6-hydroxydopamine (6-OHDA) injury model of human neuroblastoma SH-SY5Y and lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. The determination of reactive oxygen species (ROS), mitochondrial membrane potential (MMP), Caspase-3 activity, lipid peroxidation and nitric oxide (NO) production allowed us to determine the effects of peptides on hallmarks related to Parkinson's Disease (PD) and inflammation. Additionally, we investigated the impact of R-6 analogs on serine-threonine kinase (also known as protein kinase B, AKT) and mammalian target of rapamycin (mTOR) activation. The treatment with analogs 3 (Tyr-Inp-Leu-Asp-Leu-Phe-OH), 5 (Dmt-Inp-Leu-Asp-Leu-Phe-OH) and 7 (Tyr-Inp-Leu-Asp-Leu-Phe-NH2) most effectively prevented neuronal death via attenuation of ROS, mitochondrial dysfunction and Caspase-3 activity. Peptides 5 and 7 significantly increased the protein expression of the phosphorylated-AKT (p-AKT) and phosphorylated-mTOR (p-mTOR). Additionally, selected analogs could also ameliorate LPS-mediated inflammation in macrophages via inhibition of intracellular generation of ROS and NO production. Our findings suggest that R-6 analogs exert protective effects, possibly related to an anti-oxidation mechanism in in vitro model of PD. The data shows that the most potent peptides can inhibit 6-OHDA injury by activating the PI3-K/AKT/mTOR pathway, thus playing a neuroprotective role and may provide a rational and robust approach in the design of new therapeutics or even functional foods.


Assuntos
Neuroblastoma , Fármacos Neuroprotetores , Doença de Parkinson , Fragmentos de Peptídeos , Ribulose-Bifosfato Carboxilase , Humanos , Apoptose , Proteínas Proto-Oncogênicas c-akt/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Oxidopamina/toxicidade , Caspase 3/metabolismo , Lipopolissacarídeos/farmacologia , Linhagem Celular Tumoral , Neuroblastoma/metabolismo , Doença de Parkinson/tratamento farmacológico , Serina-Treonina Quinases TOR/metabolismo , Peptídeos/uso terapêutico , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Inflamação/tratamento farmacológico , Fármacos Neuroprotetores/farmacologia , Fármacos Neuroprotetores/uso terapêutico
3.
Int J Mol Sci ; 23(20)2022 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-36293553

RESUMO

Recently, mixed opioid/NOP agonists came to the spotlight for their favorable functional profiles and promising outcomes in clinical trials as novel analgesics. This study reports on two novel chimeric peptides incorporating the fragment Tyr-c[D-Lys-Phe-Phe]Asp-NH2 (RP-170), a cyclic peptide with high affinity for µ and κ opioid receptors (or MOP and KOP, respectively), conjugated with the peptide Ac-RYYRIK-NH2, a known ligand of the nociceptin/orphanin FQ receptor (NOP), yielding RP-170-RYYRIK-NH2 (KW-495) and RP-170-Gly3-RYYRIK-NH2 (KW-496). In vitro, the chimeric KW-496 gained affinity for KOP, hence becoming a dual KOP/MOP agonist, while KW-495 behaved as a mixed MOP/NOP agonist with low nM affinity. Hence, KW-495 was selected for further in vivo experiments. Intrathecal administration of this peptide in mice elicited antinociceptive effects in the hot-plate test; this action was sensitive to both the universal opioid receptor antagonist naloxone and the selective NOP antagonist SB-612111. The rotarod test revealed that KW-495 administration did not alter the mice motor coordination performance. Computational studies have been conducted on the two chimeras to investigate the structural determinants at the basis of the experimental activities, including any role of the Gly3 spacer.


Assuntos
Analgésicos Opioides , Receptores Opioides , Animais , Camundongos , Analgésicos Opioides/uso terapêutico , Receptores Opioides/agonistas , Receptores Opioides kappa , Antagonistas de Entorpecentes/farmacologia , Receptores Opioides mu/agonistas , Simulação de Acoplamento Molecular , Ligantes , Relação Dose-Resposta a Droga , Naloxona , Analgésicos/farmacologia , Peptídeos/farmacologia , Quimera , Peptídeos Cíclicos
4.
J Pept Sci ; 23(12): 864-870, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29110363

RESUMO

Three novel morphiceptin analogs, in which Pro in position 2 and/or 4 was replaced by cis-4-aminoproline connected with the preceding amino acid through the primary amino group, were synthesized. The opioid receptor affinities, functional assay results, enzymatic degradation studies and experimental and in silico structural analysis of such analogs are presented. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.


Assuntos
Endorfinas/química , Peptídeos/síntese química , Peptídeos/farmacologia , Receptores Opioides/metabolismo , Animais , Simulação por Computador , Humanos , Simulação de Dinâmica Molecular , Peptídeos/química , Ligação Proteica , Relação Estrutura-Atividade
5.
Anal Chim Acta ; 986: 71-81, 2017 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-28870327

RESUMO

A novel class of ionization tags, based on 5-azoniaspiro[4.4]nonyl (ASN+) scaffold were designed for improved analysis of peptides by electrospray tandem mass spectrometry (ESI-MS/MS). A new labeling agent, 1-{[3-oxo-3-(pentafluorophenoxy)propyl]carbamoyl}-5-azoniaspiro[4.4]nonane, was developed to react with amine and/or thiol group-containing peptides. The ionization efficiency of peptides resulting from derivatization was enhanced 10-100 fold, depending on the peptide sequence and hydrophobicity of the ionization tag. The proposed tags are completely stable during collision-induced dissociation (CID) experiments: they do not undergo unwanted fragmentation via Hofmann elimination and, more importantly, they cannot be removed by intermolecular nucleophilic attack. Moreover, CID of the derivatized peptide ions generates a dominant series of y-type fragment ions with a high sequence coverage. The proposed procedure was successfully tested on digested model proteins: ubiquitin and bovine serum albumin. We also synthesized isotopically labeled analog of 5-azoniaspiro[4.4]nonyl tag to check its applicability for comparative quantitative LC-ESI-MS analysis. The obtained results indicate the general usefulness of the 5-azoniaspiro[4.4]nonyl quaternary ammonium ionization tag for LC-ESI-MS/MS sequencing and quantification of peptides, especially for those of low abundance.


Assuntos
Peptídeos/análise , Espectrometria de Massas por Ionização por Electrospray , Espectrometria de Massas em Tandem , Sequência de Aminoácidos , Cromatografia Líquida
6.
J Pept Sci ; 21(12): 879-86, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26497644

RESUMO

The bicyclic amines in the form of cryptands, the crown ether analogs, were used in the synthesis of cryptando-peptidic conjugates with simultaneous formation of quaternary ammonium nitrogen moiety. A series of model cryptando-peptidic conjugates at the peptide N-terminus was efficiently prepared by the standard Fmoc solid phase synthesis. Tandem mass spectrometric analysis of the obtained conjugates has shown the specific fragmentation pattern during MS/MS experiment. The obtained cryptandic quaternary ammonium group undergoes the Hofmann elimination during collision-induced dissociation fragmentation followed by the ethoxyl group elimination. The presented quaternization of cryptands by iodoacetylated peptides is relatively easy and compatible with standard solid-phase peptide synthesis. Additionally, the applicability of such peptide derivatives and their isotopologues selectively deuterated at the α-carbon in the quantitative LC-MS analysis was analyzed.


Assuntos
Éteres Cíclicos/química , Peptídeos/síntese química , Bases de Schiff/química , Técnicas de Síntese em Fase Sólida/métodos , Aminas/química , Estrutura Molecular , Peptídeos/química , Compostos de Amônio Quaternário/química , Espectrometria de Massas em Tandem/métodos
7.
J Mass Spectrom ; 49(6): 529-36, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24913405

RESUMO

Recently, we developed a selective and efficient method of hydrogen-deuterium exchange (HDX) at the α-carbon (α-C) of sarcosine residue (N-methylglycine) in model peptides [Bachor et al. J. Mass Spectrom. 2014, 49, 43]. Here, we report the influence of quaternary ammonium (QA) group on HDX at the α-C of sarcosine and N-methylalanine in peptides. The obtained results suggest a significant acceleration of the HDX in sarcosine residue caused by the presence of QA. The effect depends on the distance between the sarcosine residue and QA moiety. The deuterons, introduced at α-C, are resistant to the back-exchange in acidic aqueous solution. The collision induced dissociation of the deuterium-labeled analogs of QA-tagged oligosarcosine peptides without mobile hydrogen revealed the mobilization of the hydrogens localized at α-C of sarcosine residue.


Assuntos
Alanina/química , Carbono/química , Medição da Troca de Deutério/métodos , Peptídeos/química , Compostos de Amônio Quaternário/química , Sarcosina/química , Alanina/análogos & derivados , Íons/análise , Íons/química , Peptídeos/análise , Prótons
8.
J Am Soc Mass Spectrom ; 25(6): 966-76, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24687577

RESUMO

We present new tags based on the derivatives of phenylboronic acid and apply them for the selective detection of sugars and peptide-sugar conjugates in mass spectrometry. We investigated the binding of phenylboronic acid and its quaternary ammonium salt (QAS) derivatives to carbohydrates and peptide-derived Amadori products by HR-MS and MS/MS experiments. The formation of complexes between sugar or sugar-peptide conjugates and synthetic tags was confirmed on the basis of the unique isotopic distribution resulting from the presence of boron atom. Moreover, incorporation of a quaternary ammonium salt dramatically improved the efficiency of ionization in mass spectrometry. It was found that the formation of a complex with phenylboronic acid stabilizes the sugar moiety in glycated peptides, resulting in simplification of the fragmentation pattern of peptide-derived Amadori products. The obtained results suggest that derivatization of phenylboronic acid as QAS is a promising method for sensitive ESI-MS detection of carbohydrates and their conjugates formed by non-enzymatic glycation or glycosylation.


Assuntos
Ácidos Borônicos/química , Carboidratos/análise , Peptídeos/análise , Compostos de Amônio Quaternário/química , Espectrometria de Massas por Ionização por Electrospray/métodos , Carboidratos/química , Peptídeos/química
9.
Peptides ; 55: 32-40, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24525024

RESUMO

The cyclization of linear analogs based on endomorphin-2 structure, Tyr/Dmt-d-Lys-Phe-Phe-Asp-NH2 and Tyr/Dmt-d-Cys-Phe-Phe-Cys-NH2 (where Dmt=2',6'-dimethyltyrosine), resulting in obtaining lactam or disulfide derivatives, was studied using liquid chromatography combined with on-line mass spectrometry (LC-MS) and tandem mass spectrometry (LC-MS/MS). In case of cyclization via an amide bond, the formation of the cyclic monomers, cyclic but not linear dimers and even traces of cyclic trimers was observed. Disulfide bridge containing peptides was obtained by the solid-phase synthesis of the linear sequences, followed by either in-solution or on-resin cyclization. In case of the in-solution cyclization, the expected cyclic monomers were the only products. When oxidation of the cysteine residues was performed when the peptides were still on the resin, cyclic monomer and two cyclodimers, parallel and antiparallel, were found. Digestion of the isolated cyclodimers with α-chymotrypsin allowed for their unambiguous identification. The comparison of the cyclic monomer/dimer ratios for analogs with Tyr versus Dmt in position 1 revealed that the presence of the exocyclic Dmt favored formation of the cyclic monomer, most likely due to the increased steric bulk of this amino acid side-chain as compared with Tyr.


Assuntos
Entorpecentes/síntese química , Oligopeptídeos/química , Peptídeos Cíclicos/síntese química , Sequência de Aminoácidos , Cromatografia Líquida de Alta Pressão , Ciclização , Cistina/química , Técnicas de Síntese em Fase Sólida , Espectrometria de Massas por Ionização por Electrospray , Espectrometria de Massas em Tandem
10.
J Mass Spectrom ; 49(1): 43-9, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24446262

RESUMO

Hydrogens connected to α-carbon (α-C) of amino acid residues are usually resistant to hydrogen-deuterium exchange (HDX) unless reaction conditions promote racemization. Although N-methylglycine (sarcosine) residue has been found in biologically active peptide such as cyclosporine, to the best of our knowledge, the HDX of α-C protons of this residue was not explored yet. Here, we presented a new and efficient methodology of α-C deuteration in sarcosine residues under basic aqueous conditions. The deuterons, introduced at α-C atom, do not undergo back-exchange in acidic aqueous solution. The electrospray ionization-MS and MS/MS experiments on proposed model peptides confirmed the HDX at α-C and revealed the unexpected hydrogen scrambling in sarcosine-containing peptides. Although the observed HDX of α-C protons is only successful in N-acylglycine when the amide possesses a certain degree of alkylation, it offers a new approach to the analysis of sarcosine-containing peptides such as cyclosporine.


Assuntos
Carbono/química , Deutério/química , Glicina/química , Peptídeos/química , Medição da Troca de Deutério , Prótons , Espectrometria de Massas por Ionização por Electrospray/métodos , Espectrometria de Massas em Tandem/métodos
11.
Mol Divers ; 17(3): 605-11, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23690169

RESUMO

A straightforward cleavage method for N- acylated peptides based on the phenylthiohydantoin (PTH) formation is presented. The procedure could be applied to acid-stable resins, such as TentaGel HL-NH[Formula: see text]. We designed a cleavable linker that consists of a lysine residue with the [Formula: see text]-amino group blocked by Boc, whereas the [Formula: see text]-amino group is used for peptide synthesis. After the peptide assembly is completed, the protecting groups in peptide side chains are removed using trifluoroacetic acid, thus liberating also the [Formula: see text]-amino group of the lysine in the linker. Then the reaction with phenyl isothiocyanate followed by acidolysis causes an efficient peptide release from the resin as a stable PTH derivative. Furthermore, the application of a fixed charge tag in the form of 2-(4-aza-1-azoniabicyclo[2.2.2]octylammonium)acetyl group increases ionization efficiency and reduces the detection limit, allowing ESI-MS/MS sequencing of peptides in the subfemtomolar range. The proposed strategy is compatible with standard conditions during one-bead-one-compound peptide library synthesis. The applicability of the developed strategy in combinatorial chemistry was confirmed using a small training library of [Formula: see text]-chymotrypsin substrates.


Assuntos
Peptídeos/química , Feniltioidantoína/química , Análise de Sequência de Proteína/métodos , Sequência de Aminoácidos , Técnicas de Química Combinatória , Biblioteca de Peptídeos , Espectrometria de Massas em Tandem
12.
J Am Soc Mass Spectrom ; 24(6): 846-56, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23609183

RESUMO

The fragmentation of peptides containing quaternary ammonium group, but lacking easily mobilizable protons, was examined with the aid of deuterium-labeled analogs and quantum-chemical modeling. The fragmentation of oligoproline containing quaternary ammonium group involves the mobilization of hydrogens localized at α- and γ- or δ-carbon atoms in the pyrrolidine ring of proline. The study of the dissociation pattern highlights the unusual proline residue behavior during MS/MS experiments of peptides.


Assuntos
Oligopeptídeos/química , Prolina/química , Deutério , Gases/química , Íons/química , Modelos Moleculares , Prótons , Espectrometria de Massas em Tandem
13.
J Am Soc Mass Spectrom ; 23(6): 1024-8, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22403022

RESUMO

Derivatization of peptides as quaternary ammonium salts (QAS) is a known method for sensitive detection by electrospray ionization tandem mass spectrometry. Hydrogens at α-carbon atom in N,N,N-trialkylglycine residue can be easily exchanged by deuterons. The exchange reaction is base-catalyzed and is dramatically slow at lower pH. Introduced deuterons are stable in acidic aqueous solution and are not back-exchanged during LC-MS analysis. Increased ionization efficiency, provided by the fixed positive charge on QAS group, as well as the deuterium labeling, enables the analysis of trace amounts of peptides.


Assuntos
Carbono/química , Medição da Troca de Deutério/métodos , Deutério/química , Glicina/análogos & derivados , Compostos de Amônio Quaternário/química , Betaína/química , Cromatografia Líquida , Glicina/química , Concentração de Íons de Hidrogênio , Marcação por Isótopo , Espectrometria de Massas/métodos , Peptídeos/química
14.
Anal Biochem ; 419(2): 81-7, 2011 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-21933658

RESUMO

A nonenzymatic reaction of reducing sugars with the free amino group located at the N terminus of the polypeptide chain or in the lysine side chain results in glycation of proteins. The fragments of glycated proteins obtained by enzymatic hydrolysis could be considered as the biomarkers of both the aging process and diabetes mellitus. Here we propose a new method for the identification of peptide-derived Amadori products in the enzymatic digest of glycated proteins. The products of enzymatic hydrolysis of the model protein ubiquitin were incubated with H(2)(18)O under microwave activation. We observed that at these conditions the Amadori compounds selectively exchange one oxygen atom in the hexose moiety. The characteristic isotopic pattern of Amadori products treated with H(2)(18)O allows fast and convenient identification of this group of compounds, whereas nonglycated peptides are not susceptible to isotopic exchange.


Assuntos
Glicopeptídeos/química , Marcação por Isótopo/métodos , Oxigênio/metabolismo , Sequência de Aminoácidos , Animais , Bovinos , Glicopeptídeos/metabolismo , Glicosilação , Hidrólise , Micro-Ondas , Dados de Sequência Molecular , Isótopos de Oxigênio , Pepsina A/química , Pepsina A/metabolismo , Espectrometria de Massas por Ionização por Electrospray , Ubiquitina/química , Ubiquitina/metabolismo
15.
Amino Acids ; 40(3): 923-32, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20734213

RESUMO

Protein glycation is often a cause of diabetes-associated complications. The isotopically labeled peptide-derived Amadori products may serve as standards for quantitative determination of the glycated proteins. In this paper, we discussed various approaches to the synthesis of Amadori products labeled selectively with stable isotopes (2)H, (13)C and (18)O.


Assuntos
Peptídeos/química , Glicosilação , Marcação por Isótopo , Peptídeos/síntese química
16.
Anal Biochem ; 400(2): 237-43, 2010 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-20156417

RESUMO

The products of nonenzymatic glycation of proteins are formed in a chemical reaction between reducing sugars and the free amino group located either at the N terminus of the polypeptide chain or in the lysine side chain. Glycated proteins and their fragments could be used as markers of the aging process as well as diabetes mellitus and Alzheimer's disease, making them an object of interest in clinical chemistry. In this article, we propose a new method for the identification of peptide-derived Amadori products in the mixtures obtained by enzymatic hydrolysis of glycated proteins. Two proteins, ubiquitin and human serum albumin (HSA), were modified with an equimolar mixture of glucose and [(13)C(6)]glucose and were subjected to enzymatic hydrolysis. The obtained enzymatic digests were analyzed by high-resolution mass spectrometry (HRMS), and the peptide-derived Amadori products were identified on the basis of specific isotopic patterns resulting from (13)C substitution. The number of glycated peptides in the digest of HSA detected by our procedure was in agreement with the data recently reported in the literature.


Assuntos
Produtos Finais de Glicação Avançada/química , Proteínas/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Sequência de Aminoácidos , Isótopos de Carbono , Glucose/química , Humanos , Marcação por Isótopo , Dados de Sequência Molecular , Peptídeos/análise , Albumina Sérica/química , Ubiquitina/química
17.
J Pept Sci ; 16(1): 31-9, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19904803

RESUMO

Microwave-assisted (MW) reactions are of special interest to the chemical community due to faster reaction times, cleaner reactions and higher product yields. The adaptation of MW to solid phase peptide synthesis resulted in spectacular syntheses of difficult peptides. In the case of Merrifield support, used frequently in synthesis of special peptides, the conditions used in product cleavage are not compatible with off-resin monitoring of the reaction progress. The application of MW irradiation in product removal from Merrifield resin using trifluoroacetic acid (TFA) was investigated using model tetrapeptides and the effects were compared with standard trifluoromethanesulphonic acid (TFMSA) cleavage using elemental analysis as well as chromatographic (HPLC) and spectroscopic (IR) methods. The deprotection of benzyloxycarbonyl and benzyl groups in synthetic bioactive peptides was analyzed using LC-MS and MS/MS experiments. In a 5 min microwave-assisted TFA reaction at low temperature, the majority of product is released from the resin, making the analytical scale MW-assisted procedure a method of choice in monitoring the reactions carried out on Merrifield resin due to the short reaction time and compatibility with HPLC and ESI-MS conditions.


Assuntos
Micro-Ondas , Peptídeos/química , Poliestirenos/química , Ácido Trifluoracético/química , Sequência de Aminoácidos , Cromatografia Líquida de Alta Pressão , Espectrofotometria Infravermelho , Espectrometria de Massas em Tandem
18.
Rapid Commun Mass Spectrom ; 23(24): 4038-46, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19924780

RESUMO

Hexose-modified peptides, products of the enzymatic hydrolysis of glycated proteins, could be used as markers of diabetes mellitus, the aging process and other diseases. The main difficulty in this approach is the detection of glycated peptides in the complex mixtures of compounds. In this study we investigated the formation of borate complexes of the peptide-derived Amadori products by high-resolution mass spectrometry (HRMS) and tandem mass spectrometry (MS/MS) experiments. It was found that the formation of a complex with the borate ion stabilizes the sugar moiety, resulting in the simplification of the fragmentation patterns of peptide-derived Amadori products. The level of dehydration, as well as the elimination of formaldehyde from the precursor ions of borate complexes, was lower as compared to the free peptide. On the other hand the intensity of the b- and y-type ions for borate complexes is significantly higher in comparison to the free peptide-derived Amadori product. Moreover, the elimination of a whole hexose moiety was not detected in the examined peptides.


Assuntos
Boratos/química , Íons/química , Peptídeos/química , Espectrometria de Massas por Ionização por Electrospray/métodos , Animais , Bovinos , Glicosilação , Mapeamento de Peptídeos , Albumina Sérica/química
19.
J Pept Sci ; 15(4): 296-304, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19206073

RESUMO

Modulation of protein-protein interactions involved in the immune system by using small molecular mimics of the contact interfaces may lead to the blockage of the autoimmune response and the development of drugs for immunotherapy. The nonpolymorphic beta-regions, exposed to the microenvironment, of the modeled HLA-DQ7, which is genetically linked to autoimmune diseases, were determined. Peptides 132-141 and 58-67, located at the beta(1) and beta(2) domains of HLA-DQ7, respectively, were tested for their involvement in the interactions with CD4(+) T lymphocytes. Linear, cyclic, and dimeric analogs that mimic the exposed surfaces of HLA-DQ7 were designed and synthesized. Their immunosuppressory activities, found in the secondary, humoral immune response to sheep erythrocytes (SRBC) in mice in vitro, ranged from 11% to 53%. The significance of the total charge of the peptides, the pattern of the hydrogen bonding, and the presence of secondary structure were investigated in relation to the immunomodulatory effect of the peptides. Two dimeric analogs of the HLA-DQ7 58-67 fragment, consisting of the two monomers covalently linked by a polyethylene glycol (PEG) spacer, able to mimic the superdimers, were also synthesized and studied. As the 58-67 segment is located at the beta(1) region of HLA-DQ7, close to the major histocompatibility complex (MHC) groove, one may assume that the 58-67 peptide could accommodate the association between T-cell receptor (TCR) and human leukocyte antigen (HLA) by activating a co-stimulatory molecule of the TCR/HLA interaction. This hypothesis is supported by the confocal laser image of the fluorescein-labeled 58-67 peptide and by the fact that it is an immunostimulator at low concentration.


Assuntos
Antígenos HLA-DQ/química , Fatores Imunológicos/síntese química , Sequência de Aminoácidos , Animais , Linhagem Celular , Feminino , Antígenos HLA-DQ/imunologia , Antígenos HLA-DQ/farmacologia , Humanos , Fatores Imunológicos/química , Fatores Imunológicos/farmacologia , Linfócitos/efeitos dos fármacos , Linfócitos/imunologia , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos CBA , Modelos Moleculares , Oligopeptídeos/síntese química , Oligopeptídeos/química , Oligopeptídeos/imunologia , Oligopeptídeos/farmacologia , Fragmentos de Peptídeos/síntese química , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/imunologia , Fragmentos de Peptídeos/farmacologia , Conformação Proteica , Espectrometria de Massas por Ionização por Electrospray
20.
Amino Acids ; 36(2): 309-15, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18392772

RESUMO

A direct solid-phase synthesis of a series of substituted benzimidazole-containing peptides is described. The method involves on-resin formation of new amino acids containing benzimidazole derivatives in the side chain. The heterocycle conjugates were obtained by reaction between aldehydes and peptides containing beta-(3,4-diaminophenyl)alanine residue, immobilized on a polymeric solid support.


Assuntos
Alanina/química , Bisbenzimidazol/química , Peptídeos/síntese química
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