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1.
J Cell Mol Med ; 28(2): e18045, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38011007

RESUMO

NK cells play a role in various cancers, but their role in head and neck squamous cell carcinoma (HNSCC) still needs to be explored. All public data are obtained from the Cancer Genome Atlas Program (TCGA) database. All analysis was performed using specific packages in R software. In our study, we quantified the immune microenvironment of HNSCC through multiple algorithms. Next, we identified NK cell-associated genes by quantifying NK cells, including SSNA1, TRIR, PAXX, DPP7, WDR34, EZR, PHLDA1 and ELOVL1. Then, we explored the single-cell expression pattern of these genes in the HNSCC microenvironment. Univariate Cox regression analysis indicated that the EZR, PHLDA1 and ELOVL1 were related to the prognosis of HNSCC patients. Following this, we selected EZR for further analysis. Our results showed that the patients with high EZR expression might have a poor prognosis and worse clinical features. Biological enrichment analysis showed that EZR is associated with many oncogenic pathways and a higher tumour stemness index. Meanwhile, we found that EZR can remodel the immune microenvironment of HNSCC. Moreover, we noticed that EZR could affect the immunotherapy and specific drug sensitivity, making it an underlying clinical target. In summary, our results can improve the understanding of NK cell in HNSCC. Meanwhile, we identified EZR as the underlying clinical target of HNSCC.


Assuntos
Carcinoma , Neoplasias de Cabeça e Pescoço , Humanos , Carcinoma de Células Escamosas de Cabeça e Pescoço/genética , Células Matadoras Naturais , Neoplasias de Cabeça e Pescoço/genética , Imunidade , Microambiente Tumoral/genética , Proteínas de Transporte
2.
Zhongguo Zhong Yao Za Zhi ; 49(6): 1579-1586, 2024 Mar.
Artigo em Zh | MEDLINE | ID: mdl-38621942

RESUMO

This study aims to investigate the effects of Gualou Xiebai Banxia Decoction(GXBD) on type 2 diabetes mellitus(T2DM) combined with acute myocardial infarction(AMI) in rats via chemerin/chemokine-like receptor 1(CMKLR1)/peroxisome proliferator-activated receptor α(PPARα) signaling pathway, and to explore the mechanism of GXBD in alleviating glucose and lipid metabolism disorders. The SD rats were randomized into control, model, positive control, and low-and high-dose GXBD groups. The rat model of T2DM was established by administration with high-fat emulsion(HFE) by gavage and intraperitoneal injection with streptozotocin, and then coronary artery ligation was performed to induce AMI. The control and model groups were administrated with the equal volume of normal saline, and other groups were administrated with corresponding drugs by gavage. Changes in relevant metabolic indicators were assessed by ELISA and biochemical assays, and the protein levels of chemerin, CMKLR1, and PPARα in the liver, abdominal fat, and heart were determined by Western blot. The results showed that GXBD alleviated the myocardial damage and reduced the levels of blood lipids, myocardial enzymes, and inflammatory cytokines, while it did not lead to significant changes in blood glucose. Compared with the model group, GXBD down-regulated the expression of chemerin in peripheral blood and up-regulated the expression of cyclic adenosine monophosphate(cAMP) and protein kinase A(PKA) in the liver. After treatment with GXBD, the protein levels of chemerin and CMKLR1 in the liver, abdominal fat, and heart were down-regulated, while the protein levels of PPARα in the liver and abdominal fat were up-regulated. In conclusion, GXBD significantly ameliorated the disorders of glycolipid metabolism in the T2DM-AMI model by regulating the chemerin/CMKLR1/PPARα signaling pathway to exert a protective effect on the damaged myocardium. This study provides a theoretical basis for further clinical study of GXBD against T2DM-AMI and is a manifestation of TCM treatment of phlegm and turbidity causing obstruction at the protein level.


Assuntos
Diabetes Mellitus Tipo 2 , Medicamentos de Ervas Chinesas , Infarto do Miocárdio , Ratos , Animais , PPAR alfa/genética , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Ratos Sprague-Dawley , Transdução de Sinais , Infarto do Miocárdio/tratamento farmacológico , Quimiocinas
3.
Mediators Inflamm ; 2022: 2124230, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36262547

RESUMO

Several studies have demonstrated that exercise preconditioning is an effective means of alleviating poststroke cognitive impairment (PSCI). Mechanisms of regulating cognitive function have not been fully elucidated. Herein, the present study is aimed at exploring the effect of the microbiota-gut-inflammasome-brain axis in the process of exercise preconditioning moderating cognitive impairment after ischemic stroke. We observed that exercise preconditioning decreased infarct size, reduced the degree of neuronal damage, and alleviated cognitive impairment in mice with ischemic stroke. In addition, exercise preconditioning also reduced the expression of inflammatory cytokines, as well as NLRP3, Caspase-1, IL-18, and IL-1ß protein expressions. Ischemic stroke could downregulate the abundance of Roseburia while increasing the abundance of the Helicobacter at the level of genus. As a comparison, exercise preconditioning increased the abundance of the Lactobacillus, which was beneficial for mice at the genus level. In conclusion, exercise preconditioning can improve cognitive dysfunction after ischemic stroke through alleviating inflammation and regulating the composition and diversity of the gut microbiota, which might provide a new strategy for the prevention of PSCI.


Assuntos
Disfunção Cognitiva , Microbioma Gastrointestinal , AVC Isquêmico , Animais , Camundongos , Microbioma Gastrointestinal/fisiologia , Interleucina-18 , Inflamassomos , Proteína 3 que Contém Domínio de Pirina da Família NLR , Disfunção Cognitiva/terapia , Inflamação/metabolismo , Citocinas/metabolismo , Caspase 1
4.
Pak J Pharm Sci ; 31(5): 1951-1957, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30150194

RESUMO

In order to investigate the anti-inflammatory activity of flavonoids, phenolic acids, and alkaloids from the flowers of Trollius chinensis, some representative compounds, namely, orientin, 2"-O-ß-L-galactopyranosylorientin, vitexin, quercetin, isoquercetin, luteolin, veratric acid, proglobeflowery acid, trollioside, and trolline were selected to study their inhibitory effects against LPS-induced NO, IL-6, and TNF-ß release in RAW264.7 cells. At the higher concentration, both phenolic acids and flavonoids inhibited the production of NO, whereas only phenolic acids showed this effect at the lower concentration. Although trolline had stronger cytotoxicity, it exhibited a potential effect of decreasing NO production induced by LPS in the non-toxic concentration range. In addition, all tested compounds decreased the production of IL-6 and TNF-a by almost 50% at both the higher and lower concentrations. It is concluded that the anti-inflammatory activity of the phenolic acids is stronger than that of the flavonoids.


Assuntos
Anti-Inflamatórios/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Flores , Extratos Vegetais/farmacologia , Ranunculaceae , Ácido Vanílico/análogos & derivados , Alcaloides/isolamento & purificação , Alcaloides/farmacologia , Animais , Anti-Inflamatórios/isolamento & purificação , Apigenina/isolamento & purificação , Apigenina/farmacologia , Sobrevivência Celular/fisiologia , Relação Dose-Resposta a Droga , Flavonoides/isolamento & purificação , Flavonoides/farmacologia , Glucosídeos/isolamento & purificação , Glucosídeos/farmacologia , Camundongos , Extratos Vegetais/isolamento & purificação , Células RAW 264.7 , Ácido Vanílico/isolamento & purificação , Ácido Vanílico/farmacologia
6.
J Asian Nat Prod Res ; 17(1): 89-106, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25296190

RESUMO

Liver is the largest metabolic organ for a wide range of endogenous and exogenous compounds and plays a crucial part in the pharmacokinetics and pharmacodynamics through various metabolic reactions. This review provides a progressive description of hepatic metabolism of herbal drugs with respect to metabolic types and investigational methods. In addition, the problems encountered during the research process are discussed.


Assuntos
Medicina Herbária , Fígado/metabolismo , Humanos , Estrutura Molecular
7.
Med Sci Monit ; 20: 945-52, 2014 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-24911067

RESUMO

BACKGROUND: Accumulating epidemiological evidence shows that life event stressors are major vulnerability factors for psychiatric diseases such as major depression. It is also well known that the resident intruder paradigm (RIP) results in aggressive behavior in male rats. However, it is not known how resident intruder paradigm-induced aggression affects depressive-like behavior in isolated male rats subjected to chronic mild stress (CMS), which is an animal model of depression. MATERIAL AND METHODS: Male Wistar rats were divided into 3 groups: non-stressed controls, isolated rats subjected to the CMS protocol, and resident intruder paradigm-exposed rats subjected to the CMS protocol. RESULTS: In the sucrose intake test, ingestion of a 1% sucrose solution by rats in the CMS group was significantly lower than in control and CMS+RIP rats after 3 weeks of stress. In the open-field test, CMS rats had significantly lower open-field scores compared to control rats. Furthermore, the total scores given the CMS group were significantly lower than in the CMS+RIP rats. In the forced swimming test (FST), the immobility times of CMS rats were significantly longer than those of the control or CMS+RIP rats. However, no differences were observed between controls and CMS+RIP rats. CONCLUSIONS: Our data show that aggressive behavior evoked by the resident intruder paradigm could relieve broad-spectrum depressive-like behaviors in isolated adult male rats subjected to CMS.


Assuntos
Agressão/psicologia , Comportamento Animal , Depressão/psicologia , Estresse Psicológico/psicologia , Animais , Comportamento de Escolha , Masculino , Ratos Wistar , Natação , Aumento de Peso
8.
Sci Rep ; 14(1): 2307, 2024 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-38280923

RESUMO

In recent years, research on ventilating tunnels has become increasingly important. However, the impact of external disturbances on ventilating systems has been largely ignored. To address this issue of frequent airflow fluctuations caused by external perturbations, which cannot be fully compensated using conventional control methods, this study proposes a perturbation-compensated ventilation control approach. A disturbance compensator is developed by incorporating the tunnel's airflow velocity and the number of jet fan start-stop events as input parameters. By compensating for external disturbances, the disturbance to the system is reduced. The Simulink model of the tunnel controller was used for simulation experiments. The compensator demonstrated good tracking results in comparison experiments with different disturbances. The ventilation approach based on disturbance compensator is capable of regulating the fluctuation of CO concentration within a justifiable range compared to using PID control and ADRC. This not only improves the stability of the entire control system but also significantly prolongs the service life of the jet fan by reducing the frequency of start-stop cycles.

9.
Front Pharmacol ; 14: 1133655, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36959857

RESUMO

A series of novel ferulic acid derivatives were designed and synthesized, and the twenty-one compounds were evaluated for their antiviral activities against Respiratory syncytial virus (RSV), herpes simplex virus type 1 (HSV-1), and enterovirus type 71 (EV71). These derivatives with the core structure of diphenyl acrylic acids had cis-trans isomers, which were confirmed by 1H NMR, HPLC, and UV-vis spectra for the first time. The A5 had a selective effect against RSV but no work on herpes simplex virus type 1 and enterovirus type 71, which showed a therapeutic index (TI) of 32 and was significantly better than ferulic acid. The A5 had no scavenging effect on free radicals, but the A2 as the degradation of A5 showed an obvious scavenging effect on DPPH· and ABTS+·. In addition, the A5 had no toxicity to endothelial cells and even showed a proliferative effect. Therefore, the A5 is worth further optimizing its structure as a lead compound and investigating the mechanism of inhibiting Respiratory syncytial virus.

10.
Aging (Albany NY) ; 14(19): 7877-7889, 2022 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-36202115

RESUMO

This study aims to explore the role of hyperlipidemia in the mobilization of bone marrow (BM) endothelial progenitor cells (EPCs) induced by acute myocardial ischemia (AMI). To establish the hyperlipidemia complicated with AMI (HL-AMI) model, SD rats were intragastrically administered the high-fat emulsion for 4 weeks. Then their left anterior descending arteries were ligated. Rats in each group were randomly subdivided into seven subgroups. During 1st ~ 7th day following AMI modeling, rats in 1st ~ 7th subgroups were selected to be phlebotomized from their celiac artery after being anesthetized by pentobarbitone in turn. The quantity of circulating EPCs (CEPCs) was detected by flow cytometry, the expression of VEGF, eNOS, NO, MMP-9 in myocardial tissue was analyzed by western blot, and their plasma level was assayed by ELISA. Dynamic curves were plotted using these data. Within 7 days following AMI, compared with the AMI rats, in the HL-AMI rats, the myocardial infarct size, the plasma activity of CK, CK-MB, and the collagen deposition all remained at the higher levels; meanwhile, these rats showed more significant decreases in the count of CEPCs, the plasma level of VEGF etc., and their expression in myocardial tissue (P < 0.05 or P < 0.01). Our study showed that hyperlipidemia may attenuate the mobilization of BM EPCs induced by AMI via VEGF/eNOS/NO/MMP-9 signal pathway, which might partly account for hyperlipidemia hampering the repairs of AMI-induced cardiac injury.


Assuntos
Células Progenitoras Endoteliais , Hiperlipidemias , Isquemia Miocárdica , Animais , Ratos , Colágeno , Emulsões , Células Progenitoras Endoteliais/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Pentobarbital , Ratos Sprague-Dawley , Fator A de Crescimento do Endotélio Vascular/metabolismo
11.
Neurosci Lett ; 770: 136400, 2022 01 23.
Artigo em Inglês | MEDLINE | ID: mdl-34923041

RESUMO

Nuclear factor erythroid 2-related factor 2 (Nrf2) plays an important role in neuroprotection and recover. Our studies have showed that endoplasmic reticulum (ER) stress-induced apoptosis aggravates secondary damage following traumatic brain injury (TBI). Whether Nrf2 involved in ER stress and ER stress-mediated apoptosis is not clearly investigated. This present study explored the effect of Nrf2 knockout on ER stress and ER stress-induced apoptosis in TBI mice. A lateral fluid percussion injury (FPI)model of TBI was built based on Nrf2 knockout (Nrf2(-/-)) mice and wild-type (Nrf2(+/+)) mice, and the expressions of marker proteins of ER stress and ER stress-induced apoptosis were checked at 24 h following TBI. We found that Nrf2(-/-) mice presented more severe neurological deficit, brain edema and neuronal cell apoptosis compared with Nrf2(+/+) mice. And, the TBI Nrf2(-/-) mice were significantly increased expression of marker proteins of ER stress and ER stress-induced apoptotic pathway including glucose regulated protein (GRP78), protein kinase RNA-like ER kinase (PERK), inositol requiring enzyme (IRE1), activating transcription factor 6 (ATF6), C/EBP homologous protein (CHOP), caspase-12 and caspase-3, compared with that in WT mice. These results suggest that Nrf2 could ameliorate TBI-induced second brain injury partly through ER stress signal pathway.


Assuntos
Apoptose , Lesões Encefálicas Traumáticas/metabolismo , Estresse do Retículo Endoplasmático , Fator 2 Relacionado a NF-E2/metabolismo , Fator 6 Ativador da Transcrição/metabolismo , Animais , Lesões Encefálicas Traumáticas/genética , Chaperona BiP do Retículo Endoplasmático/metabolismo , Mutação com Perda de Função , Masculino , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Endogâmicos ICR , Fator 2 Relacionado a NF-E2/genética , Proteínas Serina-Treonina Quinases/metabolismo , Fator de Transcrição CHOP/metabolismo , eIF-2 Quinase/metabolismo
12.
Electrophoresis ; 32(21): 3034-41, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21997574

RESUMO

The effect of acidic pH on the translocation of single-stranded DNA through the α-hemolysin pore is investigated. Two significantly different types of events, i.e. deep blockades and shallow blockades, are observed at low pH. The residence times of the shallow blockades are not significantly different from those of the DNA translocation events obtained at or near physiological pH, whereas the deep blockades have much larger residence times and blockage amplitudes. With a decrease in the pH of the electrolyte solution, the percentage of the deep blockades in the total events increases. Furthermore, the mean residence time of these long-lived events is dependent on the length of DNA, and also varies with the nucleotide base, suggesting that they are appropriate for use in DNA analysis. In addition to being used as an effective approach to affect DNA translocation in the nanopore, manipulation of the pH of the electrolyte solution provides a potential means to greatly enhance the sensitivity of nanopore stochastic sensing.


Assuntos
Transporte Biológico Ativo , DNA de Cadeia Simples/metabolismo , Proteínas Hemolisinas/metabolismo , Modelos Biológicos , Nanoporos , DNA de Cadeia Simples/química , Técnicas Eletroquímicas , Eletrólitos/química , Proteínas Hemolisinas/química , Concentração de Íons de Hidrogênio , Cloreto de Sódio
13.
Chin J Nat Med ; 19(3): 161-169, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33781449

RESUMO

Gualou-Xiebai-Banxia decoction has a long history of medical use for treating cardiovascular diseases in China. In this study, we investigated the protective effect and underlying mechanisms GXB in type II diabetes with acute myocardial ischemia (T2DM-AMI) rats. We hypothesized that GXB may display its protective effect on T2DM-AMI by reducing endothelial progenitor cells (EPCs) apoptosisviaactivating PI3K (phosphatidyl inositol 3-kinase)/Akt (serine/threonine protein kinase B)/eNOS (endothelial nitric oxide synthase) signaling. Rats were challenged with a high-fat diet and intraperitoneal injection of streptozotocin to induce a model of type II diabetes mellitus (T2DM) and coronary ligation to induce acute myocardial infarction (AMI). Changes in metabolites were assessed via enzyme-linked immunoassay and biochemical examination. The number and apoptosis rate of EPCs in peripheral blood were detected by flow cytometry. Target mRNAs and proteins in EPCs were analyzed by RT-PCR and Western blot analysis. The results demonstrated that GXB treatment decreased T2DM-AMI-associated changes in plasma fasting blood glucose, muscular enzymes, and blood lipids, and reduced oxidative stress. Furthermore, EPC apoptosis was increased in T2DM-AMI rats and was associated with decreased mRNA and protein levels of PI3K, Akt, and eNOS compared to the controls. Conversely, T2DM-AMI rats treated with GXB exhibited more circulating EPCs and downregulated levels of cell apoptosis, combined with increased mRNA and protein levels of PI3K, Akt, and eNOS compared to those of untreated T2DM-AMI rats. Our study showed that GXB treatment mitigated EPC apoptosis and promoted PI3K/Akt/eNOS signaling in T2DM-AMI rats.


Assuntos
Diabetes Mellitus Tipo 2 , Medicamentos de Ervas Chinesas/farmacologia , Infarto do Miocárdio , Animais , Apoptose , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/genética , Infarto do Miocárdio/tratamento farmacológico , Infarto do Miocárdio/genética , Óxido Nítrico Sintase Tipo III/genética , Óxido Nítrico Sintase Tipo III/metabolismo , Estresse Oxidativo , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos
14.
Genes Brain Behav ; 19(5): e12649, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32129566

RESUMO

According to traditional Chinese medicine, lily bulb and Rehmannia decoction (LBRD) is a specialized formula for the treatment of "lily disease", the symptoms of which resemble the clinical manifestations of major depression. However, the molecular basis of the antidepressant mechanism of LBRD and the quality marker ingredients of LBRD remain unclear. This study aimed to investigate the quality marker ingredients of LBRD and to show the molecular mechanism of its antidepressant activities. In this study, we adopted the chronic unpredicted mild stress paradigm to construct a depression model. High-performance liquid chromatography (HPLC) was used to determine the levels of the main markers in LBRD. The underlying mechanism of LBRD was explored by measuring neurotransmitter and cytokine levels using enzyme-linked immunosorbent assay, and by quantifying differentially expressed gene (DEG) of transcriptome in the medial prefrontal cortex (mPFC) tissue through RNA sequencing. HPLC results showed that the average levels of quality marker ingredients of LBRD (ferulic acid, dioscin, verbascoside and catalpol) were 0.00079%, 0.00039%, 0.7% and 1.6% (w/w), respectively. LBRD intervention significantly attenuated the depressive phenotype compared with that in the depressed group. LBRD treatment altered the enriched DEGs in the signaling pathways of γ-aminobutyric acid (GABA) and glutamate neurotransmitter, synaptic plasticity and axon guidance, circadian rhythm and neural-immunity. GABAergic and glutamatergic synapses as well as brain-derived neurotrophic factor (BDNF)/TrkB-dependent phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin-1 (mTOR1), might be the main signaling pathways underlying the multi-target therapeutic effects of LBRD against depression.


Assuntos
Antidepressivos/farmacologia , Depressão/genética , Extratos Vegetais/farmacologia , Córtex Pré-Frontal/efeitos dos fármacos , Estresse Psicológico/genética , Transcriptoma , Animais , Antidepressivos/química , Fator Neurotrófico Derivado do Encéfalo/genética , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Citocinas/metabolismo , Depressão/tratamento farmacológico , Depressão/metabolismo , Lilium/química , Masculino , Medicina Tradicional Chinesa , Camundongos , Camundongos Endogâmicos C57BL , Neurotransmissores/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Extratos Vegetais/química , Córtex Pré-Frontal/metabolismo , Rehmannia/química , Estresse Psicológico/tratamento farmacológico , Estresse Psicológico/metabolismo
15.
J Am Chem Soc ; 131(18): 6324-5, 2009 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-19368382

RESUMO

Here we report a rapid, label-free method for monitoring peptide cleavage. Monitoring peptide translocation through an engineered ion channel in the absence and the presence of an enzyme allowed quantitative chemical kinetics information on enzymatic processes to be obtained. In addition to its potential application in disease diagnostics and drug discovery, this peptide/protein cleavage approach is envisioned for further development as a novel rapid, label-free protein sequencing technique.


Assuntos
Enzimas/metabolismo , Peptídeos/metabolismo , Hidrólise , Canais Iônicos/síntese química , Cinética , Análise de Sequência de Proteína/métodos
16.
Anal Chem ; 81(1): 460-4, 2009 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-19055422

RESUMO

We report a rapid and sensitive stochastic nanopore sensing method for the detection of monovalent cations and liquid explosive components and their sensitizers. The sensing element is a wild-type alpha-hemolysin protein pore with boromycin as a molecular adaptor, while a solution containing an ionic liquid was used as the background electrolyte. The analyte-boromycin complexes showed significantly different signatures. Specifically, their event mean dwell times and amplitudes were sufficiently distinct to permit the convenient differentiation and even simultaneous detection of liquid explosive components in aqueous environments. In addition, the results also demonstrate that the usage of specific ionic liquid salt solutions instead of NaCl or KCl solution as supporting electrolyte provides a useful means to greatly enhance the sensitivity of the nanopore for some analytes in stochastic sensing.

17.
J Phys Chem B ; 113(11): 3572-8, 2009 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-19231820

RESUMO

Peptides play important roles in a variety of biological processes. Here, we studied the transport of peptides containing mainly aromatic amino acids in protein pores engineered with aromatic binding sites. With an increase in the length of the peptide, both the event mean dwell time and the current blockage amplitude increased. The dissociation rate constants k(off) decreased significantly, while the association rate constants k(on) decreased slowly as the peptide length increased. Thus, the overall reaction formation constants K(f), and hence the binding affinities of various peptides to the protein pore, are largely dependent upon the dissociation rate constants rather than the association rate constants. Furthermore, in a protein channel modified with aromatic binding sites, aromatic amino acid components contributed more to the dwell time and current blockage of the events than other types of amino acids, although the van der Waals volumes of amino acids also affected the event signatures. The effect of protein structure on peptide translocation was also investigated. With more aromatic binding sites engineered inside the lumen of the protein pore, a stronger binding affinity between peptides and the pore was observed. With the much enhanced resolution of the engineered protein pore, a series of short peptides, including those differing by a single amino acid, was successfully differentiated and simultaneously quantified. In addition to providing a rapid and cost-effective method for the peptide detection, the engineered protein pore approach offers the potential for peptide and protein sequencing.


Assuntos
Transporte Biológico Ativo/fisiologia , Proteínas de Escherichia coli/química , Proteínas Hemolisinas/química , Peptídeos/metabolismo , Engenharia de Proteínas , Peptídeos beta-Amiloides/química , Proteínas de Escherichia coli/genética , Proteínas Hemolisinas/genética , Indicadores e Reagentes , Cinética , Peptídeos/genética , Fosfatidilcolinas/química , Porinas/química , Porinas/genética , Ligação Proteica
18.
J Phys Chem B ; 113(40): 13332-6, 2009 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-19736966

RESUMO

One of the key challenges to nanopore DNA sequencing is to slow down DNA translocation. Here, we report that the translocation velocities of various DNA homo- and copolymers through protein pores could be significantly decreased by using electrolyte solutions containing organic salts. Using a butylmethylimidazolium chloride (BMIM-Cl) solution instead of the commonly used KCl solution, DNA translocation rates on the order of hundreds of microseconds per nucleotide base were achieved. The much enhanced resolution of the nanopore coupled with different event blockage amplitudes produced by different nucleotides permits the convenient differentiation between various DNA molecules.


Assuntos
DNA , Nanoestruturas , Compostos Orgânicos/química , Sais/química , Transporte Biológico/fisiologia , Cloretos/química , DNA/química , DNA/metabolismo , Imidazolinas/química , Bicamadas Lipídicas/química
19.
Biophys J ; 94(4): 1267-75, 2008 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-17993487

RESUMO

Salt plays a critical role in the physiological activities of cells. We show that ionic strength significantly affects the kinetics of noncovalent interactions in protein channels, as observed in stochastic studies of the transfer of various analytes through pores of wild-type and mutant alpha-hemolysin proteins. As the ionic strength increased, the association rate constant of electrostatic interactions was accelerated, whereas those of both hydrophobic and aromatic interactions were retarded. Dramatic decreases in the dissociation rate constants, and thus increases in the overall reaction formation constants, were observed for all noncovalent interactions studied. The results suggest that with the increase of salt concentration, the streaming potentials for all the protein pores decrease, whereas the preferential selectivities of the pores for either cations or anions drop. Furthermore, results also show that the salt effect on the rate of association of analytes to a pore differs significantly depending on the nature of the noncovalent interactions occurring in the protein channel. In addition to providing new insights into the nature of analyte-protein pore interactions, the salt-dependence of noncovalent interactions in protein pores observed provides a useful means to greatly enhance the sensitivity of the nanopore, which may find useful application in stochastic sensing.


Assuntos
Ativação do Canal Iônico , Canais Iônicos/química , Modelos Químicos , Modelos Moleculares , Proteínas/química , Proteínas/ultraestrutura , Sítios de Ligação , Simulação por Computador , Concentração de Íons de Hidrogênio , Íons , Ligação Proteica , Conformação Proteica , Mapeamento de Interação de Proteínas/métodos , Processos Estocásticos
20.
Nanotechnology ; 19(50): 505504, 2008 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-19942772

RESUMO

In this study, we demonstrate that a pattern-recognition stochastic sensor can be constructed by employing an array of protein pores modified with a variety of non-covalent bonding sites as effective sensing elements. The collective responses of each of the individual component nanopores to a compound produce diagnostic patterns characterized by event dwell time, amplitude, and voltage dependence, which can independently or collectively serve as (an) analyte signature(s). With an increase in the dimensionality of the signal, the nanopore sensor array provides enhanced resolution for the differentiation of analytes compared to a single-pore configuration. This allows identification of a target analyte from a mixture or the potential for simultaneous detection. The pattern-recognition nanopore method is envisaged for further development as a miniaturized and automated sensing technique, which could find potential use as a laboratory or clinical tool for routine sensor applications, including environmental monitoring, drug discovery, medical diagnosis, and homeland security.

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