RESUMO
RNA aptamers are oligonucleotides, selected through Systematic Evolution of Ligands by EXponential Enrichment (SELEX), that can bind to specific target molecules with high affinity. One such molecule is the RNA aptamer that binds to a blue-fluorescent Hoechst dye that was modified with bulky t-Bu groups to prevent non-specific binding to DNA. This aptamer has potential for biosensor applications; however, limited information is available regarding its conformation, molecular interactions with the ligand, and binding mechanism. The study presented here aims to biophysically characterize the Hoechst RNA aptamer when complexed with the t-Bu Hoechst dye and to further optimize the RNA sequence by designing and synthesizing new sequence variants. Each variant aptamer-t-Bu Hoechst complex was evaluated through a combination of fluorescence emission, native polyacrylamide gel electrophoresis, fluorescence titration, and isothermal titration calorimetry experiments. The results were used to design a minimal version of the aptamer consisting of only 21 nucleotides. The performed study also describes a more efficient method for synthesizing the t-Bu Hoechst dye derivative. Understanding the biophysical properties of the t-Bu Hoechst dye-RNA complex lays the foundation for nuclear magnetic resonance spectroscopy studies and its potential development as a building block for an aptamer-based biosensor that can be used in medical, environmental or laboratory settings.
Assuntos
Aptâmeros de Nucleotídeos , Aptâmeros de Nucleotídeos/química , Corantes Fluorescentes/química , Conformação de Ácido Nucleico , Técnicas Biossensoriais/métodos , Sequência de Bases , Espectrometria de Fluorescência/métodos , Técnica de Seleção de Aptâmeros/métodos , Calorimetria/métodos , RNA/químicaRESUMO
The thioredoxin system consists of thioredoxin (Trx), thioredoxin reductase (TrxR) and nicotinamide adenine dinucleotide phosphate (NADPH). Spirulina platensis, which is one of the blue-green algae in the form of spiral rings, belongs to the cyanobacteria class. Spirulina platensis can produce Trx under stress conditions. If it can produce Trx, it also has TrxR activity. Therefore, in this study, the TrxR enzyme was purified for the first time from Spirulina platensis, an algae the most grown and also used as a nutritional supplement in the world. A two-step purification process was used: preparation of the homogenate and 2',5'-ADP sepharose 4B affinity chromatography. The enzyme was purified with a purification fold of 1059.51, a recovery yield of 9.7 %, and a specific activity of 5.77 U/mg protein. The purified TrxR was tested for purity by SDS-PAGE. The molecular weight of its subunit was found to be about 45 kDa. Optimum pH, temperature and ionic strength of the enzyme were pH 7.0, 40 °C and 750 mM in phosphate buffer respectively. The Michaelis constant (Km) and maximum velocity of enzyme (Vmax) values for NADPH and 5,5'-dithiobis (2-nitrobenzoic acid) (DTNB) are 5 µM and 2.2 mM, and 0.0033 U/mL and 0.0044 U/mL, respectively. Storage stability of the purified enzyme was determined at several temperatures. The inhibition effects of Ag+, Cu2+, Al3+ and Se4+ metal ions on the purified TrxR activity were investigated in vitro. While Se4+ ion increased the enzyme activity, other tested metal ions showed different type of inhibitory effects on the Lineweaver-Burk graphs.
Assuntos
Antioxidantes , Spirulina , Tiorredoxina Dissulfeto Redutase , NADP/metabolismo , Tiorredoxina Dissulfeto Redutase/química , Tiorredoxina Dissulfeto Redutase/metabolismo , Cromatografia de Afinidade , Tiorredoxinas/química , Íons , CinéticaRESUMO
Thioredoxin reductase (TrxR, enzyme code [E.C.] 1.6.4.5) is a widely distributed flavoenzyme that catalyzes nicotinamide adenine dinucleotide phosphate (NADPH)-dependent reduction of thioredoxin and many other physiologically important substrates. Spirulina platensis is a blue-green algae that is often used as a dietary supplement. S. platensis is rich in protein, lipid, polysaccharide, pigment, carotenoid, enzyme, vitamins and many other chemicals and exhibits a variety of pharmacological functions. In the present study, a simple and efficient method to purify TrxR from S. platensis tablets is reported. The extractions were carried out using two different methods: heat denaturation and 2',5'-adenosine diphosphate Sepharose 4B affinity chromatography. The enzyme was purified by 415.04-fold over the crude extract, with a 19% yield, and specific activity of 0.7640 U/mg protein. Optimum pH, temperature and ionic strength of the enzyme activity, as well as the Michaelis constant (Km ) and maximum velocity of enzyme (Vmax ) values for NADPH and 5,5'-dithiobis(2-nitrobenzoic acid) were determined. Tested metal ions, vitamins, and drugs showed inhibition effects, except Se4+ ion, cefazolin sodium, teicoplanin, and tobramycin that increased the enzyme activity in vitro. Ag+ , Cu2+ , Mg2+ , Ni2+ , Pb2+ , Zn2+ , Al3+ , Cr3+ , Fe3+ , and V4+ ions; vitamin B3 , vitamin B6 , vitamin C, and vitamin U and aciclovir, azithromycin, benzyladenine, ceftriaxone sodium, clarithromycin, diclofenac, gibberellic acid, glurenorm, indole-3-butyric acid, ketorolac, metformin, mupirocin, mupirocin calcium, paracetamol, and tenofovir had inhibitory effects on TrxR. Ag+ exhibited stronger inhibition than 1-chloro-2,4-dinitrobenzene (a positive control).
Assuntos
Spirulina , Tiorredoxina Dissulfeto Redutase , NADP/metabolismo , Tiorredoxina Dissulfeto Redutase/química , Tiorredoxina Dissulfeto Redutase/metabolismo , Cromatografia de Afinidade , Vitaminas , ÍonsRESUMO
The aim of the study was to purify and characterise recombinant proteins with the potential as an anti-parasite vaccine. Full-length cDNAs encoding seryl-tRNA synthetase (srs-2) were cloned from Haemonchus contortus (HcSRS-2) and Teladorsagia circumcincta (TcSRS-2). TcSRS-2 and HcSRS-2 cDNA (1458bp) encoded proteins of 486 amino acids, each of which was present as a single band of about 55 kDa on SDS-PAGE. Multiple alignments of the protein sequences showed homology of 94% between TcSRS-2 and HcSRS-2, 76-93% with SRS-2s of eight nematodes and 68% with Mus musculus SRS-2. The predicted three-dimensional structures revealed an overall structural homology of TcSRS-2 and HcSRS-2, highly conserved binding and catalytic sites, and minor differences in the tautomerase binding site residues in other nematode SRS-2 homologues. A phylogenetic tree was constructed using helminth and mammalian SRS-2 sequences. Soluble C-terminal SRS-2 proteins were expressed in Escherichia coli strain AY2.4 and purified. Recombinant HcSRS-2 assay shows that the recombinant enzyme was active and stable. The Km and Vmax for ATP were 3.9 ± 1.0 µM and 2.7 ± 0.1 µmol min-1 mg-1 protein, respectively. Antibodies in serum and saliva from field-immune, but not nematode-naïve, sheep recognised recombinant HcSRS-2 and TcSRS-2 in enzyme-linked immunosorbent assays. Recognition of the recombinant proteins by antibodies generated by exposure of sheep to the native enzyme indicates similar antigenicity of the two proteins.
Assuntos
Sequência de Aminoácidos , Anticorpos Anti-Helmínticos , Clonagem Molecular , DNA Complementar , Haemonchus , Filogenia , Proteínas Recombinantes , Alinhamento de Sequência , Doenças dos Ovinos , Trichostrongyloidea , Animais , Haemonchus/enzimologia , Haemonchus/genética , Haemonchus/imunologia , Trichostrongyloidea/enzimologia , Trichostrongyloidea/genética , Trichostrongyloidea/imunologia , Trichostrongyloidea/classificação , Ovinos , Proteínas Recombinantes/imunologia , Proteínas Recombinantes/genética , Proteínas Recombinantes/química , Anticorpos Anti-Helmínticos/sangue , Doenças dos Ovinos/parasitologia , DNA Complementar/química , Tricostrongiloidíase/veterinária , Tricostrongiloidíase/parasitologia , Tricostrongiloidíase/imunologia , Ensaio de Imunoadsorção Enzimática , Eletroforese em Gel de Poliacrilamida , Modelos Moleculares , Hemoncose/veterinária , Hemoncose/parasitologia , Hemoncose/imunologia , Sequência de Bases , Feminino , Camundongos , DNA de Helmintos/químicaRESUMO
The most important area of modern pharmacology is the targeted delivery of drugs, and one of the most promising classes of chemical compounds for creating drugs of this kind are the photochromic spiropyrans, capable of light-controlled biological activity. This work is devoted to the synthesis and study of the photochromic properties of new triphenylphosphonium salts of spiropyrans. It was found that all the synthesized cationic spiropyrans have high photosensitivity, increased resistance to photodegradation and the ability for photoluminescence.
RESUMO
For the first time a pyrrolidinofullerene salt containing a spiropyran group and an ammonium group, capable of reversibly reacting to UV radiation, has been synthesized. Photoinduced reactions of the synthesized compounds were studied using absorption and luminescence spectroscopies, spectral and kinetic characteristics were measured. The hybrid molecule was found to exhibit intrinsic fluorescence even in the spirocyclic form. The C60 derivative showed a higher stability and better spectral and luminescent properties than the precursor.
Assuntos
Antineoplásicos , Fulerenos , Luminescência , Raios Ultravioleta , Cloreto de Sódio , Cloreto de Sódio na DietaRESUMO
Prussian blue analogues are used in electrochemical deionization due to their cation sorption capabilities and ion selectivity properties. Elucidating the fundamental mechanisms underlying intercalation/deintercalation is important for the development of ion-selective electrodes. We examined the thermodynamic and kinetic properties of nickel hexacyanoferrate electrodes by studying different temperatures effects on intercalation/deintercalation with monovalent ions (Li+, Na+, K+, and NH4+) relevant to battery electrode deionization applications. Higher temperatures reduced the interfacial charge transfer resistance and increased the diffusion coefficient of cations in the solid material. Ion transport in the solid material, rather than interfacial charge transfer, was found to be the rate-controlling step, as shown by higher activation energies for ion transport (e.g., 31 ± 3 kJ/mol for K+) than for interfacial charge transfer (5 ± 1 kJ/mol for K+). The largest increase in cation adsorption capacity with temperature was observed for NH4+ (28.1% from 15 to 75 °C) due to its smallest activation energy. These results indicate that ion hydration energy determines the intercalation potential and activation energies of ion transport in solid material control intercalation/deintercalation rate. Together with the endothermic behavior of deintercalation and exothermic behavior of intercalation, the higher operating temperature results in improvement of ion adsorption capacity depending on specific cations.
RESUMO
New salts of photochromic indoline spiropyrans capable of reversibly responding to UV radiation were synthesized to develop light-controlled materials. Photoinduced reactions of the synthesized compounds were studied using absorption and luminescence spectroscopies, and the quantum yields of photoisomerization and other spectral and kinetic characteristics were measured. It was shown that the light sensitivity and photostability of the synthesized compounds are considerably influenced by the length of the spacer between the indole and ammonium nitrogen atoms.
Assuntos
Compostos de Amônio , Benzopiranos , Estrutura Molecular , NitrocompostosRESUMO
Neuraminidase (NA) inhibitors (NAI), oseltamivir and zanamivir, are the main antiviral medications for influenza and monitoring of susceptibility to these antivirals is routinely done by determining 50â% inhibitory concentrations (IC50) with MUNANA substrate. During 2010-2019, levels of A(H3N2) viruses presenting reduced NAI inhibition (RI) were low (~0.75â%) but varied year-on-year. The highest proportions of viruses showing RI were observed during the 2013-2014, 2016-2017 and 2017-2018 Northern Hemisphere seasons. The majority of RI viruses were found to contain positively charged NA amino acid substitutions of N329K, K/S329R, S331R or S334R, being notably higher during the 2016-2017 season. Sialidase activity kinetics were determined for viruses of RI phenotype and contemporary wild-type (WT) viruses showing close genetic relatedness and displaying normal inhibition (NI). RI phenotypes resulted from reduced sialidase activity compared to relevant WT viruses. Those containing S329R or N329K or S331R showed markedly higher Km for the substrate and Ki values for NAIs, while those with S334R showed smaller effects. Substitutions at N329 and S331 disrupt a glycosylation sequon (NDS), confirmed to be utilised by mass spectrometry. However, gain of positive charge at all three positions was the major factor influencing the kinetic effects, not loss of glycosylation. Because of the altered enzyme characteristics NAs carrying these substitutions cannot be assessed reliably for susceptibility to NAIs using standard MUNANA-based assays due to reductions in the affinity of the enzyme for its substrate and the concentration of the substrate usually used.
Assuntos
Vírus da Influenza A Subtipo H3N2/enzimologia , Neuraminidase/metabolismo , Substituição de Aminoácidos , Antivirais/farmacologia , Inibidores Enzimáticos/farmacologia , Genes Virais , Glicosilação , Sequenciamento de Nucleotídeos em Larga Escala , Vírus da Influenza A Subtipo H3N2/efeitos dos fármacos , Vírus da Influenza A Subtipo H3N2/genética , Cinética , Modelos Moleculares , Neuraminidase/antagonistas & inibidores , Neuraminidase/química , Neuraminidase/genética , Oseltamivir/farmacologia , Conformação Proteica , Zanamivir/farmacologiaRESUMO
Lipases are ubiquitous biological macromolecules which have many industrial and environmental applications. The purpose of this study was to purify lipase from Aspergillus fumigatus by using Octyl Sepharose column chromatography. The enzyme was purified by ammonium sulfate precipitation and hydrophobic interaction chromatography which resulted in sevenfold purification. The molecular weight of protein using Native-PAGE was found to be 70 kDa. The apparent molecular weight by SDS-PAGE was found to be 35 kDa which indicated that the enzyme was homodimer. The optimum temperature and pH for activity of the enzyme was found to be 40 °C and 9.0, respectively. The kinetic parameters Vmax and Km of the purified lipase were 10.42 µmol min-1 mg-1 and 9.89 mM, respectively. Detergents Tween-20 and Triton X-100 inhibited enzyme activity. However, there was minimal loss of enzyme activity with SDS and Tween-80. All metal ions inhibited the enzyme activity. Among solvents, maximum loss (65%) in the enzyme activity was in hexane.
Assuntos
Aspergillus fumigatus/enzimologia , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/fisiologia , Cromatografia em Gel , Lipase/isolamento & purificação , Lipase/metabolismo , Sefarose/análogos & derivados , Sulfato de Amônio/química , Aspergillus fumigatus/isolamento & purificação , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/metabolismo , Ativação Enzimática , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Cinética , Metais/farmacologia , Peso Molecular , Sefarose/química , Microbiologia do Solo , Solventes/farmacologia , Especificidade por Substrato , TemperaturaRESUMO
A 1299 bp full length cDNA encoding Teladorsagia circumcincta enolase (TeciENO) was cloned, expressed in Escherichia coli and the recombinant protein purified and its kinetic properties determined. Helminth enolase sequences were used to construct a phylogenetic tree. The predicted protein consisted of 433 amino acids and was present as a single band of about 50 kDa on SDS-PAGE. Multiple alignments of the protein sequence of TeciENO with homologues from other helminths showed 98% similarity with Haemonchus contortus enolase, 78-95% similarity to other nematode sequences and 72-75% similarity to cestode and trematode enolases. Substrate binding sites and conserved regions were identified and were completely conserved in other homologues. The optimum pH for TeciENO activity at 25 °C was pH 7, the Km for 2-phophoglycerate 0.09 ± 0.04 mM and the Vmax was 604 ± 6 nmol min-1 mg-1 protein (both mean ± SD, n = 2). TeciENO activity was inhibited by 11.5% by 1 mM citrate (p < 0.001). Antibodies in both serum and saliva from field-immune, but not nematode-naïve, sheep recognised recombinant TeciENO in enzyme-linked immunosorbent assays. The recognition of the recombinant protein by antibodies generated by exposure of sheep to native enolase indicates similar antigenicity of the two proteins.
Assuntos
Anticorpos Anti-Helmínticos/imunologia , Fosfopiruvato Hidratase/imunologia , Fosfopiruvato Hidratase/metabolismo , Trichostrongyloidea/enzimologia , Trichostrongyloidea/imunologia , Tricostrongiloidíase/veterinária , Abomaso/parasitologia , Sequência de Aminoácidos , Animais , Anticorpos Anti-Helmínticos/sangue , Clonagem Molecular , DNA Complementar , DNA de Helmintos/genética , Ensaio de Imunoadsorção Enzimática , Proteínas de Helminto/química , Proteínas de Helminto/genética , Proteínas de Helminto/imunologia , Proteínas de Helminto/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Fosfopiruvato Hidratase/química , Fosfopiruvato Hidratase/genética , Filogenia , Proteínas Recombinantes , Saliva/imunologia , Ovinos , Doenças dos Ovinos/imunologia , Tricostrongiloidíase/imunologia , Tricostrongiloidíase/parasitologiaRESUMO
A 1023 bp full length cDNA encoding Teladorsagia circumcincta GAPDH (TeciGAPDH) was cloned, expressed in Escherichia coli and the recombinant protein purified and its kinetic properties determined. A phylogenetic tree was constructed using helminth GAPDH sequences. The predicted protein consisted of 341 amino acids and was present as a single band of about 38 kDa on SDS-PAGE. Multiple alignments of the protein sequence of TeciGAPDH with homologues from other helminths showed that the greatest similarity (93%) to the GAPDH of Haemonchus contortus and Dictyocaulus viviparus, 82-86% similarity to the other nematode sequences and 68-71% similarity to cestode and trematode enzymes. Substrate binding sites and conserved regions were identified and were completely conserved in other homologues. At 25 °C, the optimum pH for TeciGAPDH activity was pH 8, the Vmax was 1052 ± 23 nmol min-1 mg-1 protein and the apparent Km for the substrate glyceraldehyde-3-phosphate was 0.02 ± 0.01 mM (both mean ± SD, n = 2). Antibodies in both serum and saliva from field-immune, but not nematode-naïve, sheep recognised recombinant TeciGAPDH in enzyme-linked immunosorbent assays. The recognition of the recombinant protein by antibodies generated by exposure of sheep to native GAPDH indicates similar antigenicity of the two proteins.
Assuntos
Gliceraldeído 3-Fosfato Desidrogenase (NADP+)/imunologia , Trichostrongyloidea/enzimologia , Abomaso/parasitologia , Sequência de Aminoácidos , Animais , Sequência de Bases , DNA Complementar/química , DNA Complementar/isolamento & purificação , DNA de Helmintos/química , DNA de Helmintos/isolamento & purificação , Eletroforese em Gel de Poliacrilamida , Ensaio de Imunoadsorção Enzimática , Gliceraldeído 3-Fosfato Desidrogenase (NADP+)/química , Gliceraldeído 3-Fosfato Desidrogenase (NADP+)/genética , Concentração de Íons de Hidrogênio , Filogenia , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Alinhamento de Sequência , Ovinos , Doenças dos Ovinos/parasitologia , Trichostrongyloidea/classificação , Trichostrongyloidea/genética , Trichostrongyloidea/imunologia , Tricostrongiloidíase/parasitologia , Tricostrongiloidíase/veterináriaRESUMO
BACKGROUND: Manganese peroxidase (MnP) from Irpex lacteus F17 has been shown to have a strong ability to degrade recalcitrant aromatic pollutants. In this study, a recombinant MnP from I. lacteus F17 was expressed in Escherichia coli Rosetta (DE3) in the form of inclusion bodies, which were refolded to achieve an active enzyme. Further, we optimized the in vitro refolding conditions to increase the recovery yield of the recombinant protein production. Additionally, we attempted to express recombinant MnP in soluble form in E. coli, and compared its activity with that of refolded MnP. RESULTS: Refolded MnP was obtained by optimizing the in vitro refolding conditions, and soluble MnP was produced in the presence of four additives, TritonX-100, Tween-80, ethanol, and glycerol, through incubation at 16 °C. Hemin and Ca2+ supplementation was crucial for the activity of the recombinant protein. Compared with refolded MnP, soluble MnP showed low catalytic efficiencies for Mn2+ and H2O2 substrates, but the two enzymes had an identical, broad range substrate specificity, and the ability to decolorize azo dyes. Furthermore, their enzymatic spectral characteristics were analysed by circular dichroism (CD), electronic absorption spectrum (UV-VIS), fluorescence and Raman spectra, indicating the differences in protein conformation between soluble and refolded MnP. Subsequently, size exclusion chromatography (SEC) and dynamic light scattering (DLS) analyses demonstrated that refolded MnP was a good monomer in solution, while soluble MnP predominantly existed in the oligomeric status. CONCLUSIONS: Our results showed that two forms of recombinant MnP could be expressed in E. coli by varying the culture conditions during protein expression.
Assuntos
Basidiomycota/enzimologia , Basidiomycota/genética , Escherichia coli/enzimologia , Escherichia coli/genética , Peroxidases/química , Peroxidases/metabolismo , Ativação Enzimática , Estabilidade Enzimática , Peroxidases/genética , Conformação Proteica , Redobramento de Proteína , SolubilidadeRESUMO
Mycobacterium tuberculosis dTDP-d-glucose 4,6-dehydratase (RmlB) is the second enzyme for the biosynthesis of dTDP-l-rhamnose, which is a sugar donor to the synthesis of the cell wall linker, d-N-acetylglucosamine-l-rhamnose. RmlB is essential to mycobacterial growth and is not found in humans; therefore, it is a potential target for developing new anti-tuberculosis drugs. So far, there has been no suitable method for high-throughput screening of RmlB inhibitors. Here, the recombinant M. tuberculosis RmlB was purified and an absorbance-based microtiter plate assay was developed for RmlB activity. It could be used for high-throughput screening of RmlB inhibitors. The kinetic properties of M. tuberculosis RmlB, including optimal pH, optimal temperature, the effect of metal ions, and the kinetic parameters, were determined with this assay. The inhibitory effects of dTTP and dTDP on M. tuberculosis RmlB were also studied with the assay.
Assuntos
Antituberculosos/farmacologia , Inibidores Enzimáticos/farmacologia , Ensaios de Triagem em Larga Escala , Hidroliases/antagonistas & inibidores , Mycobacterium tuberculosis/enzimologia , Antituberculosos/química , Bioensaio , Inibidores Enzimáticos/química , Glucose/análogos & derivados , Glucose/química , Glucose/farmacologia , Hidroliases/metabolismo , Cinética , Testes de Sensibilidade Microbiana , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/isolamento & purificação , Nucleotídeos de Timina/química , Nucleotídeos de Timina/farmacologiaRESUMO
Full length cDNAs encoding phosphofructokinase (PFK) were cloned from Teladorsagia circumcincta (TcPFK) and Haemonchus contortus (HcPFK). TcPFK (2361 bp) and HcPFK (2367 bp) cDNA encoded 787 and 789 amino acid proteins respectively. The predicted amino acid sequences showed 98% similarity with each other and 70% with a Caenorhabditis elegans PFK. Substrate binding sites were completely conserved in both proteins. Soluble N-terminal His-tagged PFK proteins were expressed in Escherichia coli strain BL21, purified and characterised. The recombinant TcPFK and HcPFK had very similar kinetic properties: the pH optima were pH 7.0, Km for fructose 6-phosphate was 0.50 ± 0.01 and 0.55 ± 0.01 mM respectively when higher (inhibiting concentration, 0.3 mM) ATP concentration was used and the curve was sigmoidal. The Vmax for TcPFK and HcPFK were 1110 ± 16 and 910 ± 10 nM min(-1 )mg(-1) protein respectively. Lower ATP concentration (non-inhibiting, 0.01 mM) did not change the Vmax for TcPFK and HcPFK (890 ± 10 and 860 ± 12 nM min(-1 )mg(-1) protein) but the substrate affinity doubled and Km for fructose 6-phosphate were 0.20 ± 0.05 and 0.25 ± 0.01 mM respectively. Recognition of TcPFK and HcPFK by mucosal and serum antibodies in nematode exposed animals demonstrates antigenicity and suggests involvement in the host response to nematode infection.
Assuntos
Abomaso/parasitologia , Fosfofrutoquinases/química , Doenças dos Ovinos/parasitologia , Trichostrongyloidea/enzimologia , Tricostrongiloidíase/veterinária , Sequência de Aminoácidos , Animais , Anticorpos Anti-Helmínticos/análise , Anticorpos Anti-Helmínticos/sangue , Anticorpos Anti-Helmínticos/imunologia , Sequência de Bases , Clonagem Molecular , DNA Complementar/química , DNA de Helmintos/química , Hemoncose/imunologia , Hemoncose/parasitologia , Hemoncose/veterinária , Haemonchus/classificação , Haemonchus/enzimologia , Haemonchus/genética , Haemonchus/imunologia , Cinética , Dados de Sequência Molecular , Fosfofrutoquinases/classificação , Fosfofrutoquinases/genética , Fosfofrutoquinases/imunologia , Filogenia , Proteínas Recombinantes/química , Proteínas Recombinantes/classificação , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Saliva/imunologia , Alinhamento de Sequência , Ovinos , Doenças dos Ovinos/imunologia , Trichostrongyloidea/classificação , Trichostrongyloidea/genética , Trichostrongyloidea/imunologia , Tricostrongiloidíase/imunologia , Tricostrongiloidíase/parasitologiaRESUMO
Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzymopathy in the world. More than 160 mutations causing the disease have been identified, but only 10% of these variants have been studied at biochemical and biophysical levels. In this study we report on the functional and structural characterization of three naturally occurring variants corresponding to different classes of disease severity: Class I G6PD Durham, Class II G6PD Santa Maria, and Class III G6PD A+. The results showed that the G6PD Durham (severe deficiency), and the G6PD Santa Maria and A+ (less severe deficiency) (Class I, II and III, respectively) affect the catalytic efficiency of these enzymes, are more sensitive to temperature denaturing, and affect the stability of the overall protein when compared to the wild type WT-G6PD. In the variants, the exposure of more and buried hydrophobic pockets was induced and monitored with 8-Anilinonaphthalene-1-sulfonic acid (ANS) fluorescence, directly affecting the compaction of structure at different levels and probably reducing the stability of the protein. The degree of functional and structural perturbation by each variant correlates with the clinical severity reported in different patients.
Assuntos
Variação Genética , Glucosefosfato Desidrogenase/química , Glucosefosfato Desidrogenase/genética , Modelos Moleculares , Conformação Molecular , Mutação , Catálise , Ativação Enzimática , Expressão Gênica , Glucosefosfato Desidrogenase/metabolismo , Humanos , Cinética , Estabilidade Proteica , Proteínas Recombinantes , Relação Estrutura-Atividade , TermodinâmicaRESUMO
Listeria monocytogenes is adaptable to low pH environments and therefore crosses the intestinal barrier to establish systemic infections. L. monocytogenes aguA1 and aguA2 encode putative agmatine deiminases (AgDIs) AguA1 and AguA2. Transcription of aguA1 and aguA2 was significantly induced at pH 5.0. Deletion of aguA1 significantly impaired its survival both in gastric fluid at pH 2.5 and in mouse stomach, whereas aguA2 deletion did not show significant defect of survival in gastric fluid. With agmatine as the sole substrate, AguA1 expressed in Escherichia coli was optimal at 25 °C and over a wide range of pH from 3.5 to 10.5. Recombinant AguA2 showed no deiminase activity. Site-directed mutagenesis revealed that all nine AguA1 mutants completely lost enzymatic activity. AguA2 acquired AgDI activity only when Cys-157 was mutated to glycine. AguA1 mutation at the same site, G157C, also inactivated the enzyme. Thus, we have discovered Gly-157 as a novel residue other than the known catalytic triad (Cys-His-Glu/Asp) in L. monocytogenes that is critical for enzyme activity. Of the two putative AgDIs, we conclude that only AguA1 functionally participates in the AgDI pathway and mediates acid tolerance in L. monocytogenes.
Assuntos
Proteínas de Bactérias/metabolismo , Hidrolases/metabolismo , Listeria monocytogenes/enzimologia , Sequência de Aminoácidos , Animais , Proteínas de Bactérias/genética , Ligação Competitiva , Catálise , Biologia Computacional , Feminino , Teste de Complementação Genética , Glicina/química , Concentração de Íons de Hidrogênio , Hidrolases/genética , Concentração Inibidora 50 , Camundongos , Camundongos Endogâmicos ICR , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Homologia de Sequência de Aminoácidos , Estômago/microbiologia , Especificidade por SubstratoRESUMO
BACKGROUND: α-Amylase is an important digestive enzyme required for the optimal growth and development of insects. Several insect α-amylases had been purified and their physical and chemical properties were characterized. Insect α-amylases of different orders display variability in structure, properties and substrate specificity. Such diverse properties of amylases could be due to different feeding habits and gut environment of insects. KEY POINTS: In this review, structural features and properties of several insect α-amylases were compared. This could be helpful in exploring the diversity in characteristics of α-amylase between the members of the same class (insecta). Properties like pH optima are reflected in enzyme structural features. In plants, α-amylase inhibitors (α-AIs) occur as part of natural defense mechanisms against pests by interfering in their digestion process and thus could also provide access to new pest management strategies. AIs are quite specific in their action; therefore, these could be employed according to their effectiveness against target amylases. Potential of transgenics with α-AIs has also been discussed for insect resistance and controlling infestation. CONCLUSIONS: The differences in structural features of insect α-amylases provided reasons for their efficient functioning at different pH and the specificity towards various substrates. Various proteinaceous and non-proteinaceous inhibitors discussed could be helpful in controlling pest infestation. In depth detailed studies are required on proteinaceous α-AI-α-amylase interaction at different pH's as well as the insect proteinase action on these inhibitors before selecting the α-AI for making transgenics resistant to particular insect.
Assuntos
Proteínas de Insetos , Isoenzimas , alfa-Amilases , Animais , Inibidores Enzimáticos/farmacologia , Proteínas de Insetos/antagonistas & inibidores , Proteínas de Insetos/química , Proteínas de Insetos/metabolismo , Insetos , Isoenzimas/antagonistas & inibidores , Isoenzimas/química , Isoenzimas/metabolismo , Plantas Geneticamente Modificadas , Especificidade por Substrato , alfa-Amilases/antagonistas & inibidores , alfa-Amilases/química , alfa-Amilases/metabolismoRESUMO
Amino acid depletion therapy is a promising approach for cancer treatment. It exploits the differences in the metabolic processes between healthy and cancerous cells. Certain microbial enzymes induce cancer cell apoptosis by removing essential amino acids. L-asparaginase is an enzyme approved by the FDA for the treatment of acute lymphoblastic leukemia. The enzymes currently employed in clinics come from two different sources: Escherichia coli and Erwinia chrysanthemi. Nevertheless, the search for improved enzymes and other sources continues because of several factors, including immunogenicity, in vivo instability, and protease degradation. Before determining whether L-asparaginase is clinically useful, research should consider the Michaelis constant, turnover number, and maximal velocity. The identification of L-asparaginase from microbial sources has been the subject of various studies. The primary goals of this review are to explore the most current approaches used in the search for therapeutically useful L-asparaginases and to establish whether these investigations identified the crucial characteristics of L-asparaginases before declaring their therapeutic potential.
RESUMO
Vitamins, as indispensable organic compounds in life activities, demonstrate a complex and refined metabolic network in organisms. This network involves the coordination of multiple enzymes and the integration of various metabolic pathways. Despite the achievements in metabolic engineering and catalytic mechanism research, the lack of studies regarding detailed enzymatic properties for a large number of key enzymes limits the enhancement of vitamin production efficiency and hinders the in-depth understanding and optimization of vitamin synthesis mechanisms. Such limitations not only restrict the industrial application of vitamins but also impede the development of related bio-technologies. This study comprehensively reviews the research progress in the enzymes involved in vitamin biosynthesis and details the current status of research on the enzymes of 13 vitamin synthesis pathways, including their catalytic mechanisms, kinetic properties, and applications in biology. In addition, this study compares the properties of enzymes involved in vitamin metabolic pathways and the glycolysis pathway, and reveals the characteristics of catalytic efficiency and substrate affinity of enzymes in vitamin synthesis pathways. Furthermore, this study discusses the potential and prospects of applying deep learning methods to the research on properties of enzymes associated with vitamin biosynthesis, giving new insights into the production and optimization of vitamins.