共查询到20条相似文献,搜索用时 15 毫秒
1.
Background
Approximately 80% of all new HIV-1 infections are acquired through sexual contact. Currently, there is no clinically approved microbicide, indicating a clear and urgent therapeutic need. We recently reported that palmitic acid (PA) is a novel and specific inhibitor of HIV-1 fusion and entry. Mechanistically, PA inhibits HIV-1 infection by binding to a novel pocket on the CD4 receptor and blocks efficient gp120-to-CD4 attachment. Here, we wanted to assess the ability of PA to inhibit HIV-1 infection in cervical tissue ex vivo model of human vagina, and determine its effect on Lactobacillus (L) species of probiotic vaginal flora.Principal Findings
Our results show that treatment with 100–200 µM PA inhibited HIV-1 infection in cervical tissue by up to 50%, and this treatment was not toxic to the tissue or to L. crispatus and jensenii species of vaginal flora. In vitro, in a cell free system that is independent of in vivo cell associated CD4 receptor; we determined inhibition constant (Ki) to be ∼2.53 µM.Significance
These results demonstrate utility of PA as a model molecule for further preclinical development of a safe and potent HIV-1 entry microbicide inhibitor. 相似文献2.
Zhukovsky MA Basmaciogullari S Pacheco B Wang L Madani N Haim H Sodroski J 《PloS one》2010,5(10):e13249
Background
The entry of human immunodeficiency virus (HIV-1) into host cells involves the interaction of the viral exterior envelope glycoprotein, gp120, and receptors on the target cell. The HIV-1 receptors are CD4 and one of two chemokine receptors, CCR5 or CXCR4.Methodology/Principal Findings
We created proteoliposomes that contain CD4, the primary HIV-1 receptor, and one of the coreceptors, CXCR4. Antibodies against CD4 and CXCR4 specifically bound the proteoliposomes. CXCL12, the natural ligand for CXCR4, and the small-molecule CXCR4 antagonist, AMD3100, bound the proteoliposomes with affinities close to those associated with the binding of these molecules to cells expressing CXCR4 and CD4. The HIV-1 gp120 exterior envelope glycoprotein bound tightly to proteoliposomes expressing only CD4 and, in the presence of soluble CD4, bound weakly to proteoliposomes expressing only CXCR4. The thermal stability of CD4 and CXCR4 inserted into liposomes was examined. Thermal denaturation of CXCR4 followed second-order kinetics, with an activation energy (Ea) of 269 kJ/mol (64.3 kcal/mol) and an inactivation temperature (Ti) of 56°C. Thermal inactivation of CD4 exhibited a reaction order of 1.3, an Ea of 278 kJ/mol (66.5 kcal/mol), and a Ti of 52.2°C. The second-order denaturation kinetics of CXCR4 is unusual among G protein-coupled receptors, and may result from dimeric interactions between CXCR4 molecules.Conclusions/Significance
Our studies with proteoliposomes containing the native HIV-1 receptors allowed an examination of the binding of biologically important ligands and revealed the higher-order denaturation kinetics of these receptors. CD4/CXCR4-proteoliposomes may be useful for the study of virus-target cell interactions and for the identification of inhibitors. 相似文献3.
Marinkovic D Tucci FC Tran JA Fleck BA Wen J Chen C 《Bioorganic & medicinal chemistry letters》2008,18(17):4817-4822
A series of piperazinebenzylalcohols were prepared and studied to compare with their ketone and amine analogs as MC4R antagonists. Several benzylalcohols such as 14a and 14g displayed low nanomolar binding affinities (Ki < 10 nM), and high selectivities over other melanocortin receptor subtypes. 相似文献
4.
Howard B. Gale Manuel D. Rodriguez Heather J. Hoffman Debra A. Benator Fred M. Gordin Ann M. Labriola Virginia L. Kan 《PloS one》2013,8(2)
Background
HIV-1 RNA and CD4 cell counts are important parameters for HIV care. The objective of this study was to assess the overall trends in HIV-1 viral load and CD4 cell counts within our clinic.Methods
Patients with at least one of each test performed by the Infectious Diseases Laboratory from 1999 through 2011 were included in this analysis. By adapting a novel statistical model, log10 HIV-1 RNA means were estimated by month, and log10-transformed HIV-1 RNA means were estimated by calendar year. Geometric means were calculated for CD4 cell counts by month and calendar year. Log10 HIV-1 RNA and CD4 cell count monthly means were also examined with polynomial regression.Results
There were 1,814 individuals with approximately 25,000 paired tests over the 13-year observation period. Based on each patient''s final value of the year, the percentage of patients with viral loads below the lower limit of quantitation rose from 29% in 1999 to 72% in 2011, while the percentage with CD4 counts <200 cells/µL fell from 31% to 11%. On average annually, the mean HIV-1 RNA decreased by 86 copies/mL and the mean CD4 counts increased by 16 cells/µL. For the monthly means, the correlations (R2) from second-order polynomial regressions were 0.944 for log10 HIV-1 RNA and 0.840 for CD4 cell counts.Conclusions
Marked improvements in HIV-1 RNA suppression and CD4 cell counts were achieved in a large inner-city population from 1999 through 2011. This success demonstrates that sustained viral control with improved immunologic status can be a realistic goal for most individuals in clinical care. 相似文献5.
Thomas A. Munro Xi-Ping Huang Carmela Inglese Maria Grazia Perrone Ashlee Van't Veer F. Ivy Carroll Cécile Béguin William A. Carlezon Jr Nicola A. Colabufo Bruce M. Cohen Bryan L. Roth 《PloS one》2013,8(8)
Background
Nor-BNI, GNTI and JDTic induce selective κ opioid antagonism that is delayed and extremely prolonged, but some other effects are of rapid onset and brief duration. The transient effects of these compounds differ, suggesting that some of them may be mediated by other targets.Results
In binding assays, the three antagonists showed no detectable affinity (K i≥10 µM) for most non-opioid receptors and transporters (26 of 43 tested). There was no non-opioid target for which all three compounds shared detectable affinity, or for which any two shared sub-micromolar affinity. All three compounds showed low nanomolar affinity for κ opioid receptors, with moderate selectivity over μ and δ (3 to 44-fold). Nor-BNI bound weakly to the α2C-adrenoceptor (K i = 630 nM). GNTI enhanced calcium mobilization by noradrenaline at the α1A-adrenoceptor (EC50 = 41 nM), but did not activate the receptor, displace radioligands, or enhance PI hydrolysis. This suggests that it is a functionally-selective allosteric enhancer. GNTI was also a weak M1 receptor antagonist (K B = 3.7 µM). JDTic bound to the noradrenaline transporter (K i = 54 nM), but only weakly inhibited transport (IC50 = 1.1 µM). JDTic also bound to the opioid-like receptor NOP (K i = 12 nM), but gave little antagonism even at 30 µM. All three compounds exhibited rapid permeation and active efflux across Caco-2 cell monolayers.Conclusions
Across 43 non-opioid CNS targets, only GNTI exhibited a potent functional effect (allosteric enhancement of α1A-adrenoceptors). This may contribute to GNTI''s severe transient effects. Plasma concentrations of nor-BNI and GNTI may be high enough to affect some peripheral non-opioid targets. Nonetheless, κ opioid antagonism persists for weeks or months after these transient effects dissipate. With an adequate pre-administration interval, our results therefore strengthen the evidence that nor-BNI, GNTI and JDTic are highly selective κ opioid antagonists. 相似文献6.
Alice V. Bakker June Daffeh Stanley Jung Lawrence A. Vincent Arthur A. Nagel Robin W. Spencer Fredric J. Vinick W. Stephen Faraci 《Bioorganic & medicinal chemistry letters》1991,1(11)
Inhibition of prolyl endopeptidase by Z-cyclohexyl prolinal and Z-indolinyl prolinal occurs with slow, tight binding inhibition and Ki values of 2 – 3 nM. In vivo enzyme inhibition is also observed with a half time for recovery of enzyme activity of 3 – 4 h.Inhibition of prolyl endopeptidase by Z-cyclohexyl prolinal and Z-indolinyl prolinal occurs with slow, tight binding inhibition and Ki values of 2 – 3 nM. In vivo enzyme inhibition is also observed with a half time for recovery of enzyme activity of 3 – 4 h. 相似文献
7.
David J. Dowling Zhen Tan Zofia M. Prokopowicz Christine D. Palmer Maura-Ann H. Matthews Gregory N. Dietsch Robert M. Hershberg Ofer Levy 《PloS one》2013,8(3)
Background
Newborns display distinct immune responses that contribute to susceptibility to infection and reduced vaccine responses. Toll-like receptor (TLR) agonists may serve as vaccine adjuvants, when given individually or in combination, but responses of neonatal leukocytes to many TLR agonists are diminished. TLR8 agonists are more effective than other TLR agonists in activating human neonatal leukocytes in vitro, but little is known about whether different TLR8 agonists may distinctly activate neonatal leukocytes. We characterized the in vitro immuno-stimulatory activities of a novel benzazepine TLR8 agonist, VTX-294, in comparison to imidazoquinolines that activate TLR8 (R-848; (TLR7/8) CL075; (TLR8/7)), with respect to activation of human newborn and adult leukocytes. Effects of VTX-294 and R-848 in combination with monophosphoryl lipid A (MPLA; TLR4) were also assessed.Methods
TLR agonist specificity was assessed using TLR-transfected HEK293 cells expressing a NF-κB reporter gene. TLR agonist-induced cytokine production was measured in human newborn cord and adult peripheral blood using ELISA and multiplex assays. Newborn and adult monocytes were differentiated into monocyte-derived dendritic cells (MoDCs) and TLR agonist-induced activation assessed by cytokine production (ELISA) and co-stimulatory molecule expression (flow cytometry).Results
VTX-294 was ∼100x more active on TLR8- than TLR7-transfected HEK cells (EC50, ∼50 nM vs. ∼5700 nM). VTX-294-induced TNF and IL-1β production were comparable in newborn cord and adult peripheral blood, while VTX-294 was ∼ 1 log more potent in inducing TNF and IL-1β production than MPLA, R848 or CL075. Combination of VTX-294 and MPLA induced greater blood TNF and IL-1β responses than combination of R-848 and MPLA. VTX-294 also potently induced expression of cytokines and co-stimulatory molecules HLA-DR and CD86 in human newborn MoDCs.Conclusions
VTX-294 is a novel ultra-potent TLR8 agonist that activates newborn and adult leukocytes and is a candidate vaccine adjuvant in both early life and adulthood. 相似文献8.
Huiyong Wei Richard Wang Zhuqing Yuan Crystal Y. Chen Dan Huang Lisa Halliday Weihua Zhong Gucheng Zeng Yun Shen Ling Shen Yunqi Wang Zheng W. Chen 《PloS one》2009,4(9)
Background
In vivo kinetics and frequencies of epitope-specific CD4 T cells in lymphoid compartments during M. tuberculosis infection and their resting memory pool after BCG vaccination remain unknown.Methodology/Findings
Macaque DR*W201 tetramer loaded with Ag85B peptide 65 was developed to directly measure epitope-specific CD4 T cells in blood and tissues form macaques after M. tuberculosis infection or BCG vaccination via direct staining and tetramer-enriched approach. The tetramer-based enrichment approach showed that P65 epitope-specific CD4 T cells emerged at mean frequencies of ∼500 and ∼4500 per 107 PBL at days 28 and 42, respectively, and at day 63 increased further to ∼22,000/107 PBL after M. tuberculosis infection. Direct tetramer staining showed that the tetramer-bound P65-specific T cells constituted about 0.2–0.3% of CD4 T cells in PBL, lymph nodes, spleens, and lungs at day 63 post-infection. 10-fold expansion of these tetramer-bound epitope-specific CD4 T cells was seen after the P65 peptide stimulation of PBL and tissue lymphocytes. The tetramer-based enrichment approach detected BCG-elicited resting memory P65-specific CD4 T cells at a mean frequency of 2,700 per 107 PBL.Significance
Our work represents the first elucidation of in vivo kinetics and frequencies for tetramer-bound epitope-specific CD4 T cells in the blood, lymphoid tissues and lungs over times after M. tuberculosis infection, and BCG immunization. 相似文献9.
Background
An integrated tiered service delivery model (ITSDM) has been proposed to provide ‘full-coverage’ of CD4 services throughout South Africa. Five tiers are described, defined by testing volumes and number of referring health-facilities. These include: (1) Tier-1/decentralized point-of-care service (POC) in a single site; Tier-2/POC-hub servicing processing <30–40 samples from 8–10 health-clinics; Tier-3/Community laboratories servicing ∼50 health-clinics, processing <150 samples/day; high-volume centralized laboratories (Tier-4 and Tier-5) processing <300 or >600 samples/day and serving >100 or >200 health-clinics, respectively. The objective of this study was to establish costs of existing and ITSDM-tiers 1, 2 and 3 in a remote, under-serviced district in South Africa.Methods
Historical health-facility workload volumes from the Pixley-ka-Seme district, and the total volumes of CD4 tests performed by the adjacent district referral CD4 laboratories, linked to locations of all referring clinics and related laboratory-to-result turn-around time (LTR-TAT) data, were extracted from the NHLS Corporate-Data-Warehouse for the period April-2012 to March-2013. Tiers were costed separately (as a cost-per-result) including equipment, staffing, reagents and test consumable costs. A one-way sensitivity analyses provided for changes in reagent price, test volumes and personnel time.Results
The lowest cost-per-result was noted for the existing laboratory-based Tiers- 4 and 5 ($6.24 and $5.37 respectively), but with related increased LTR-TAT of >24–48 hours. Full service coverage with TAT <6-hours could be achieved with placement of twenty-seven Tier-1/POC or eight Tier-2/POC-hubs, at a cost-per-result of $32.32 and $15.88 respectively. A single district Tier-3 laboratory also ensured ‘full service coverage’ and <24 hour LTR-TAT for the district at $7.42 per-test.Conclusion
Implementing a single Tier-3/community laboratory to extend and improve delivery of services in Pixley-ka-Seme, with an estimated local ∼12–24-hour LTR-TAT, is ∼$2 more than existing referred services per-test, but 2–4 fold cheaper than implementing eight Tier-2/POC-hubs or providing twenty-seven Tier-1/POCT CD4 services. 相似文献10.
11.
Navolotskaya E. V. Malkova N. V. Lepikhova T. N. Krasnova S. B. Zargarova T. A. Zav'yalov V. P. Lipkin V. M. 《Russian Journal of Bioorganic Chemistry》2001,27(5):318-322
The synthetic peptide SLTCLVKGFY, corresponding to the 364–373 amino acid sequence of the human IgG heavy chain (Immunorphin), was found to compete with [125I] -endorphin for binding by high-affinity receptors on T lymphocytes isolated from the blood of healthy donors (K
i0.6 nM). The fragments 3–10, 4–10, 5–10, and 6–10 of Immunorphin also inhibited the binding (K
i2.2, 3.4, 8.0, and 15 nM, respectively). Specificity of these receptors was studied: they turned out to be insensitive to naloxone and [Met]enkephaline and, therefore, are not opioid. The K
dvalues of the specific binding of 125I-labeled Immunorphin and its 6–10 fragment to the receptor were found to be 7.4 and 36.3 nM, respectively. 相似文献
12.
Yunda Huang Ann Duerr Nicole Frahm Lily Zhang Zoe Moodie Steve De Rosa M. Juliana McElrath Peter B. Gilbert 《PloS one》2014,9(11)
Background
Elevated risk of HIV-1 infection among recipients of an adenovirus serotype 5 (Ad5)-vectored HIV-1 vaccine was previously reported in the Step HIV-1 vaccine efficacy trial. We assessed pre-infection cellular immune responses measured at 4 weeks after the second vaccination to determine their roles in HIV-1 infection susceptibility among Step study male participants.Methods
We examined ex vivo interferon-γ (IFN-γ) secretion from peripheral blood mononuclear cells (PBMC) using an ELISpot assay in 112 HIV-infected and 962 uninfected participants. In addition, we performed flow cytometric assays to examine T-cell activation, and ex vivo IFN-γ and interleukin-2 secretion from CD4+ and CD8+ T cells. We accounted for the sub-sampling design in Cox proportional hazards models to estimate hazard ratios (HRs) of HIV-1 infection per 1-loge increase of the immune responses.Findings
We found that HIV-specific immune responses were not associated with risk of HIV-1 infection. However, each 1-loge increase of mock responses measured by the ELISpot assay (i.e., IFN-γ secretion in the absence of antigen-specific stimulation) was associated with a 62% increase of HIV-1 infection risk among vaccine recipients (HR = 1.62, 95% CI: (1.28, 2.04), p<0.001). This association remains after accounting for CD4+ or CD8+ T-cell activation. We observed a moderate correlation between ELISpot mock responses and CD4+ T-cells secreting IFN-γ (ρ = 0.33, p = 0.007). In addition, the effect of the Step vaccine on infection risk appeared to vary with ELISpot mock response levels, especially among participants who had pre-existing anti-Ad5 antibodies (interaction p = 0.04).Conclusions
The proportion of cells, likely CD4+ T-cells, producing IFN-γ without stimulation by exogenous antigen appears to carry information beyond T-cell activation and baseline characteristics that predict risk of HIV-1 infection. These results motivate additional investigation to understand the potential link between IFN-γ secretion and underlying causes of elevated HIV-1 infection risk among vaccine recipients in the Step study. 相似文献13.
Aylin Yilmaz Magnus Gisslén Serena Spudich Evelyn Lee Anura Jayewardene Francesca Aweeka Richard W. Price 《PloS one》2009,4(9)
Introduction
Raltegravir is an HIV-1 integrase inhibitor currently used in treatment-experienced HIV-1-infected patients resistant to other drug classes. In order to assess its central nervous system penetration, we measured raltegravir concentrations in cerebrospinal fluid (CSF) and plasma in subjects receiving antiretroviral treatment regimens containing this drug.Methods
Raltegravir concentrations were determined by liquid chromatography tandem mass spectrometry in 25 paired CSF and plasma samples from 16 HIV-1-infected individuals. The lower limit of quantitation was 2.0 ng/ml for CSF and 10 ng/ml for plasma.Results
Twenty-four of the 25 CSF samples had detectable raltegravir concentrations with a median raltegravir concentration of 18.4 ng/ml (range, <2.0–126.0). The median plasma raltegravir concentration was 448 ng/ml (range, 37–5180). CSF raltegravir concentrations correlated with CSF:plasma albumin ratios and CSF albumin concentrations.Conclusions
Approximately 50% of the CSF specimens exceeded the IC95 levels reported to inhibit HIV-1 strains without resistance to integrase inhibitors. In addition to contributing to control of systemic HIV-1 infection, raltegravir achieves local inhibitory concentrations in CSF in most, but not all, patients. Blood-brain and blood-CSF barriers likely restrict drug entry, while enhanced permeability of these barriers enhances drug entry. 相似文献14.
Pamela M. Murnane James P. Hughes Connie Celum Jairam R. Lingappa Nelly Mugo Carey Farquhar James Kiarie Anna Wald Jared M. Baeten for the Partners in Prevention HSV/HIV Transmission Study Team 《PloS one》2012,7(11)
Background
Current WHO guidelines recommend antiretroviral therapy (ART) initiation at CD4 counts ≤350 cells/µL. Increasing this threshold has been proposed, with a primary goal of reducing HIV-1 infectiousness. Because the quantity of HIV-1 in plasma is the primary predictor of HIV-1 transmission, consideration of plasma viral load in ART initiation guidelines is warranted.Methods
Using per-sex-act infectivity estimates and cross-sectional sexual behavior data from 2,484 HIV-1 infected persons with CD4 counts >350 enrolled in a study of African heterosexual HIV-1 serodiscordant couples, we calculated the number of transmissions expected and the number potentially averted under selected scenarios for ART initiation: i) CD4 count <500 cells/µL, ii) viral load ≥10,000 or ≥50,000 copies/mL and iii) universal treatment. For each scenario, we estimated the proportion of expected infections that could be averted, the proportion of infected persons initiating treatment, and the ratio of these proportions.Results
Initiating treatment at viral load ≥50,000 copies/mL would require treating 19.8% of infected persons with CD4 counts >350 while averting 40.5% of expected transmissions (ratio 2.0); treating at viral load ≥10,0000 copies/mL had a ratio of 1.5. In contrast, initiation at CD4 count <500 would require treating 41.8%, while averting 48.4% (ratio 1.1).Conclusion
Inclusion of viral load in ART initiation guidelines could permit targeting ART resources to HIV-1 infected persons who have a higher risk of transmitting HIV-1. Further work is needed to estimate costs and feasibility. 相似文献15.
Ajoy Basak Abdel-Majid Khatib Dayani Mohottalage Sarmistha Basak Maria Kolajova Subhendu Sekhar Bag Amit Basak 《PloS one》2009,4(11)
Background
Furin represents a crucial member of secretory mammalian subtilase, the Proprotein Convertase (PC) or Proprotein Convertase Subtilisin/Kexin (PCSK) superfamily. It has been linked to cancer, tumorgenesis, viral and bacterial pathogenesis. As a result it is considered a major target for intervention of these diseases.Methodology/Principal Findings
Herein, we report, for the first time, the synthesis and biological evaluation of a newly designed potent furin inhibitor that contains a highly reactive beta-turn inducing and radical generating “enediynyl amino acid” (Eda) moiety. “Eda” was inserted between P1 and P1′ residues of hfurin98–112 peptide, derived from the primary cleavage site of furin''s own prodomain. The resulting hexadecapeptide derivative inhibited furin in vitro with IC50 ∼40 nM when measured against the fluorogenic substrate Boc-RVRR-MCA. It also inhibited furin-mediated cleavage of a fluorogenic peptide derived from hSARS-CoV spike protein with IC50 ∼193 nM. Additionally it also blocked furin-processing of growth factors proPDGF-A, B and VEGF-C that are linked to tumor genesis and cancer. Circular dichroism study showed that this inhibitor displayed a predominantly beta-turn structure while western blots confirmed its ability to protect furin protein from self degradation.Conclusion/Significance
These findings imply its potential as a therapeutic agent for intervention of cancer and other furin-associated diseases. 相似文献16.
Herbeck JT Gottlieb GS Li X Hu Z Detels R Phair J Rinaldo C Jacobson LP Margolick JB Mullins JI 《PloS one》2008,3(2):e1525
Background
Several long-term cohort studies and in-vitro fitness assays have resulted in inconsistent reports on changes in HIV-1 virulence, including reports of decreasing, stable, and increasing virulence over the course of the AIDS pandemic. We tested the hypothesis of changing HIV-1 virulence by examining trends in prognostic clinical markers of disease progression from 1984 to 2005 among nearly 400 antiretroviral-naïve participants in the United States Multicenter AIDS Cohort Study (MACS), a longitudinal study of HIV infection in men who have sex with men (MSM).Methodology/Principal Findings
Because clinical AIDS endpoints could not be used (due to antiretroviral therapies and prophylaxis), three prognostic markers of disease progression were used as proxies for HIV-1 virulence: plasma viral RNA load and CD4+ T cell count at “set point” (between ∼9 and ∼15 months after seroconversion), and rate of CD4 cell decline within three years after seroconversion. We performed multivariate analyses of the association between these markers and seroconversion year, with covariates including MACS site, race/ethnic group, seroconversion age, and CCR5Δ32 status. No statistically significant association was found between year of seroconversion and “set point” plasma viral load (at ∼9 months after seroconversion: slope = −0.004 log10 copies/mL/year, p = 0.76; at ∼15 months: slope = −0.005 log10 copies/mL/year, p = 0.71), CD4 cell count after seroconversion (at ∼9 months: slope = −0.112 cells/µL/year, p = 0.22; at ∼15 months: slope = −0.047 cells/µL/year, p = 0.64), or rate of CD4 cell decline over the first three years after seroconversion (slope = −0.010 cells/ul/yr2, p = 0.88).Conclusions/Significance
The lack of significant trends from 1984 to 2005 in these prognostic markers of HIV disease progression suggests no major change in HIV-1 virulence over the AIDS pandemic in MSM in the US. 相似文献17.
Meriem Bahira Micah J. McCauley Ali A. Almaqwashi Per Lincoln Fredrik Westerlund Ioulia Rouzina Mark C. Williams 《Nucleic acids research》2015,43(18):8856-8867
Several multi-component DNA intercalating small molecules have been designed around ruthenium-based intercalating monomers to optimize DNA binding properties for therapeutic use. Here we probe the DNA binding ligand [μ-C4(cpdppz)2(phen)4Ru2]4+, which consists of two Ru(phen)2dppz2+ moieties joined by a flexible linker. To quantify ligand binding, double-stranded DNA is stretched with optical tweezers and exposed to ligand under constant applied force. In contrast to other bis-intercalators, we find that ligand association is described by a two-step process, which consists of fast bimolecular intercalation of the first dppz moiety followed by ∼10-fold slower intercalation of the second dppz moiety. The second step is rate-limited by the requirement for a DNA-ligand conformational change that allows the flexible linker to pass through the DNA duplex. Based on our measured force-dependent binding rates and ligand-induced DNA elongation measurements, we are able to map out the energy landscape and structural dynamics for both ligand binding steps. In addition, we find that at zero force the overall binding process involves fast association (∼10 s), slow dissociation (∼300 s), and very high affinity (Kd ∼10 nM). The methodology developed in this work will be useful for studying the mechanism of DNA binding by other multi-step intercalating ligands and proteins. 相似文献
18.
19.
To investigate the potential clinical application of aptamers to prevention of HIV infection, single-stranded DNA (ssDNA) aptamers specific for CD4 were developed using the systematic evolution of ligands by exponential enrichment approach and next generation sequencing. In contrast to RNA-based aptamers, the developed ssDNA aptamers were stable in human serum up to 12 h. Cell binding assays revealed that the aptamers specifically targeted CD4-expressing cells with high binding affinity (Kd = 1.59 nM), a concentration within the range required for therapeutic application. Importantly, the aptamers selectively bound CD4 on human cells and disrupted the interaction of viral gp120 to CD4 receptors, which is a prerequisite step of HIV-1 infection. Functional studies showed that the aptamer polymers significantly blocked binding of viral gp120 to CD4-expressing cells by up to 70% inhibition. These findings provide a new approach to prevent HIV-1 transmission using oligonucleotide aptamers. 相似文献
20.
Qian Jiang Xin Fu Lichun Tian Yuqin Chen Kai Yang Xiuqing Chen Jie Zhang Wenju Lu Jian Wang 《PloS one》2014,9(9)