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1.
Int J Mol Sci ; 23(19)2022 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-36232575

RESUMO

In recent years, several studies aimed to investigate the metabolic effects of non-functioning or absent cyclophilin D (CypD), a crucial regulatory component of mitochondrial permeability transition pores. It has been reported that the lack of CypD affects glucose and lipid metabolism. However, the findings are controversial regarding the metabolic pathways involved, and most reports describe the effect of a high-fat diet on metabolism. We performed a lipidomic analysis of plasma and liver samples of CypD-/- and wild-type (WT) mice to reveal the lipid-specific alterations resulting from the absence of CypD. In the CypD-/- mice compared to the WT animals, we found a significant change in 52% and 47% of the measured 225 and 201 lipid species in liver and plasma samples, respectively. The higher total lipid content detected in these tissues was not accompanied by abdominal fat accumulation assessed by nuclear magnetic resonance imaging. We also documented characteristic changes in the lipid composition of the liver and plasma as a result of CypD ablation with the relative increase in polyunsaturated membrane lipid species. In addition, we did not observe remarkable differences in the lipid distribution of hepatocytes using histochemistry, but we found characteristic changes in the hepatocyte ultrastructure in CypD-/- animals using electron microscopy. Our results highlight the possible long-term effects of CypD inhibition as a novel therapeutic consideration for various diseases.


Assuntos
Lipidômica , Proteínas de Transporte da Membrana Mitocondrial , Animais , Peptidil-Prolil Isomerase F , Ciclofilinas/genética , Ciclofilinas/metabolismo , Glucose , Fígado/metabolismo , Lipídeos de Membrana , Camundongos , Camundongos Knockout , Proteínas de Transporte da Membrana Mitocondrial/metabolismo
2.
Molecules ; 27(15)2022 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-35956776

RESUMO

Carotenoid succinates were synthesized from hydroxy carotenoids and were coupled to a commercially available derivative of melatonin via amide bond for producing more powerful anti-oxidants and yet new hybrid lipophilic bifunctional molecules with additional therapeutic effects. The coupling reactions produced conjugates in acceptable to good yields. Succinylation increased the water solubility of the carotenoids, while the conjugation with melatonin resulted in more lipophilic derivatives. The conjugates showed self-assembly in aqueous medium and yielded relatively stable colloidal solutions in phosphate-buffered saline. Antioxidant behavior was measured with ABTS and the FRAP methods for the carotenoids, the carotenoid succinates, and the conjugates with melatonin. A strong dependence on the quality of the solvent was observed. TEAC values of the new derivatives in phosphate-buffered saline were found to be comparable to or higher than those of parent carotenoids, however, synergism was observed only in FRAP assays.


Assuntos
Antioxidantes , Melatonina , Antioxidantes/química , Carotenoides/química , Fosfatos , Succinatos
3.
Cells ; 10(6)2021 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-34071596

RESUMO

Our dream of defeating the processes of aging has occupied the curious and has challenged scientists globally for hundreds of years. The history is long, and sadly, the solution is still elusive. Our endeavors to reverse the magnitude of damaging cellular and molecular alterations resulted in only a few, yet significant advancements. Furthermore, as our lifespan increases, physicians are facing more mind-bending questions in their routine practice than ever before. Although the ultimate goal is to successfully treat the body as a whole, steps towards regenerating individual organs are even considered significant. As our initial approach to enhance the endogenous restorative capacity by delivering exogenous progenitor cells appears limited, we propose, utilizing small molecules critical during embryonic development may prove to be a powerful tool to increase regeneration and to reverse the processes associated with aging. In this review, we introduce Thymosin beta-4, a 43aa secreted peptide fulfilling our hopes and capable of numerous regenerative achievements via systemic administration in the heart. Observing the broad capacity of this small, secreted peptide, we believe it is not the only molecule which nature conceals to our benefit. Hence, the discovery and postnatal administration of developmentally relevant agents along with other approaches may result in reversing the aging process.


Assuntos
Envelhecimento/efeitos dos fármacos , Regeneração/efeitos dos fármacos , Timosina/farmacologia , Animais , Desenvolvimento Embrionário/efeitos dos fármacos , Humanos
4.
Molecules ; 26(2)2021 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-33477841

RESUMO

Melilotus officinalis is known to contain several types of secondary metabolites. In contrast, the carotenoid composition of this medicinal plant has not been investigated, although it may also contribute to the biological activities of the drug, such as anti-inflammatory effects. Therefore, this study focuses on the isolation and identification of carotenoids from Meliloti herba and on the effect of isolated (all-E)-lutein 5,6-epoxide on primary sensory neurons and macrophages involved in nociception, as well as neurogenic and non-neurogenic inflammatory processes. The composition of the plant extracts was analyzed by high performance liquid chromatography (HPLC). The main carotenoid was isolated by column liquid chromatography (CLC) and identified by MS and NMR. The effect of water-soluble lutein 5,6-epoxide-RAMEB (randomly methylated-ß-cyclodextrin) was investigated on Ca2+-influx in rat primary sensory neurons induced by the activation of the transient receptor potential ankyrin 1 receptor agonist to mustard-oil and on endotoxin-induced IL-1ß release from isolated mouse peritoneal macrophages. (all-E)-Lutein 5,6-epoxide significantly decreased the percent of responsive primary sensory neurons compared to the vehicle-treated stimulated control. Furthermore, endotoxin-evoked IL-1ß release from macrophages was significantly decreased by 100 µM lutein 5,6-epoxide compared to the vehicle-treated control. The water-soluble form of lutein 5,6-epoxide-RAMEB decreases the activation of primary sensory neurons and macrophages, which opens perspectives for its analgesic and anti-inflammatory applications.


Assuntos
Luteína/análogos & derivados , Macrófagos/efeitos dos fármacos , Melilotus/química , Células Receptoras Sensoriais/efeitos dos fármacos , Animais , Luteína/análise , Luteína/isolamento & purificação , Luteína/farmacologia , Macrófagos/citologia , Camundongos , Ratos , Células Receptoras Sensoriais/citologia
5.
Int J Mol Sci ; 21(19)2020 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-33027919

RESUMO

Previously, we showed that desethylamiodarone (DEA), a major metabolite of the widely used antiarrhythmic drug amiodarone, has direct mitochondrial effects. We hypothesized that these effects account for its observed cytotoxic properties and ability to limit in vivo metastasis. Accordingly, we examined DEA's rapid (3-12 h) cytotoxicity and its early (3-6 h) effects on various mitochondrial processes in B16F10 melanoma cells. DEA did not affect cellular oxygen radical formation, as determined using two fluorescent dyes. However, it did decrease the mitochondrial transmembrane potential, as assessed by JC-1 dye and fluorescence microscopy. It also induced mitochondrial fragmentation, as visualized by confocal fluorescence microscopy. DEA decreased maximal respiration, ATP production, coupling efficiency, glycolysis, and non-mitochondrial oxygen consumption measured by a Seahorse cellular energy metabolism analyzer. In addition, it induced a cyclosporine A-independent mitochondrial permeability transition, as determined by Co2+-mediated calcein fluorescence quenching measured using a high-content imaging system. DEA also caused outer mitochondrial membrane permeabilization, as assessed by the immunoblot analysis of cytochrome C, apoptosis inducing factor, Akt, phospho-Akt, Bad, and phospho-Bad. All of these data supported our initial hypothesis.


Assuntos
Amiodarona/análogos & derivados , Proliferação de Células/efeitos dos fármacos , Melanoma Experimental/tratamento farmacológico , Mitocôndrias/genética , Amiodarona/farmacologia , Animais , Apoptose/efeitos dos fármacos , Fator de Indução de Apoptose , Citocromos c/genética , Citostáticos/farmacologia , Metabolismo Energético/efeitos dos fármacos , Humanos , Pulmão/metabolismo , Pulmão/patologia , Melanoma Experimental/genética , Melanoma Experimental/patologia , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos , Mitocôndrias/efeitos dos fármacos , Consumo de Oxigênio/efeitos dos fármacos , Permeabilidade/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo
6.
Molecules ; 25(3)2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32024181

RESUMO

Flavonoids and carotenoids possess beneficial physiological effects, such as high antioxidant capacity, anticarcinogenic, immunomodulatory, and anti-inflammatory properties, as well as protective effects against UV light. The covalent coupling of hydrophobic carotenoids with hydrophilic flavonoids, such as daidzein and chrysin, was achieved, resulting in new amphipathic structures. 7-Azidohexyl ethers of daidzein and chrysin were prepared in five steps, and their azide-alkyne [4 + 2] cycloaddition with pentynoates of 8'-apo-ß-carotenol, zeaxanthin, and capsanthin afforded carotenoid-flavonoid conjugates. The trolox-equivalent antioxidant capacity against ABTS•+ radical cation and self-assembly of the final products were examined. The 1:1 flavonoid-carotenoid hybrids generally showed higher antioxidant activity than their parent flavonoids but lower than that of the corresponding carotenoids. The diflavonoid hybrids of zeaxanthin and capsanthin, however, were found to exhibit a synergistic enhancement in antioxidant capacities. ECD (electronic circular dichroism) and UV-vis analysis of zeaxanthin-flavonoid conjugates revealed that they form different optically active J-aggregates in acetone/water and tetrahydrofuran/water mixtures depending on the solvent ratio and type of the applied aprotic polar solvent, while the capsanthin derivatives showed no self-assembly. The zeaxanthin bis-triazole conjugates with daidzein and with chrysin, differing only in the position of a phenolic hydroxyl group, showed significantly different aggregation profile upon the addition of water.


Assuntos
Antioxidantes/química , Carotenoides/química , Técnicas de Química Sintética , Flavonoides/química , Análise de Variância , Antioxidantes/síntese química , Estrutura Molecular , Análise Espectral
7.
J Org Chem ; 82(1): 390-396, 2017 01 06.
Artigo em Inglês | MEDLINE | ID: mdl-27983839

RESUMO

Palladium-catalyzed aminocarbonylation reactions have been used to directly convert a tetraiodocavitand intermediate into the corresponding carboxamides and 2-ketocarboxamides. When complex mixtures of the amine reactants are employed in competition experiments using polar solvents, such as DMF, no "mixed" products possessing structurally different amide fragments are detected either by 1H or 13C NMR. Only highly symmetrical cavitands are sorted out of a large number of potentially feasible products, which represents a rare example of intramolecular, narcissistic self-sorting. Our experimental results along with thermodynamic energy analysis suggest that the observed self-sorting is a symmetry-driven, kinetically controlled process.

8.
Environ Sci Pollut Res Int ; 23(12): 11630-8, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26936475

RESUMO

17ß-Estradiol (E2) and 17α-ethinyl estradiol (EE2), which are environmental estrogens, have been determined with LC-MS in freshwater. Their sensitive analysis needs derivatization and therefore is very hard to achieve in multiresidue screening. We analyzed samples from all the large and some small rivers (River Danube, Drava, Mur, Sava, Tisza, and Zala) of the Carpathian Basin and from Lake Balaton. Freshwater was extracted on solid phase and derivatized using dansyl chloride. Separation was performed on a Kinetex XB-C18 column. Detection was achieved with a benchtop orbitrap mass spectrometer using targeted MS analysis for quantification. Limits of quantification were 0.05 ng/L (MS1) and 0.1 ng/L (MS/MS) for E2, and 0.001 ng/L (MS1) and 0.2 ng/L (MS/MS) for EE2. River samples contained n.d.-5.2 ng/L E2 and n.d.-0.68 ng/L EE2. Average levels of E2 and EE2 were 0.61 and 0.084 ng/L, respectively, in rivers, water courses, and Lake Balaton together, but not counting city canal water. EE2 was less abundant, but it was still present in almost all of the samples. In beach water samples from Lake Balaton, we measured 0.076-0.233 E2 and n.d.-0.133 EE2. A relative high amount of EE2 was found in river Zala (0.68 ng/L) and in Hévíz-Páhoki canal (0.52 ng/L), which are both in the catchment area of Lake Balaton (Hungary).


Assuntos
Estradiol/análise , Estrogênios/análise , Etinilestradiol/análise , Rios/química , Poluentes Químicos da Água/análise , Cromatografia Líquida , Monitoramento Ambiental , Hungria , Lagos/química , Espectrometria de Massas em Tandem
9.
Clin Oral Investig ; 17(7): 1709-17, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23103960

RESUMO

OBJECTIVES: Several theories have been proposed regarding the genesis of sialoliths, including the organic core theory, which suggests epithelial or bacterial etiology originating in the central core. Our aim was to use novel methodologies to analyze central areas (the core) of calculi from sialolithiasis patients. MATERIALS AND METHODS: The structures of the halves of six submandibular salivary stones were analyzed by scanning electron microscopy (SEM). After structural analysis, from the other six halves, samples from the central parts of the core and peripheral parts of the core were digested with trypsin and analyzed by matrix-assisted laser desorption ionization-time of flight mass spectrometry. The peptide mass fingerprints were compared with the results of in silico digestion. RESULTS: SEM analysis of the sialoliths showed that organic structures (collagen/fibrous-like structures, bacterial fragments) were visible only outside of the core in the concentric layers of external areas, but not in the core area. The mass spectrometry (MS)/MS post-source decay experiments were completed from the four, most intense signals observed in the MS spectrum and human defensin was proven to be present in three of the examined samples, originated from the peripheral region of three cores. CONCLUSIONS: Although proteomic analysis demonstrated defensin protein in the peripheral region of the core in three sialoliths, SEM failed to prove organic structures in the core. CLINICAL RELEVANCE: New investigation modalities still cannot prove organic structures in the core, henceforward challenging the organic core theory.


Assuntos
Microscopia Eletrônica de Varredura , Proteômica , Cálculos das Glândulas Salivares/patologia , Cálculos das Glândulas Salivares/ultraestrutura , Glândula Submandibular/patologia , Glândula Submandibular/ultraestrutura , Humanos , Técnicas In Vitro , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
10.
Scand J Gastroenterol ; 45(12): 1440-8, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20653491

RESUMO

OBJECTIVE: Measurement of the immunoreactive urinary albumin (ir-uAlb) concentration by immunological methods was found to be an effective method to identify disease activity in Crohn's disease (CD). Recently a size-exclusion (SE) high performance liquid chromatography (HPLC) method was developed to measure both ir-uAlb and non-immunoreactive urinary albumin (total, t-uAlb). We aimed to follow-up one of our CD patients with frequent remissions and exacerbation phases comparing the changes of disease activity parameters and the concentration of ir-uAlb and t-uAlb. The surprising results led us to perform measurements in greater depth. MATERIAL AND METHODS: Concentration of ir-uAlb was measured by immunoturbidimetry (IT) and t-uAlb by SE-HPLC. Albumin peak of SE-HPLC was collected and applied to a reversed-phase (RP) HPLC and to gel-electrophoresis. Eluted peaks of RP-HPLC and identified bands of gel-electrophoresis were analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS). RESULTS: The concentration of t-uAlb was 15 times higher than that of the ir-uAlb during active state. The RP-HPLC and the gel-electrophoresis separation proved that albumin peak by size-exclusion consists of three different peaks. MALDI-TOF/MS measurements identified α1-acid-glycoprotein and Zn-α2-glycoprotein as major, and albumin as minor protein. CONCLUSIONS: Peak of albumin of SE-HPLC contains a significant amount of glycoprotein during the active phase of CD, which could not be detected in remission. Urinary α1-acid-glycoprotein and/or Zn-α2-glycoprotein could be an ideal disease activity biomarker of CD.


Assuntos
Albuminúria/urina , Doença de Crohn/urina , Adulto , Biomarcadores/urina , Progressão da Doença , Humanos , Masculino
11.
J Mass Spectrom ; 45(5): 545-52, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20446313

RESUMO

In spite of the growing acceptance of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for the analysis of a wide variety of compounds, including polymers and proteins, its use in analyzing low-molecular-weight molecules (<1000 m/z) is still limited. This is mainly due to the interference of matrix molecules in the low-mass range. Here the derivatized fullerenes covalently bound to silica particles with different pore sizes are applied as thin layer for laser desorption/ionization (LDI) mass spectrometric analysis. Thus, an interference of intrinsic matrix ions can be eliminated or minimized in comparison with the state-of-the-art weak organic acid matrices. The desorption/ionization ability of the developed fullerene-silica materials depends on the applied laser power, sample preparation and pore size of the silica particles. Thus, fullerene-silica serves as an LDI support for mass spectrometric analysis of molecules (<1500 Da). The performance of the fullerene-silica is demonstrated by the mass analysis of variety of small molecules such as carbohydrates, amino acids, peptides, phospholipids and drugs.


Assuntos
Fulerenos/química , Dióxido de Silício/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Aminoácidos/química , Carboidratos/química , Ácido Desoxicólico/química , Peso Molecular , Fosfolipídeos/química
12.
Anal Biochem ; 393(1): 8-22, 2009 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-19524544

RESUMO

Amadori peptides were enriched using boronate affinity tips and measured by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS). As demonstrated by electrochemical measurements, the tips show the highest binding efficiency for glucose at pH 8.2 employing ammonium chloride/ammonia buffer with ionic strength of 150 mM, exceeding taurine buffer at the same concentration. The bound constituents were released by sorbitol and formic acid. It was also demonstrated that elution with sorbitol at 1.2 M is superior to acidic media. Comparison of results was based on the numbers of detected peptides and their glycated sites. Using sorbitol for elution requires desalting prior to analysis. Therefore, three different sorbents were tested: fullerene-derivatized silica, ZipTip (C18), and C18 silica. Fullerene-derivatized silica and ZipTip showed the same performance regarding the numbers of glycated peptides, and sites were better than C18 silica. The elaborated off-line method was compared with liquid chromatography-tandem mass spectrometry (LC-MS/MS) measurements, by which considerable less modified peptides were detected. Affinity tips used under optimized conditions were tested for the analysis of human serum albumin (HSA) from sera of healthy and diabetic individuals. A peptide with a mass of 1783.9 Da could be detected only in samples of diabetic patients and, therefore, could be a very interesting biomarker candidate.


Assuntos
Cromatografia de Afinidade/métodos , Glicopeptídeos/química , Glicopeptídeos/isolamento & purificação , Glicoproteínas/química , Peptídeos/isolamento & purificação , Ácidos Borônicos/química , Cromatografia de Afinidade/instrumentação , Humanos , Estrutura Molecular , Peptídeos/química , Ribonuclease Pancreático/análise , Albumina Sérica/análise
13.
J Sep Sci ; 32(2): 295-308, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19156633

RESUMO

SPE plays a crucial role in bioanalytical research. In the present work a novel fullerene(C60)-derivatised silica material is compared with octadecyl(C18) - and triaconthyl(C30)-silicas regarding recoveries of peptides and sequence coverage of HSA and fibrinogen digests. C30- and C60(30 nm)-SPE materials were found to be the two most prominent SPE materials. At low peptide concentrations C60-material prepared from a silica gel with a pore size of 30 nm has proven to be the best material with regards to recoveries. By increasing the amount of loaded peptides recoveries decrease due to its relative low binding capacity in contrast to C30-silica particles, showing no changes. The best sequence coverages of Aalpha- and Bbeta-chains of 20 pmol fibrinogen digest can also be achieved using these two SPE materials, C60 (30 nm) demonstrates an outstanding value of sequence coverage (62.15%) achieved for the gamma-chain. After nonenzymatic glycation the digests of fibrinogen and HSA were also separated. This makes the detection of a considerably higher number of glycated peptides possible compared to the unfractionated digests and the use of boronate affinity chromatography in the case of fibrinogen. For HSA, ten new sites of glycation at lysine and arginine residues have been explored. Using the detailed SPE/off-line MALDI method the glycation sites on fibrinogen are first described in this paper.


Assuntos
Fibrinogênio/análise , Fulerenos/química , Fragmentos de Peptídeos/análise , Albumina Sérica/análise , Dióxido de Silício/química , Extração em Fase Sólida/métodos , Tripsina/metabolismo , Ácidos Borônicos , Cromatografia de Afinidade , Fibrinogênio/metabolismo , Glicosilação , Humanos , Fragmentos de Peptídeos/química , Albumina Sérica/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
14.
Electrophoresis ; 28(14): 2345-50, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17476715

RESUMO

Using the molecular imprinting approach, we have shown that polyacrylamide-based artificial antibodies against human and bovine hemoglobin have a very high selectivity, as revealed by the free-zone electrophoresis in a revolving capillary. By the same technique we have previously synthesized gel antibodies not only against proteins but also against viruses and bacteria. The synthesis is thus universal, i.e., it has the great advantage of not requiring a modification - or only a slight one - for each particular antigen. The combination synthesis of artificial gel antibodies and electrophoretic analysis reveals small discrepancies in shape and chemical composition not only of proteins, as shown here and in paper Ia, but also of viruses and bacteria, to be illustrated in papers II and III in this series. Upon rehydration, the freeze-dried gel antibodies, selective for human hemoglobin, regain their selectivity. The gel antibodies can repeatedly be used following the removal of the antigen (protein in this study) from the complex gel antibody/antigen by an SDS washing or an enzymatic degradation.


Assuntos
Resinas Acrílicas/síntese química , Anticorpos/química , Eletroforese/métodos , Hemoglobinas/imunologia , Animais , Bactérias/química , Bactérias/imunologia , Bovinos , Géis , Hemoglobinas/química , Humanos , Proteínas/química , Proteínas/imunologia , Vírus/química , Vírus/imunologia
15.
Electrophoresis ; 27(23): 4682-7, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17136716

RESUMO

Artificial antibodies in the form of gel granules were synthesized from the monomers acrylamide and N,N'-methylenebisacrylamide by the imprinting method in the presence of Echerichia coli bacteria as template. The electrophoretic migration velocities of the gel antibodies (i) saturated with the antigen (Escherichia coli MRE-600), (ii) freed of the antigen, and (iii) resaturated with bacteria, were determinated by electrophoresis in a rotating narrow-bore tube of 245 mm length and the 2.5 and 9.6 mm inner and outer diameters, respectively. Removal of bacteria from the gel antibodies was made by treatment with enzymes, followed by washing with SDS and buffer. Gel granules becoming charged by adsorption of bacteria move in an electrical field. We obtained a significant selectivity of gel antibodies for E. coli MRE-600, since the granules did not interact with Lactococcus lactis; and when E. coli BL21 bacteria were added to the gels selective for E. coli MRE-600, a significant difference in the migration rate of the complexes formed with the two strains was observed indicating the ability of differentiation between the two strains. The gel antibodies can be used repeatedly. The new imprinting method for the synthesis of artificial gel antibodies against bioparticles described herein, and the classical electrophoretic analysis technique employed, thus represent - when combined - a new approach to distinguish between different types and strains of bacteria. The application area can certainly be extended to cover other classes of cells.


Assuntos
Acrilamida/química , Acrilamidas/química , Anticorpos Antibacterianos/química , Anticorpos Antibacterianos/isolamento & purificação , Eletroforese/métodos , Antígenos de Bactérias/química , Antígenos de Bactérias/imunologia , Soluções Tampão , Escherichia coli/química , Escherichia coli/imunologia , Géis/química , Estrutura Molecular , Proteínas/química , Vírus/química
16.
J Mol Recognit ; 19(4): 270-4, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16703571

RESUMO

Studies of molecular recognition of chiral compounds by proteins are of importance from many points of view. The biological role of proteins in their interaction with small molecules is of fundamental interest and can be used in many different fields, for instance for in vitro analysis of optically active compounds. Studies in these areas need a detailed study of the interaction sites on the protein surface and the relationship between chemical structure and the complex formation ability of small molecules, such as drugs. The electrophoretic migration of charged compounds through a protein zone may provide information about the surface properties of the macromolecule in the interaction site. The interaction of human serum transferrin with tryptophan-methyl- (TME), ethyl- (TEE) and butyl-esters (TBE) has been investigated by capillary electrophoresis (CE) and model calculations. Differences in the separation of tryptophan derivatives were obtained by varying experimental parameters such as, pH, ionic strength of background electrolyte and the length of transferrin zone. Limited separation of the enantiomer pairs were observed at pH 5 and 7 with a maximum resolution at pH 6. The size of the ligands coupled to the chiral centre has importance in stereoselective recognition; however, a direct comparison of resolution different in same runs may lead to false conclusion if the experimental conditions are not comparable. With a careful evaluation of the data we obtained significant differences between the resolution of the smallest enantiomer pair compared to those of tryptophan derivatives with longer alkyl chains.


Assuntos
Transferrina/química , Transferrina/metabolismo , Eletroforese Capilar , Humanos , Concentração de Íons de Hidrogênio , Estereoisomerismo , Relação Estrutura-Atividade , Triptofano/análogos & derivados , Triptofano/química , Triptofano/isolamento & purificação
17.
J Sep Sci ; 29(18): 2802-9, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17305242

RESUMO

Artificial antibodies in the form of gel granules were prepared by the molecular imprinting technique from the monomers acrylamide and N,N'-methylene-bis-acrylamide. Gel granules, freed from the selectively adsorbed protein (the antigen), are neutral and, accordingly, do not migrate in an electrical field. However, upon selective interaction with the antigen at a pH different from its pI, the granules become charged. The selectivity of the gel antibodies was studied by free zone electrophoresis in a tube with inside diameter larger than the size of the granules. Such electrophoretic analyses showed that gel antibodies against iron-free transferrin had a high selectivity for this protein, although some crossreaction took place with iron-saturated transferrin, indicating that these artificial antibodies can easily distinguish the minute differences in the 3-D structure of the transferrins. Analogously, gel antibodies against iron-saturated transferrin were highly selective for this protein with some crossreaction with iron-free transferrin. The mobilities of iron-free and iron-saturated transferrin are very similar, and, therefore, capillary free zone electrophoresis cannot distinguish between these structurally related proteins. However, significant differences in the mobilities of the selective gel granules can be observed depending on their interaction with iron-free or iron-saturated transferrin, i.e., the artificial gel antibodies may become powerful analytical tools.


Assuntos
Anticorpos/química , Bactérias/química , Proteínas/química , Transferrina/imunologia , Vírus/química
18.
J Sep Sci ; 29(18): 2810-5, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17305243

RESUMO

Artificial and highly selective antibodies (in the form of gel granules) against proteins can easily be synthesized by a simple, cost-effective imprinting technique [Liao, J.-L. et al., Chromatographia 1996, 42, 259-262]. Using the same method for synthesis of gel antibodies against viruses in combination with analysis by free zone electrophoresis in a rotating narrow bore tube we have shown that artificial gel antibodies against Semliki Forest Virus (wild type) can sense the difference between this virus and a mutant, although they differ in their chemical composition only by three amino acids in one of the three proteins on the surface of the virus particle. The reason for this extremely high resolution is explained by the fact that we use three types of selectivity: (i) shape selectivity (created by the close fit between the antigen and its imprint in the gel), (ii) bond selectivity in the contact area between the antigen and its imprint in the gel antibody, and (iii) charge selectivity, originating from slightly different structures or/and conformations of the antigens.


Assuntos
Anticorpos Antivirais/química , Eletroforese/métodos , Vírus da Floresta de Semliki/imunologia
19.
Talanta ; 69(1): 281-5, 2006 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-18970566

RESUMO

Amperometric detection combined with separation technique or with selective molecular recognition step can be very effective solving quantitative analytical tasks. When the amperometric working electrode surface needs cleaning or reactivation, pulsed amperometric technique can be the choice. Coating working electrodes with different sensitizing or protecting layer is quite common in the practice of voltammetric analysis. In these studies the behavior of coated electrodes using a simplified pulsed amperometric working program which can be named periodically interrupted amperometric (PIA) detection has been investigated. Rotating platinum, and carbon paste electrodes coated with dialysis film or porcine intestinal membrane were used in the experiments. The signal in case of electrochemical oxidation of hydrogen peroxide and ascorbic acid at convective conditions has been evaluated. The signal, obtained with conventional amperometry has been compared with signal collected with a periodically interrupted amperometric measuring program, allowing time for the diffusion to reload the diffusion layer at the electrode surface. The sensitivity and the lower limit of detection (4.5 x 10(-7)M for ascorbic acid and 2 x 10(-6)M for H2O2) proved superior in case of the periodically interrupted amperometry.

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