Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 4.657
Filtrar
1.
Inorg Chem ; 58(15): 9557-9561, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31313577

RESUMO

An iron(III) methoxide complex reacts with para-substituted triarylmethyl radicals to give iron(II) and methoxyether products. Second-order rate constants for the radical derivatives were obtained. Hammett and Marcus plots suggest the radical transfer reactions proceed via a concerted process. Calculations support the concerted nature of these reactions involving a single transition state with no initial charge transfer. These findings have implications for the radical "rebound" step invoked in nonheme iron oxygenases, halogenases, and related synthetic catalysts.


Assuntos
Compostos Férricos/metabolismo , Compostos Ferrosos/metabolismo , Oxirredutases/metabolismo , Oxigênio/metabolismo , Oxigenases/metabolismo , Biocatálise , Compostos Férricos/química , Compostos Ferrosos/química , Estrutura Molecular , Oxirredutases/química , Oxigênio/química , Oxigenases/química
2.
Chem Commun (Camb) ; 55(62): 9148-9151, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31304493

RESUMO

Using superoxide reductase as a model system, a computational approach reveals how histidine tautomerism tunes the redox properties of metalloenzymes to enable their catalytic function. Inspired by these experimentally inaccessible insights, non-canonical histidine congeners are introduced as new versatile tools for the rational engineering of biological transition metal sites.


Assuntos
Oxirredutases/química , Oxirredutases/metabolismo , Elementos de Transição/metabolismo , Biocatálise , Modelos Moleculares , Estrutura Molecular , Oxirredução , Elementos de Transição/química
3.
Chem Commun (Camb) ; 55(54): 7836-7839, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31215559

RESUMO

It is of great importance to determine the superoxide anion (O2˙-), a kind of active free radical that plays important roles in catalytic and biological processes. We present here a high-energy-state biomimetic enzyme with extraordinary activity for O2˙- by inducing surface oxygen defects in MnTiO3 nanodiscs. Oxygen defects enable surface rich active Mn sites with high oxidation ability, which significantly promote the adsorption and electro-oxidation of O2˙-. The oxygen deficient MnTiO3 towards O2˙- exhibits a sensitivity of 126.48 µA µM-1 cm-2 and a detection limit of 1.54 nM, among the best performance of O2˙- sensing platforms.


Assuntos
Materiais Biomiméticos/química , Compostos de Manganês/química , Nanoestruturas/química , Óxidos/química , Superóxidos/análise , Titânio/química , Técnicas Eletroquímicas/métodos , Limite de Detecção , Oxirredução , Oxirredutases/química
4.
Nat Commun ; 10(1): 2074, 2019 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-31061390

RESUMO

Hydride transfers play a crucial role in a multitude of biological redox reactions and are mediated by flavin, deazaflavin or nicotinamide adenine dinucleotide cofactors at standard redox potentials ranging from 0 to -340 mV. 2-Naphthoyl-CoA reductase, a key enzyme of oxygen-independent bacterial naphthalene degradation, uses a low-potential one-electron donor for the two-electron dearomatization of its substrate below the redox limit of known biological hydride transfer processes at E°' = -493 mV. Here we demonstrate by X-ray structural analyses, QM/MM computational studies, and multiple spectroscopy/activity based titrations that highly cooperative electron transfer (n = 3) from a low-potential one-electron (FAD) to a two-electron (FMN) transferring flavin cofactor is the key to overcome the resonance stabilized aromatic system by hydride transfer in a highly hydrophobic pocket. The results evidence how the protein environment inversely functionalizes two flavins to switch from low-potential one-electron to hydride transfer at the thermodynamic limit of flavin redox chemistry.


Assuntos
Proteínas de Bactérias/química , Coenzimas/química , Flavinas/química , Modelos Moleculares , Oxirredutases/química , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Coenzimas/metabolismo , Simulação por Computador , Cristalografia por Raios X , Transporte de Elétrons , Flavinas/metabolismo , Naftalenos/química , Naftalenos/metabolismo , Oxirredutases/isolamento & purificação , Oxirredutases/metabolismo , Estrutura Terciária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Análise Espectral
5.
Acta Crystallogr D Struct Biol ; 75(Pt 3): 333-341, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30950404

RESUMO

The hydroxylamine oxidoreductase/hydrazine dehydrogenase (HAO/HDH) protein family constitutes an important group of octaheme cytochromes c (OCCs). The majority of these proteins form homotrimers, with their subunits being covalently attached to each other via a rare cross-link between the catalytic heme moiety and a conserved tyrosine residue in an adjacent subunit. This covalent cross-link has been proposed to modulate the active-site heme towards oxidative catalysis by distorting the heme plane. In this study, the crystal structure of a stable complex of an HAO homologue (KsHAOr) with its diheme cytochrome c redox partner (KsDH) from the anammox bacterium Kuenenia stuttgartiensis was determined. KsHAOr lacks the tyrosine cross-link and is therefore tuned to reductive catalysis. The molecular model of the KsHAOr-KsDH complex at 2.6 Šresolution shows a heterododecameric (α6ß6) assembly, which was also shown to be the oligomeric state in solution by analytical ultracentrifugation and multi-angle static light scattering. The 60-heme-containing protein complex reveals a unique extended electron transfer pathway and provides deeper insights into catalysis and electron transfer in reductive OCCs.


Assuntos
Proteínas de Bactérias/química , Transporte de Elétrons , Bactérias Anaeróbias Gram-Negativas/enzimologia , Oxirredutases/química , Bactérias/metabolismo , Modelos Moleculares
6.
Inorg Chem ; 58(9): 5787-5798, 2019 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-31016970

RESUMO

The reaction of the Mannich base ligand (H2L = N, N'-dimethyl- N, N'-bis(2-hydroxy-3-methoxy-5-methylbenzyl)ethylenediamine) with Co(OAc)2·4H2O and Ln(III) nitrate salts (Ln = Gd, Tb, and Dy) under basic conditions afforded three carbonato-bridged isostructural tetranuclear heterometallic Co(II)-Ln(III) complexes (Co2Gd2L2(µ4-CO3)2(NO3)2] (1), [Co2Tb2L2(µ4-CO3)2(NO3)2] (2), and [Co2Dy2L2(µ4-CO3)2(NO3)2] (3)) by atmospheric CO2 fixation. In all structures, two dinuclear [(CoIIL)LnIII(NO3)] units are linked via two µ4-carbonato groups to form the tetranuclear CoII2LnIII2 core. The geometry around two penta-coordinated Co(II) ions is distorted square pyramid, and that around two nona-coordinated Ln(III) ions is intermediate between "spherical tricapped trigonal prism" and "spherical capped square antiprism" in all complexes. The complexes (1-3) showed catecholase-like and phenoxazinone-synthase-like catalytic activities. The kcat values calculated for the catecholase-like reaction were 254.5, 272.4, and 291.3 h-1, and for the phenoxazinone-synthase-like reaction they were 2930.6, 2965.2, and 2998.5 h-1 for complexes 1-3, respectively. The probable pathways for these two oxidase reactions have been proposed by the analyses of mass spectral data. For all of the compounds, the variable temperature magnetic susceptibility and isothermal magnetization data were investigated. The complexes exhibited overall ferromagnetic behavior, which was evident from the isothermal magnetization curves. AC magnetic susceptibility measurements revealed the slow relaxation of magnetization in complexes 2 and 3 but very negligible in 1. The activation energy barriers ( Ueff) for the slow relaxation process were evaluated and found to be 1.99, 2.79, and 8.98 K for 1, 2, and 3, respectively.


Assuntos
Materiais Biomiméticos/química , Dióxido de Carbono/química , Cobalto/química , Complexos de Coordenação/química , Elementos da Série dos Lantanídeos/química , Bases de Mannich/química , Oxirredutases/química , Catálise , Ligantes , Imãs/química , Modelos Moleculares
7.
J Nanobiotechnology ; 17(1): 54, 2019 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-30992018

RESUMO

BACKGROUND: Nanomaterials that exhibit intrinsic enzyme-like characteristics have shown great promise as potential antibacterial agents. However, many of them exhibit inefficient antibacterial activity and biosafety problems that limit their usefulness. The development of new nanomaterials with good biocompatibility and rapid bactericidal effects is therefore highly desirable. Here, we show a new type of terbium oxide nanoparticles (Tb4O7 NPs) with intrinsic oxidase-like activity for in vitro and in vivo antibacterial application. RESULTS: We find that Tb4O7 NPs can quickly oxidize a series of organic substrates in the absence of hydrogen peroxide. The oxidase-like capacity of Tb4O7 NPs allows these NPs to consume antioxidant biomolecules and generate reactive oxygen species to disable bacteria in vitro. Moreover, the in vivo experiments showed that Tb4O7 NPs are efficacious in wound-healing and are protective of normal tissues. CONCLUSIONS: Our results reveal that Tb4O7 NPs have intrinsic oxidase-like activity and show effective antibacterial ability both in vitro and in vivo. These findings demonstrate that Tb4O7 NPs are effective antibacterial agents and may have a potential application in wound healing.


Assuntos
Antibacterianos/química , Escherichia coli , Nanopartículas Metálicas/química , Óxidos/química , Oxirredutases/química , Staphylococcus aureus , Térbio/química , Cicatrização , Animais , Antibacterianos/farmacologia , Materiais Biocompatíveis/química , Sobrevivência Celular , Escherichia coli/efeitos dos fármacos , Hemólise , Células Endoteliais da Veia Umbilical Humana , Humanos , Camundongos Endogâmicos BALB C , Óxidos/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Staphylococcus aureus/efeitos dos fármacos , Térbio/farmacologia
8.
Phytochemistry ; 162: 1-9, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30844490

RESUMO

Pinoresinol/lariciresinol reductase (PLR), an NADPH-dependent reductase that catalyzes the sequential reduction of pinoresinol into secoisolariciresinol via Lariciresinol, can lead to the structural and stereochemical diversity of lignans. The relationship between substrate-selective reaction of PLR and sequence homology still remains unclear. In this study, we focused on the contribution of the variable region between PLRs in determining substrate selectivity. Here, two CsPLRs (CsPLR1 and CsPLR2) were identified in the tea plant (Camellia sinensis var. sinensis cv. Shuchazao). In vitro enzymatic assays showed that CsPLR1 could convert (+)- and (-)-pinoresinol into lariciresinol or secoisolariciresinol, whereas CsPLR2 catalyzed (+)-pinoresinol enantioselectively into (-)-secoisolariciresinol. Homology modeling and site-directed mutagenesis were used to examine the role of a variable loop in catalysis and substrate selectivity. The L174I mutant in CsPLR1 lost the capacity to reduce either (+)- or (-)-pinoresinol but retained the ability to catalyze the reduction of (-)-lariciresinol. These findings provide a basis for better understanding of the substrate-selective reaction of PLR.


Assuntos
Camellia sinensis/enzimologia , Oxirredutases/química , Oxirredutases/metabolismo , Butileno Glicóis/metabolismo , Furanos/metabolismo , Lignanas/metabolismo , Mutagênese Sítio-Dirigida , Oxirredutases/genética , Homologia de Sequência de Aminoácidos , Especificidade por Substrato
9.
Nano Lett ; 19(4): 2478-2488, 2019 04 10.
Artigo em Inglês | MEDLINE | ID: mdl-30884235

RESUMO

Although biosensors based on nanowires-field effect transistor were proved extraordinarily efficient in fundamental applications, screening of charges due to the high-ionic strength of most physiological solutions imposes severe limitations in the design of smart, "real-time" sensors, as the biosample solution has to be previously desalted. This work describes the development of a novel nanowire biosensor that performs extracellular real-time multiplex sensing of small molecular metabolites, the true indicators of the body's chemistry machinery, without any preprocessing of the biosample. Unlike other nanoFET devices that follow direct binding of analytes to their surfaces, our nanodevice acts by sensing the oxidation state of redox-reactive chemical species bound to its surface. The device's surface array is chemically modified with a reversible redox molecular system that is sensitive to H2O2 down to 100 nM, coupled with a suite of corresponding oxidase enzymes that convert target metabolites to H2O2, enabling the direct prompt analysis of complex biosamples. This modality was successfully demonstrated for the real-time monitoring of cancer cell samples' metabolic activity and evaluating chemotherapeutic treatment options for cancer. This distinctive system displays ultrasensitive, selective, noninvasive, multiplex, real-time, label-free, and low-cost sensing of small molecular metabolites in ultrasmall volumes of complex biosamples, in the single-microliter scale, placing our technology at the forefront of this cutting-edge field.


Assuntos
Técnicas Biossensoriais/métodos , Metabolômica/métodos , Neoplasias/metabolismo , Oxirredução , Linhagem Celular Tumoral , Humanos , Peróxido de Hidrogênio/metabolismo , Dispositivos Lab-On-A-Chip , Nanofios/química , Neoplasias/diagnóstico , Neoplasias/patologia , Oxirredutases/química , Propriedades de Superfície , Transistores Eletrônicos
10.
Biochim Biophys Acta Bioenerg ; 1860(5): 375-382, 2019 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-30910528

RESUMO

The alternative oxidase (AOX) is a monotopic diiron carboxylate protein which catalyzes the four-electron reduction of dioxygen to water by ubiquinol. Although we have recently determined the crystal structure of Trypanosoma brucei AOX (TAO) in the presence and absence of ascofuranone (AF) derivatives (which are potent mixed type inhibitors) the mechanism by which ubiquinol and dioxygen binds to TAO remain inconclusive. In this article, ferulenol was identified as the first competitive inhibitor of AOX which has been used to probe the binding of ubiquinol. Surface plasmon resonance reveals that AF is a quasi-irreversible inhibitor of TAO whilst ferulenol binding is completely reversible. The structure of the TAO-ferulenol complex, determined at 2.7 Å, provided insights into ubiquinol binding and has also identified a potential dioxygen molecule bound in a side-on conformation to the diiron center for the first time.


Assuntos
Proteínas Mitocondriais/química , Oxirredutases/química , Oxigênio/química , Proteínas de Plantas/química , Proteínas de Protozoários/química , Trypanosoma brucei brucei/enzimologia , Ubiquinona/análogos & derivados , Cumarínicos/química , Proteínas Mitocondriais/metabolismo , Oxirredutases/metabolismo , Oxigênio/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Protozoários/metabolismo , Ressonância de Plasmônio de Superfície , Ubiquinona/química , Ubiquinona/metabolismo
11.
Org Lett ; 21(7): 2330-2334, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30900461

RESUMO

Ascochlorin is a medicinally important fungal meroterpenoid. Its biosynthetic pathway in Fusarium sp. was identified, and the stereoselective epoxidation of the farnesyl group by the multidomain, soluble P450 monooxygenase AscE and the subsequent formation of the unique timethylcyclohexanone ring by the membrane-bound cyclase AscF were investigated. Precursor-directed biosynthesis generated novel bromo-substituted derivatives, which exhibited potent cytotoxic activities. This study paves the way for the future metabolic engineering of medicinally important meroterpenoids for drug discovery.


Assuntos
Alcenos/química , Fungos/metabolismo , Fusarium/química , Oxigenases de Função Mista/metabolismo , Oxirredutases/metabolismo , Fenóis/química , Terpenos/química , Vias Biossintéticas , Oxigenases de Função Mista/química , Estrutura Molecular , Oxirredutases/química , Oxirredutases/isolamento & purificação , Terpenos/isolamento & purificação
12.
J Phys Chem Lett ; 10(7): 1450-1456, 2019 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-30855973

RESUMO

Redox proteins and enzymes are at risk of irreversible oxidative damage from highly oxidizing intermediates generated in the active site in the case of unsuccessful functional reaction. Chains of tyrosine and/or tryptophan residues have been recently proposed to provide protection to the active site and the whole protein by delivering oxidizing equivalents (holes) out of the protein via a multistep hopping mechanism. In the present work we use a hybrid quantum/classical theoretical-computational methodology based on the perturbed matrix method and on molecular dynamics simulations to calculate the oxidation potential difference along a chain of tyrosine and tryptophan residues in a human redox enzyme of major importance, a superoxide dismutase, which acts as antioxidant defense. We show that the hole hopping is thermodynamically favored along such a chain and that the hopping propensity is strongly affected by the protein environment and in particular by the active site and its second coordination sphere.


Assuntos
Oxirredutases/metabolismo , Domínio Catalítico , Simulação de Dinâmica Molecular , Oxirredução , Oxirredutases/química , Teoria Quântica , Eletricidade Estática , Superóxido Dismutase/química , Superóxido Dismutase/metabolismo , Termodinâmica , Triptofano/química , Tirosina/química
13.
Z Naturforsch C ; 74(3-4): 91-100, 2019 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-30789828

RESUMO

Accelerated generation of bio-based materials is vital to replace current synthetic polymers obtained from petroleum with more sustainable options. However, many building blocks available from renewable resources mainly contain unreactive carbon-carbon bonds, which obstructs their efficient polymerization. Herein, we highlight the potential of applying biocatalysis to afford tailored functionalization of the inert carbocyclic core of multicyclic terpenes toward advanced materials. As a showcase, we unlock the inherent monomer reactivity of norcamphor, a bicyclic ketone used as a monoterpene model system in this study, to afford polyesters with unprecedented backbones. The efficiencies of the chemical and enzymatic Baeyer-Villiger transformation in generating key lactone intermediates are compared. The concepts discussed herein are widely applicable for the valorization of terpenes and other cyclic building blocks using chemoenzymatic strategies.


Assuntos
Lactonas/química , Norbornanos/química , Oxirredutases/química , Poliésteres/síntese química , Terpenos/química , Biocatálise , Ciclização , Humanos , Lactonas/metabolismo , Norbornanos/metabolismo , Oxirredução , Oxirredutases/metabolismo , Poliésteres/metabolismo , Polimerização , Prenilação , Terpenos/metabolismo
14.
Org Lett ; 21(5): 1475-1479, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30762374

RESUMO

Fumiquinazolines are multicyclic peptidyl alkaloids where FAD-dependent oxidases are main tailing redox enzymes in their biosynthesis. Here, we characterized the use of an α-KG/Fe(II)-dependent dioxygenase (α-KGD) as a new strategy in Nature to increase structural complexity in fumiquinazolines biosynthesis by elucidating the concise three enzymes biosynthetic pathway of heptacyclical alanditrypinone (1). Further genome mining led to the discovery of additional gene cluster with α-KGD and trimodular NRPS as partner, which generates diverse fumiquinazolines.


Assuntos
Alcaloides/química , Oxirredutases/metabolismo , Peptídeos/metabolismo , Quinazolinas/metabolismo , Vias Biossintéticas , Estrutura Molecular , Família Multigênica , Oxirredução , Oxirredutases/química , Peptídeos/química , Quinazolinas/química
15.
J Biochem ; 166(1): 67-75, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30715389

RESUMO

Aspergillus oryzae RIB40 formate oxidase has Arg87 and Arg554 near the formyl group and O(4) atom of 8-formyl-flavin adenine dinucleotide (FAD), respectively, with Asp396 neighbouring Arg554. Herein, we probed the roles of these three residues in modification of FAD to 8-formyl-FAD. Replacement of Arg87 or Arg554 with Lys or Ala decreased and abolished the modification, respectively. Replacement of Asp396 with Ala or Asn lowered the modification rate. The observation of unusual effects of maintaining pH 7.0 on the modification in R87K, R554K and D396 variants indicates initial and subsequent processes with different pH dependencies. Comparison of the initial process at pH 4.5 and 7.0 suggests that the microenvironment around Arg87 and the protonation state of Asp396 affect the initial process in the native enzyme. Comparison of the crystal structures of native and R554 variants showed that the replacements had minimal effect on catalytic site structure. The positively charged Arg87 might contribute to the formation of an anionic quinone-methide tautomer intermediate, while the positively charged Arg554, in collaboration with the negatively charged Asp396, might stabilize this intermediate and form a hydrogen bonding network with the N(5)/O(4) region, thereby facilitating efficient FAD modification.


Assuntos
Aspergillus oryzae/enzimologia , Oxirredutases/metabolismo , Mononucleotídeo de Flavina/química , Mononucleotídeo de Flavina/metabolismo , Modelos Moleculares , Oxirredutases/química
16.
J Ind Microbiol Biotechnol ; 46(5): 635-647, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30790119

RESUMO

Cholesterol oxidase, steroid C27 monooxygenase and 3-ketosteroid-Δ1-dehydrogenase are key enzymes involved in microbial catabolism of sterols. Here, three isoenzymes of steroid C27 monooxygenase were firstly characterized from Mycobacterium neoaurum as the key enzyme in sterol C27-hydroxylation. Among these three isoenzymes, steroid C27 monooxygenase 2 exhibits the strongest function in sterol catabolism. To improve androst-1,4-diene-3,17-dione production, cholesterol oxidase, steroid C27 monooxygenase 2 and 3-ketosteroid-Δ1-dehydrogenase were coexpressed to strengthen the metabolic flux to androst-1,4-diene-3,17-dione, and 3-ketosteroid 9α-hydroxylase, which catalyzes the androst-1,4-diene-3,17-dione catabolism, was disrupted to block the androst-1,4-diene-3,17-dione degradation pathway in M. neoaurum JC-12. Finally, the recombinant strain JC-12S2-choM-ksdd/ΔkshA produced 20.1 g/L androst-1,4-diene-3,17-dione, which is the highest reported production with sterols as substrate. Therefore, this work is hopes to pave the way for efficient androst-1,4-diene-3,17-dione production through metabolic engineering.


Assuntos
Androstadienos/química , Isoenzimas/metabolismo , Micobactérias não Tuberculosas/metabolismo , Fitosteróis/metabolismo , Esteróis/química , Hidrocarboneto de Aril Hidroxilases/química , Microbiologia Industrial , Engenharia Metabólica , Metabolismo , Oxigenases de Função Mista/metabolismo , Oxirredutases/química , Plasmídeos/metabolismo , Polienos/metabolismo , Esteroide Hidroxilases/química
17.
Eur J Med Genet ; 62(7): 103631, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30790670

RESUMO

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is one of the most common causes of sudden cardiac death (SCD) during childhood and in adolescence. Trans-2, 3-enoyl-CoA reductase-like (Tecrl) gene mutations (Arg196Gln and c.331+1G > A splice site mutation) were first reported in CPVT. Tecrl homozygous c.331+1G > A splice site mutation in iPSCs revealed a definite correlation between Tecrl and Ca2+ transport in cardiomyocytes. However, no other researchers have confirmed Tecrl mutations in CPVT with literature review. In this study, a case of compound heterozygosity in the Tecrl gene (Arg196Gln and c.918+3T > G splice site mutation) was first identified in a 13-year-old boy with CPVT by whole-exome sequencing (WES) and confirmed by Sanger sequence. Support vector machine and neural network analysis predicted that Arg196Gln mutation could decrease the stability of Tecrl structure, the confidence scores were -0.8929 and -0.9930. A STRUM server also confirmed that Arg196Gln mutation may decrease the binding capacity of the substrate and cause an amino acid substitution immediately upstream of the 3-oxo-5-alpha steroid 4-dehydrogenase domain. According to the "human splicing finder" indication and Alamut Visual Splicing Prediction, the c.918 + 3T > G mutation could influence Tecrl variable splicing. Thus, we confirmed that Tecrl as a new gene which is associated with CPVT.


Assuntos
Oxirredutases/genética , Taquicardia Ventricular/genética , Adolescente , Sítios de Ligação , Cálcio/metabolismo , Heterozigoto , Humanos , Masculino , Mutação , Miócitos Cardíacos/metabolismo , Oxirredutases/química , Oxirredutases/metabolismo , Linhagem , Ligação Proteica , Estabilidade Proteica , Sítios de Splice de RNA , Taquicardia Ventricular/patologia
18.
Biosens Bioelectron ; 130: 254-261, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30771714

RESUMO

Urolithiasis commonly occurs in kidney and ureteral, and may cause local organ/tissue damage, even kidney failure. The incidence of this disease is increasing worldwide, in which calcium oxalate is the major composition forming the urinary calculus. Therefore, to monitor this disease for the prevention and treatment, measuring the oxalate in the urine is of great significance. Here, a rapid and sensitive colorimetric method was developed based on 3,3',5,5'-tetramethylbenzidine-manganese dioxide (TMB-MnO2) nanosheets for oxalate detection. MnO2 nanosheets acted as an efficient biomimetic oxidase to catalyze the reaction with TMB and oxalate. Pale yellow TMB can be oxidized to blue oxide TMB catalyzed by BSA-stabilized MnO2 nanosheets, and oxalate can selectively inhibit this reaction by consuming and reacting with MnO2 nanosheets, thus achieving the quantitative detection of oxalate. Moreover, a home-made bionic electronic-eye (E-eye) system was developed as a portable in-situ detection platform to efficiently measure the oxalate concentrations in 10 s by direct photographing. By optimizing experimental conditions, this method shows a wide linear range (7.8 µM to 250 µM) and a low detection limit (0.91 µM) for oxalate detection. Besides, this method exhibits high selectivity even with 80-fold interfering chemicals. Furthermore, the performance of the method was validated by testing the artificial urine samples, indicating its great potential for monitoring and diagnosis of urolithiasis in point-of-care applications.


Assuntos
Biônica/métodos , Técnicas Biossensoriais , Oxalatos/isolamento & purificação , Oxirredutases/química , Biomimética , Colorimetria , Glutationa/química , Humanos , Limite de Detecção , Nanoestruturas/química , Oxalatos/química , Oxirredução
19.
Biosens Bioelectron ; 130: 307-314, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30780080

RESUMO

A highly sensitive and selective glutamate biosensor using glutamate Oxidase (GlUtOx) immobilized platinum nanoparticle (PtNP) decorated multiwall carbon nanotube (MWCNTs)/polypyrrole (PPy) composite on glassy carbon electrodes (GC) is demonstrated. PtNP decorated MWCNTs (Pt-MWCNTs), PPy and Pt-MWCNTs/PPy composite were characterized by Field Emission Scanning Electron Microscope (FESEM), X-ray diffraction (XRD) and Raman analysis to confirm the formation of the nanocomposite. The glutamate Oxidase (GlUtOx) was immobilized on a GC/Pt-MWCNTs/PPy and characterized by the cyclic voltammetry (CV) and impedance spectroscopy (EIS) analysis. The fabricated L-glutamate biosensor exhibited high sensitivity (723.08 µA cm-2 mM-1) with less response time (3 s) with a detection limit of 0.88 µM. The dynamic range from 10 to 100 µM with a correlation coefficient (R2) of 0.985 was observed for the L-glutamate biosensor. The analytical recovery of added L-glutamate acid (50 and 100 µM) in human serum soup were 96.1% and 97.5% respectively. The enzyme immobilized GC/Pt-MWCNTs/PPy/GlUtOx bioelectrode lost 12.6% and 23.8% of its initial activity after 30 days when stored at - 20 °C and 4 °C respectively.


Assuntos
Técnicas Biossensoriais , Enzimas Imobilizadas/química , Ácido Glutâmico/isolamento & purificação , Polímeros/química , Espectroscopia Dielétrica , Ácido Glutâmico/química , Humanos , Limite de Detecção , Nanocompostos/química , Nanopartículas/química , Nanotubos de Carbono/química , Oxirredutases/química , Pirróis/química
20.
Bioelectrochemistry ; 127: 76-86, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30745281

RESUMO

An enzymatic biosensor based on nitric oxide reductase (NOR; purified from Marinobacter hydrocarbonoclasticus) was developed for nitric oxide (NO) detection. The biosensor was prepared by deposition onto a pyrolytic graphite electrode (PGE) of a nanocomposite constituted by carboxylated single-walled carbon nanotubes (SWCNTs), a lipidic bilayer [1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phosphoethanolamine (DOPE), 1,2-di-(9Z-octadecenoyl)-3-trimethylammonium-propane (DOTAP), 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-polyethylene glycol (DSPE-PEG)] and NOR. NOR direct electron transfer and NO bioelectrocatalysis were characterized by several electrochemical techniques. The biosensor development was also followed by scanning electron microscopy and Fourier transform infrared spectroscopy. Improved enzyme stability and electron transfer (1.96 × 10-4 cm.s-1 apparent rate constant) was obtained with the optimum SWCNTs/(DOPE:DOTAP:DSPE-PEG)/NOR) ratio of 4/2.5/4 (v/v/v), which biomimicked the NOR environment. The PGE/[SWCNTs/(DOPE:DOTAP:DSPE-PEG)/NOR] biosensor exhibited a low Michaelis-Menten constant (4.3 µM), wide linear range (0.44-9.09 µM), low detection limit (0.13 µM), high repeatability (4.1% RSD), reproducibility (7.0% RSD), and stability (ca. 5 weeks). Selectivity tests towards L-arginine, ascorbic acid, sodium nitrate, sodium nitrite and glucose showed that these compounds did not significantly interfere in NO biosensing (91.0 ±â€¯9.3%-98.4 ±â€¯5.3% recoveries). The proposed biosensor, by incorporating the benefits of biomimetic features of the phospholipid bilayer with SWCNT's inherent properties and NOR bioelectrocatalytic activity and selectivity, is a promising tool for NO.


Assuntos
Técnicas Biossensoriais/métodos , Enzimas Imobilizadas/química , Marinobacter/enzimologia , Nanotubos de Carbono/química , Óxido Nítrico/análise , Oxirredutases/química , Limite de Detecção , Bicamadas Lipídicas/química , Modelos Moleculares
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA