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1.
Int J Mol Sci ; 24(18)2023 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-37762326

RESUMO

Doublecortin-like kinase 1 (DCLK1) is a prominent kinase involved in carcinogenesis, serving as a diagnostic marker for early cancer detection and prevention, as well as a target for cancer therapy. Extensive research efforts have been dedicated to understanding its role in cancer development and designing selective inhibitors. In our previous work, we successfully determined the crystal structure of DCLK1 while it was bound to its autoinhibitory domain (AID) at the active site. By analyzing this structure, we were able to uncover the intricate molecular mechanisms behind specific cancer-causing mutations in DCLK1. Utilizing molecular dynamics simulations, we discovered that these mutations disrupt the smooth assembly of the AID, particularly affecting the R2 helix, into the kinase domain (KD). This disruption leads to the exposure of the D533 residue of the DFG (Asp-Phe-Gly) motif in the KD, either through steric hindrance, the rearrangement of electrostatic interactions, or the disruption of local structures in the AID. With these molecular insights, we conducted a screening process to identify potential small-molecule inhibitors that could bind to DCLK1 through an alternative binding mode. To assess the binding affinity of these inhibitors to the KD of DCLK1, we performed calculations on their binding energy and conducted SPR experiments. We anticipate that our study will contribute novel perspectives to the field of drug screening and optimization, particularly in targeting DCLK1.


Assuntos
Quinases Semelhantes a Duplacortina , Peptídeos e Proteínas de Sinalização Intracelular , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas Serina-Treonina Quinases/metabolismo , Carcinogênese , Mutação
2.
Luminescence ; 36(5): 1110-1116, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32706938

RESUMO

In this study, an enzyme-coupled fluorescence sensor was developed successfully for the sensitive detection of uric acid (UA) and uricase inhibitor based on graphene quantum dots (GQDs). UA was first oxidized using uricase and produced hydrogen peroxide (H2 O2 ), which could oxidize phenol to benzoquinone in the presence of horseradish peroxidase (HRP) as the catalysis. Benzoquinone is an efficient quencher and can cause fluorescence quenching of GQDs. The degree of quenching was proportional to UA concentration and was linear for the UA concentration in the ranges 0.2-14 µmol/L. The detection limit was 0.06 µmol/L for UA. In addition, the proposed sensor was further utilized for UA detection in human serum samples with satisfactory reproducibility and accuracy. The proposed strategy provided may be widely utilized to sense H2 O2 or H2 O2 generating processes in related biological environment.


Assuntos
Técnicas Biossensoriais , Grafite , Pontos Quânticos , Peroxidase do Rábano Silvestre , Humanos , Limite de Detecção , Reprodutibilidade dos Testes , Urato Oxidase , Ácido Úrico
3.
Mikrochim Acta ; 187(12): 675, 2020 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-33241461

RESUMO

A highly sensitive colorimetric sensing strategy based on enzyme@metal-organic framework (GAA@Cu-MOF) and IrO2/MnO2 nanocomposite was exploited innovatively for screening of α-glucosidase (GAA) inhibitors. IrO2/MnO2 nanocomposite exhibits excellent oxidase-mimicking activity which can directly catalyze the oxidation of 3,3,5,5,-tetramethylbenzidine (TMB) into a blue product with an absorption maximum at 652 nm. And GAA@Cu-MOF can decompose L-ascorbic acid-2-O-α-D-glucopyranosyl (AAG) to ascorbic acid (AA). The produced AA can destroy the IrO2/MnO2 nanocomposite and reduce its oxidase-like activity. However, the generation of AA is restricted when GAA inhibitors are added to the system, which allows the oxidase-like activity of the IrO2/MnO2 nanocomposite to be maintained. In view of this, a method for screening of GAA inhibitors was developed. In addition to enhancing the stability of GAA, the method can also effectively avoid the potential interference of H2O2 in the screening process of GAA inhibitors, which helps to improve the sensitivity of the method. Therefore, highly sensitive determination for acarbose and ascorbic acid are achieved with detection limits of 6.27 nM and 1.23 µM, respectively. The proposed method was successfully applied to screen potential GAA inhibitors from oleanolic acid derivatives. Graphical abstract.


Assuntos
Colorimetria/métodos , Inibidores de Glicosídeo Hidrolases/análise , Estruturas Metalorgânicas/química , Nanocompostos/química , alfa-Glucosidases/metabolismo , Acarbose/análise , Ácido Ascórbico/análise , Catálise , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Irídio/química , Limite de Detecção , Compostos de Manganês/química , Óxidos/química , alfa-Glucosidases/química
4.
Mikrochim Acta ; 186(12): 818, 2019 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-31748845

RESUMO

A turn-on ratiometric fluorescent assay is described for the determination of the activity of enzymes participating in ascorbic acid-forming reactions. Blue-emitting carbon dots (bCDs; with excitation/emission wavelength at 380/450 nm) serve as fluorescent indicator. Their fluorescence is reduced by Fe3+ ions via an inner filter effect. Yellow-emitting CDs (yCDs; with excitation/emission wavelength at 380/550 nm) serve as internal reference because their fluorescence is insensitive to Fe3+. Upon exposure to ascorbic acid (AA), Fe3+ is reduced to Fe2+. Hence, the fluorescence of the bCDs is restored. Thus, enzymes participating in AA-related reactions such as α-glucosidase (α-Glu) and alkaline phosphatase (ALP) can be determined. α-Glu activity was quantified in the range from 0.13 to 6.70 U mL-1, and ALP activity was determined between 2.0 and 130 U L-1. Endowed with excellent sensitivity, selectivity and low background signals, the method may also be used to screen the inhibitors of α-Glu and ALP. Graphical abstractSchematic representation of a redox modulated ratiometric fluorometric method based on the use of dual-color carbon dots for determination of the activity of enzymes participating in ascorbic acid-related reactions. Blue-emitting carbon dots (bCDs) serve as fluorescent indicator while yellow-emitting CDs (yCDs) serve as internal reference.


Assuntos
Fosfatase Alcalina/metabolismo , Ácido Ascórbico/metabolismo , Carbono/química , Cor , Fluorometria , Pontos Quânticos/química , alfa-Glucosidases/metabolismo , Fosfatase Alcalina/antagonistas & inibidores , Fosfatase Alcalina/sangue , Ácido Ascórbico/química , Humanos , Oxirredução , Tamanho da Partícula , Propriedades de Superfície , alfa-Glucosidases/sangue , alfa-Glucosidases/química
5.
J Enzyme Inhib Med Chem ; 33(1): 115-125, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29185359

RESUMO

Stroke is a disease of the leading causes of mortality and disability across the world, but the benefits of drugs curative effects look less compelling, intracellular calcium overload is considered to be a key pathologic factor for ischemic stroke. Gualou Guizhi decoction (GLGZD), a classical Chinese medicine compound prescription, it has been used to human clinical therapy of sequela of cerebral ischemia stroke for 10 years. This work investigated the GLGZD improved prescription against intracellular calcium overload could decreased the concentration of [Ca2+]i in cortex and striatum neurone of MCAO rats. GLGZD contains Trichosanthin and various small molecular that they are the potential active ingredients directed against NR2A, NR2B, FKBP12 and Calnodulin target proteins/enzyme have been screened by computer simulation. "Multicomponent systems" is capable to create pharmacological superposition effects. The Chinese medicine compound prescriptions could be considered as promising sources of candidates for discovery new agents.


Assuntos
Isquemia Encefálica/tratamento farmacológico , Cálcio/metabolismo , Medicamentos de Ervas Chinesas/farmacologia , Simulação de Acoplamento Molecular , Bibliotecas de Moléculas Pequenas/farmacologia , Acidente Vascular Cerebral/tratamento farmacológico , Administração Oral , Animais , Relação Dose-Resposta a Droga , Medicamentos de Ervas Chinesas/administração & dosagem , Medicamentos de Ervas Chinesas/química , Ligação Proteica/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Bibliotecas de Moléculas Pequenas/administração & dosagem , Bibliotecas de Moléculas Pequenas/química , Relação Estrutura-Atividade , Proteína 1A de Ligação a Tacrolimo/antagonistas & inibidores , Proteína 1A de Ligação a Tacrolimo/metabolismo , Tricosantina/administração & dosagem , Tricosantina/química , Tricosantina/farmacologia
6.
Electrophoresis ; 38(3-4): 486-493, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27862041

RESUMO

A new method for screening tyrosinase inhibitors from traditional Chinese medicines (TCMs) was successfully developed by capillary electrophoresis with reliable online immobilized enzyme microreactor (IMER). In addition, molecular docking study has been used for supporting inhibition interaction between enzyme and inhibitors. The IMER of tyrosinase was constructed at the outlet of the capillary by using glutaraldehyde as cross-linker. The parameters including enzyme reaction, separation of the substrate and product, and the performance of immobilized tyrosinase were investigated systematically. Because of using short-end injection procedure, the product and substrate were effectively separated within 2 min. The immobilized tyrosinase could remain 80% active for 30 days at 4°C. The Michaelis-Menten constant of tyrosinase was determined as 1.78 mM. Kojic acid, a known tyrosinase inhibitor, was used as a model compound for the validation of the inhibitors screening method. The half-maximal inhibitory concentration of kojic acid was 5.55 µM. The method was successfully applied for screening tyrosinase inhibitors from 15 compounds of TCM. Four compounds including quercetin, kaempferol, bavachinin, and bakuchiol were found having inhibitory potentials. The results obtained in this work were supported by molecular docking study.


Assuntos
Reatores Biológicos , Descoberta de Drogas/métodos , Medicamentos de Ervas Chinesas/farmacologia , Eletroforese Capilar/métodos , Enzimas Imobilizadas , Monofenol Mono-Oxigenase , Agaricales/enzimologia , Medicamentos de Ervas Chinesas/química , Enzimas Imobilizadas/antagonistas & inibidores , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Simulação de Acoplamento Molecular , Monofenol Mono-Oxigenase/antagonistas & inibidores , Monofenol Mono-Oxigenase/química , Monofenol Mono-Oxigenase/metabolismo , Reprodutibilidade dos Testes
7.
J Sep Sci ; 38(13): 2267-71, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25914271

RESUMO

A high-performance liquid chromatography method with on-line precolumn enzymatic reaction for the screening of xanthine oxidase inhibitors in natural extracts was developed. In this method, the enzymatic reaction occurred at the capillary inlet during a predetermined waiting period, after which the reaction product, uric acid, was separated and detected by liquid chromatography using ultraviolet absorption at 295 nm. Enzyme inhibition can be read out directly from the reduced peak area of uric acid in comparison to a reference chromatogram obtained in the absence of any inhibitor. In the present study, the availability of on-line precolumn enzymatic reaction with ultraviolet detection was firstly evaluated by determining the inhibitory mechanism and IC50 values of allopurinol, a commercially available positive drug. Then, the newly developed method was applied to screening of ten natural extracts from traditional Chinese medicine and as a result, the extract of Epimedium sagittatum (Sieb. et Zucc.) Maxim was found to be most positive for xanthine oxidase inhibition. The results obtained were compared with those obtained by offline enzyme assay and the effectiveness of the present method was confirmed. A rapid, low-cost, and fully automated method for xanthine oxidase inhibitor screening was proposed.

8.
Biosens Bioelectron ; 247: 115912, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38096721

RESUMO

The monitoring of acetylcholinesterase (AChE) activity and the screening of its inhibitors are significance of the diagnosis and drug therapy of nervous diseases. A metal ions-mediated signal amplification strategy was developed for the highly sensitive and multicolor assay of AChE activity and visually screening its drug inhibitors. After the specific reaction between AChE and acetylthiocholine (ATCh), the hydrolysis product thiocholine (TCh) can directly and decompose the α-FeOOH nanorods (NRs) to release amounts of Fe2+, which was regarded as Fenton reagent to efficiently catalyze H2O2 to produce ·OH. Then, the as-formed ·OH can further largely shorten the gold nanobipyramids (Au NBPs), generating a series of palpable color variations. The linear range for AChE activity was 0.01-500.0 U/L with the limit of detection as low as 0.0074 U/L. The vivid visual effects could be easily distinguished for the multicolor assay of AChE activity by naked eye in visible light. To achieve the point-of-care testing, Au NBPs were further assembled on polymeric electrospun nanofibrous films (ENFs) surface as test strips for the easy-to-use test of AChE activity by RGB values with a smartphone. Fascinatingly, this proposed strategy can be used for the visual screening AChE inhibitors or non-inhibitors. Comparing with the clinical drugs (rivastigmine tartrate, and donepezil), some natural alkaloids such as evodiamine, caffeine, camptothecin, and berberine hydrochloride were selected as inhibitor modes to confirm the drug screening capability of this method. This proposed strategy may have great potential in the other disease-related enzymatic biomarkers assay and the rapid screening of drug therapy.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Acetilcolinesterase , Peróxido de Hidrogênio , Avaliação Pré-Clínica de Medicamentos/métodos , Técnicas Biossensoriais/métodos , Inibidores da Colinesterase/farmacologia , Inibidores da Colinesterase/análise , Testes Imediatos
9.
Protein Expr Purif ; 92(1): 119-27, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24056254

RESUMO

Hsp90 has emerged as a promising target for cancer treatment. Hsp90 interacts with co-chaperone Cdc37 to mediate the conformational maturation of its kinase client proteins. Screening small molecule inhibitors targeting Hsp90/Cdc37 might be a promising strategy for further cancer therapeutic. In order to establish a recombinant protein system, the novel cloning and purification of full-length human Hsp90α and Cdc37 from BL21 (DE3) Escherichia coli is described here. In this work, we cloned and expressed recombinant NRL-Hsp90α and Cdc37-CRL that represent the full-length human Hsp90α and Cdc37 fused with the split Renilla luciferase (RL) protein fragments. We also expressed the full-length RL protein as a control for inhibitors screening. Moreover, we confirmed that the interaction proteins were able to complement split luciferase fragments and show the RL activity when substrate was added. In comparison, two mutations NRL-Hsp90α (Q133A) and Cdc37 (R167A)-CRL retained only 20% of the complemented RL activities. Six small molecule compounds were tested using this recombinant system. Very interestingly, Sulforaphane, Withaferin A, Celastrol and EGCG all decreased the complemented NRL-Hsp90α/Cdc37-CRL activities in the concentration-dependent manner. In addition, neither Sulforaphane nor Withaferin A showed non-specific inhibition on full length RL activity. However, Celastrol and EGCG showed different RL inhibition levels. The other two compounds LBH-589 and 17-AAG showed neither NRL-Hsp90α/Cdc37-CRL nor RL inhibition activities. These results indicate that purified NRL-Hsp90α and Cdc37-CRL appeared as pure, stable and active conformation, and can be used as an in vitro bioluminescence system for Hsp90/Cdc37 inhibitors screening.


Assuntos
Proteínas de Ciclo Celular/antagonistas & inibidores , Proteínas de Ciclo Celular/genética , Chaperoninas/antagonistas & inibidores , Chaperoninas/genética , Proteínas de Choque Térmico HSP90/antagonistas & inibidores , Proteínas de Choque Térmico HSP90/genética , Bibliotecas de Moléculas Pequenas/farmacologia , Animais , Proteínas de Ciclo Celular/metabolismo , Chaperoninas/metabolismo , Clonagem Molecular , Avaliação Pré-Clínica de Medicamentos/métodos , Escherichia coli/genética , Proteínas de Choque Térmico HSP90/metabolismo , Humanos , Luciferases de Renilla/genética , Luciferases de Renilla/metabolismo , Mapas de Interação de Proteínas/efeitos dos fármacos , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Renilla/enzimologia
10.
Artigo em Inglês | MEDLINE | ID: mdl-37819460

RESUMO

Covalent organic frameworks (COFs) with large specific surface areas, high porosity, good stability, and designable structure are promising carriers for immobilized enzymes. It is important to explore lipase inhibitors from natural foods as lipase inhibitors are closely related to the treatment of obesity. In this work, a carboxyl functionalized covalent organic framework (TpBD-3COOH) was prepared by solvothermal method for covalent immobilization of porcine pancreatic lipase (PPL) and obtained the enzyme-decorated COF (PPL@COF). The immobilized lipase showed wider pH and temperature tolerance with the same optimal pH and temperature of 7.5 and 50 ℃ compared to free lipase. After 6 successive reuses, the PPL@COF maintained 53.0% of its original activity. Immobilized lipase also displayed enhanced storage stability (55.4% after 14 days at 4 ℃). When p-nitrophenyl acetate was applied as the substrate, the calculated Michaelis constant was 3.57 mM and the half maximal inhibitory concentration of orlistat was 3.20 µM. Finally, the PPL@COF was used for enzyme inhibitors screening from natural foods combined with UV spectrophotometry, and Hawthorn was screened for excellent lipase inhibitory activity.

11.
Colloids Surf B Biointerfaces ; 223: 113184, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36739673

RESUMO

To quickly screen the active pharmaceutical ingredient that can be used as acetylcholinesterase inhibitors (AChEIs) to treat Alzheimer's disease, an enzyme colorimetric cellulose membrane bioactivity strip (CBS) was developed for simple and rapid screening of AChEIs. The amino group of acetylcholinesterase (AChE) undergoes Schiff base reaction with the aldehyde group on the oxidized cellulose membranes, then the AChE was covalently cross-linking on the surface of cellulose membranes, enabling the screening based on Ellman's enzyme colorimetric method. When the enzyme activity of AChE was inhibited after incubation with inhibitors, the hydrolysis of S-Acetylthiocholine iodide decreased, consequently, the 5-thio-2-nitrobenzoic acid generated by the reaction with 5,5'-dithiobis (2-nitrobenzoic acid) also decreased, leading to a decreased color intensity. In addition, CBSs had fast chromogenic time, excellent specificity, and extraordinary storage stability. Tacrine and Donepezil were used as representative inhibitors during the detection, while their IC50 and limit of detection were determined. Therefore, our work not only established a platform for effective preliminary screening of AChEIs but also inspired the further development of other cellulose membrane-based biosensors.


Assuntos
Acetilcolinesterase , Celulose , Colorimetria , Membranas , Aldeídos , Inibidores da Colinesterase
12.
Biosens Bioelectron ; 240: 115644, 2023 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-37660460

RESUMO

Recent technological advancements in testing and monitoring instrumentation have greatly contributed to the progress in cancer treatment by surgical, chemotherapeutic and radiotherapeutic interventions. However, the mortality rate still remains high, calling for the development of new treatment strategies with higher efficacy. Extensive efforts driven in this direction have included broadening of early cancer screening and applying innovative theranostic nanotechnologies. They have been supported by platforms introduced to enable the detection and monitoring of cancer biomarkers, inhibitors, and other agents, able to slow down cancer progression and prevent metastasis. Despite of the well-recognized principles of the immune checkpoint blockade, the efficacy of immunotherapy achieved so far does not meet the well-founded expectations. For a successful cancer treatment, highly sensitive, robust, and inexpensive multiplex biosensors have to be designed to aid in the biomarkers monitoring and in the development of new inhibitors. In this review, we provide an overview of the efforts undertaken to aid in the development and monitoring of anticancer immunotherapy, based on the programmed cell-death immune checkpoint (PD-1/PDL-1) blockade, by designing biosensors for the detection of relevant cancer biomarkers and their inhibitors screening. This review also emphasizes alternative targets made by exosomes carrying PD-L1 overexpressed in cancer cells and passed into the excreted exosomes. Evaluated are also novel targeted drug delivery nanocarriers, providing simultaneous biosensing, thereby contributing to the emerging immune checkpoint cancer therapy. On the basis of the current trends and the emerging technologies, future perspectives of cancer diagnostics and treatment monitoring using biosensing platforms are projected.


Assuntos
Técnicas Biossensoriais , Neoplasias , Detecção Precoce de Câncer , Receptor de Morte Celular Programada 1 , Avaliação Pré-Clínica de Medicamentos , Biomarcadores Tumorais , Neoplasias/diagnóstico , Neoplasias/tratamento farmacológico
13.
Biomedicines ; 10(7)2022 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-35884966

RESUMO

Alzheimer's disease (AD) is a neurodegenerative disease accompanied by progressive cognitive and memory dysfunction due to disruption of normal electrotonic properties of neurons and neuronal loss. The Na,K-ATPase interaction with beta amyloid (Aß) plays an important role in AD pathogenesis. It has been shown that Na,K-ATPase activity in the AD brain was significantly lower than those in age-matched control brain. The interaction of Aß42 with Na,K-ATPase and subsequent oligomerization leads to inhibition of the enzyme activity. In this study interaction interfaces between three common Aß42 isoforms, and different conformations of human Na,K-ATPase (α1ß1) have been obtained using molecular modeling, including docking and molecular dynamics (MD). Interaction sites of Na,K-ATPase with Aß42 are localized between extracellular parts of α- and ß- subunits and are practically identical for Na,K-ATPase at different conformations. Thermodynamic parameters for the formation of Na,K-ATPase:Aß42 complex at different conformations acquired by isothermal titration calorimetry (ITC) are similar, which is in line with the data of molecular modeling. Similarity of Na,K-ATPase interaction interfaces with Aß in all conformations allowed us to cross-screen potential inhibitors for this interaction and find pharmaceutical compounds that could block it.

14.
J Pharm Biomed Anal ; 203: 114228, 2021 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-34182409

RESUMO

Ten-eleven translocation protein 1 (TET1) is one member of TET proteins family which plays a key role in dynamic DNA methylation-demethylation process. Herein, a novel biosensor was constructed for TET1 detection and its inhibitors screening utilizing restriction digestion of endonuclease enzyme MspI. Half-methylated oligonucleotide (5mC DNA) was used as target and Ru(NH3)63+ as electrochemical signal probe. After the treatment by TET1 and T4 ß-glucosyltransferase (T4 ß-GT), target oligonucleotide would not be recognized and digested. If there was no TET1, the target would be digested and the response of biosensor decreased greatly. The current difference of biosensor with and without the incubation with TET1 was therefore dependent on the concentration of TET1. To increase sensitivity of the biosensor, nanostructured film at electrode surface and nanoparticles modified oligonucleotides were employed as signal amplification elements for Ru(NH3)63+ recycling. Finally, this biosensor showed high performance with a wide linear range of TET1 concentration from 3.5-21 ng/µL and a low detection limit of 0.33 ng/µL, which is superior to other existing methods. The inhibition effects of Bobcat339 on TET1 was successfully proved by our biosensor with an IC50 of 38 µM. Not only that, but the feasibility of the biosensor for inhibitors screening was evaluated and further confirmed by other compounds including two anticancer drugs and three active ingredients of traditional Chinese medicine.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , DNA , Metilação de DNA , Técnicas Eletroquímicas , Oxirredução
15.
J Chromatogr A ; 1615: 460711, 2020 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-31759638

RESUMO

With the increasing demand for lipase inhibitors and new drugs used in the clinical treatment of obesity, it is of great significance to screen lipase inhibitors from traditional Chinese medicines (TCMs) via capillary electrophoresis. In this work, Fe3O4@TiO2 nanoparticles was fabricated by solvothermal method and employed as an improved magnetic support to immobilize lipase through electrostatic interaction. By the method of transmission electron microscopy, fourier transform infrared spectroscopy and X-ray diffraction, the magnetic nanoparticles were characterized. The immobilized enzyme possessed advantages of a wider range for pH and temperature endurance, better storage stability and reusability. The kinetics performances of the immobilized lipase were studied. When p-Nitrophenyl palmitate (pNPP) was used as enzyme substrate, the Michaelis-Menten constant was calculated to be 2.51 mM and its inhibition constant for Orlistat was ascertained to be 13.41 µM. Ultimately, the established method was applied to lipase inhibitors screening from 6 Tibetan medicines with lipase inhibitory activity and Oxytropis falcate Bunge was screened out for its supreme lipase inhibitory activity. 11 compounds in the Oxytropis falcate Bunge were further screened, five compounds exhibited similar inhibitory activity to Orlistat, and one compound (kaempferol) presented better inhibitory activity than Orlistat, which is the most commonly used drugs to treat obesity in clinic. This work not only developed a method for new anti-obesity drugs discovery, but also provided inspiration for exploring new medicinal value of the TCMs.


Assuntos
Avaliação Pré-Clínica de Medicamentos/métodos , Inibidores Enzimáticos/isolamento & purificação , Lipase/antagonistas & inibidores , Medicina Tradicional Chinesa , Eletroforese Capilar , Enzimas Imobilizadas/química , Concentração de Íons de Hidrogênio , Ferro/química , Cinética , Magnetismo , Nanopartículas Metálicas/química , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Tibet , Titânio/química , Difração de Raios X
16.
Talanta ; 205: 120126, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31450397

RESUMO

Inspired by the porous and fibrous structure of commercially available bamboo, herein we created an l-glutaminase enzyme reactor based on bamboo sticks. The enzyme was immobilized onto the bamboo sticks through a glutaraldehyde modification to achieve covalent bonding. The enzymatic hydrolysis efficiency of the prepared l-glutaminase@bamboo sticks based porous enzyme reactor was evaluated by chiral ligand exchange capillary electrochromatography using l-glutamine as the substrate. l-glutaminase@bamboo exhibited improved enzymatic hydrolysis performances, including high hydrolysis efficiency (maximum rate Vmax: two fold higher than the free enzyme), prolonged stability (14 days) and good reusability. l-Glutaminase@bamboo sticks also expanded application capability in pharmaceutical industry in enzyme inhibitor screening. These excellent properties could be attributed to the micropores of bamboo sticks, which led to the fast enzymatic kinetics. The results suggest that the pores of bamboo sticks played an important role in the proposed enzyme reactor during the hydrolysis of l-glutamine and l-glutaminase inhibitor screening.


Assuntos
Avaliação Pré-Clínica de Medicamentos/métodos , Inibidores Enzimáticos/farmacologia , Glutaminase/antagonistas & inibidores , Glutaminase/metabolismo , Poaceae/química , Estabilidade Enzimática , Enzimas Imobilizadas/antagonistas & inibidores , Enzimas Imobilizadas/química , Enzimas Imobilizadas/metabolismo , Glutaminase/química , Glutaral/metabolismo , Cinética , Porosidade , Propriedades de Superfície
17.
ACS Sens ; 4(5): 1222-1229, 2019 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-31001975

RESUMO

The development of effective detection methods for hexosaminidase is of great importance for the rapid screening of potential inhibitors in vitro and for the early diagnosis of related diseases ex vivo. In this study, the activatable fluorescent probes that are based on naphthalimide decorated with ethylene glycol units were synthesized using N-acetyl-ß-d-glucosaminide as a hexosaminidase-responsive group. When exposed to this enzyme, the glucoside-linked naphthalimide moiety of 1c can be cleaved quickly with significant changes in both color (from colorless to yellow) and fluorescence (from blue to green). Probe 1c shows better water-solubility and fluorescence properties than common substrate 4-methylumbelliferyl N-acetyl-ß-d-glucosaminide. Furthermore, the response mechanism of 1c to hexosaminidase was evaluated using HPLC analysis and TD-DFT calculations. Molecular docking was performed to investigate the interaction mode. In addition, 1c has successfully achieved the straightforward rapid discovery of effective hexosaminidase inhibitors. Fluorescence imaging experiments indicate that 1c has good cell safety and can be employed as a useful tool for detecting intracellular hexosaminidase activity.


Assuntos
Ensaios Enzimáticos/métodos , Hexosaminidases/química , Hexosaminidases/metabolismo , Espaço Intracelular/metabolismo , Naftalimidas/química , Imagem Óptica/métodos , Benzeno/química , Domínio Catalítico , Linhagem Celular Tumoral , Inibidores Enzimáticos/farmacologia , Glicosilação , Hexosaminidases/antagonistas & inibidores , Humanos , Cinética , Simulação de Acoplamento Molecular , Polietilenoglicóis/química
18.
Talanta ; 182: 600-605, 2018 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-29501199

RESUMO

Alanine aminotransferase (ALT) plays significant role in biological and clinical research. In this study, a unique ALT enzyme reactor based on multifunctional polymer@magnetic nanoparticles has been constructed for the first time and the enzymolysis efficiency has been evaluated by chiral ligand exchange capillary electrophoresis technique. Poly(N-acryloxysuccinimide) has been synthesized by reversible addition-fragmentation chain transfer polymerization method and immobilized on the magnetic nanoparticles via the succinimide group in the polymer. Interestingly, the enzyme also could easily react with the succinimide group, which enables of ALT covalent bonding onto the polymer. The enzyme amount immobilized and the immobilization time have been investigated. Comparing with free ALT in solution (Vmax of free enzyme = 0.6 mM min-1), the resultant enzyme reactor has exhibited good reusability and stability, and displayed about five times enhanced enzymolysis efficiency with L-alanine as the substrate (Vmax of enzyme reactor = 3.4 mM min-1). Furthermore, the prepared enzyme reactor has been applied in ALT inhibitors screening. The enzyme reactors based on the multifunctional polymer@magnetic nanoparticles have depicted great potential in anti-liver drugs development, liver diseases study and ALT related biological process inspect.


Assuntos
Alanina Transaminase/química , Alanina/química , Reatores Biológicos , Enzimas Imobilizadas/química , Nanopartículas de Magnetita/química , Acrilatos/química , Alanina Transaminase/antagonistas & inibidores , Biocatálise , Eletroforese Capilar/métodos , Ensaios Enzimáticos , Inibidores Enzimáticos/química , Enzimas Imobilizadas/antagonistas & inibidores , Reutilização de Equipamento , Ensaios de Triagem em Larga Escala , Humanos , Cinética , Nanopartículas de Magnetita/ultraestrutura , Polimerização , Succinimidas/química
20.
Talanta ; 165: 251-257, 2017 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-28153250

RESUMO

In this work, a unique D-amino acid oxidase reactor for enhanced enzymolysis efficiency is presented. A kind of magnetic polymer matrices, composed of iron oxide nanoparticles and porous polymer membrane (poly styrene-co-maleic anhydride), was prepared. With covalent bonding D-Amino acid oxidase on the surface of the matrices and characterization of scanning electron microscope and vibrating sample magnetometer, it demonstrated that the membrane enzyme reactor was successfully constructed. The enzymolysis efficiency of the enzyme reactor was evaluated and the apparent Michaelis-Menten constants of D-Amino acid oxidase were determined (Km was 1.10mM, Vmax was 23.8mMmin-1) by a chiral ligand exchange capillary electrophoresis protocol with methionine as the substrate. The results indicated that the enzyme reactor could exhibit good stability and excellent reusability. Importantly, because the enzyme and the substrate could be confined into the pores of the matrices, the enzyme reactor displayed the improved enzymolysis efficiency due to the confinement effect. Further, the prepared enzyme reactor was applied for D-Amino acid oxidase inhibitors screening. It has displayed that the proposed protocol could pave a new way for fabrication of novel porous polymer membrane based enzyme reactors to screen enzyme inhibitors.


Assuntos
Reatores Biológicos , D-Aminoácido Oxidase/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Enzimas Imobilizadas/química , Ensaios de Triagem em Larga Escala/métodos , Magnetismo , Polímeros/química , Avaliação Pré-Clínica de Medicamentos , Enzimas Imobilizadas/metabolismo , Humanos , Cinética , Ligantes , Membranas , Metionina/metabolismo , Polímeros/metabolismo , Porosidade
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