作者承认比利时的瓦隆地区在 SENSOTEM 和 NANOTIC 研究项目的框架内, 以及国家科研基金 (储备-f.n.r.) 的财政支持。

1. 蛋白质样品制备
<ol><li>生产和纯化杂交蛋白 BlaP-cAb-Lys3 如我们以前的研究报告15。将蛋白质储存在50毫米磷酸盐缓冲液 pH 值7.4 以下组成: 8 克氯化钠, 0.2 克氯化钾, 1.44 克 Na2HPO4和 0.24 g 的下一2PO4溶解在800毫升蒸馏水中修复溶液的 pH 值为7。4将溶液的最终体积调整到 1 l. 过滤器对蛋白质溶液进行杀菌。</li>
	<li>准备一个母鸡卵白溶菌酶 (HEWL) 库存解决方案。溶解100毫克 (4万单位/毫克) 的商业购买 HEWL 在10毫升磷酸盐缓冲盐水 (PBS 见步骤 2.1.1)。用0.22 μ m 截止过滤器对蛋白质溶液进行消毒。</li>
</ol>2. 生物传感器检测
<ol><li>
解决方案和缓冲准备
	<ol>
<li>准备50毫米 PBS 通过溶解 8 g 氯化钠, 0.2 克氯化钾, 1.44 g Na2HPO4, 和 0.24 g 的, 在2毫升的蒸馏水4PO800 。调整到 pH 值7.4 与 1 n HCl 或 1 n 氢氧化钠, 然后调整解决方案的体积到 1 l. 过滤消毒和存储在4° c。</li>
		<li>准备一个饱和/堵塞解决方案, 溶解3克的酪蛋白水解物在100毫升的 PBS 制备如上文所述 (见步骤 2.1.1)。过滤消毒, 贮存在4° c。</li>
		<li>准备一个结合的解决方案, 溶解1克的酪蛋白水解物在100毫升的 PBS 制备如上文所述 (见步骤 2.1.1)。过滤消毒, 贮存在4° c。</li>
		<li>准备一个洗涤解决方案 (0.1% 补间-pbs), 添加100μ l 吐温 20 (100%) 在100毫升的 pbs 准备如上文所述 (见步骤 2.1.1)。贮存在4° c。</li>
		<li>准备一个电极准备解决方案 (1% 海卫 X-100-pbs), 增加1毫升的海卫 X-100 (100%) 在100毫升的 PBS 制备如上所述 (见步骤 2.1.1)。贮存在4° c。</li>
		<li>准备一个电极再生解决方案 (3.5 米氯化钾) 溶解26克的氯化钾在蒸馏水到最后一卷100毫升。过滤灭菌, 贮存在4° c。</li>
		<li>准备一个5毫米氯化钠溶液溶解0.29 克氯化钠在蒸馏水到最后的容量 1 l. 过滤器消毒并且存放在4° c。然后, 准备一个检测解决方案 (4 毫米青霉素) 溶解26.7 毫克的青霉素在20毫升5毫米氯化钠溶液。过滤消毒, 贮存在-20 ° c。</li>
	</ol>
</li>
	<li>
传感器的制备和再生 注: 聚苯胺涂层传感器芯片由 Dr. p Bogaerts、Dr. s ·尤努斯和 Prof. Glupczynski 的天主教大学 (鲁汶-拉-Neuve-楚-Godinne) 提供。对传感器的描述以及用于合成这些传感器的聚苯胺电聚合协议在以前的工作17中进行了详细介绍。简单地说, 该系统使用的是由传统印制电路板 (PCB) 技术制造的八单个芯片的可重新使用的传感器。单个芯片由三电极圆点组成。顶部是聚苯胺电合成的工作电极。中间一个是参考电极, 底部电极构成计数器电极。两个, 参考和计数器电极功能化使用固体银/氯化汞合金的顶部的碳层。<ol>
<li>执行3冲洗的电极, 浸渍的秘诀, 96-井板包含300µL/井的电极制备解决方案 (1% 海卫 X-100-PBS, 见步骤2.1.5。每洗2分钟, 在室温下进行温和搅拌。</li>
		<li>冲洗电极, 将小贴士浸入含有300µL 的96井板的井中, 并在室温下温和搅拌2分钟。</li>
		<li>在室温下, 在4° c 或 1 h 的条件下, 通过将尖端浸入96个井板 (3.5 M 氯化钾, 见步骤 2.1.6), 重新生成电极。</li>
		<li>执行3冲洗的电极, 把小费浸入96井板含300µL/井的磷酸盐缓冲盐水 (见步骤2.1.1。每洗2分钟, 在室温下进行温和搅拌。</li>
	</ol>
</li>
	<li>
在传感器上进行的结合化验
	<ol>
<li>通过将 PBS 制备的15µL 滴40µg/mL HEWL 沉积到电极表面, 将 HEWL 涂在电极上的聚苯胺表面。在室温下在4° c 或1小时孵育过夜。</li>
		<li>用磷酸盐缓冲盐水 (见步骤 2.1.1) 将传感器芯片的电极部分浸入含磷酸盐缓冲盐水300µL/井的96井板的井中, 执行三的电极洗涤。每洗2分钟, 在室温下进行温和搅拌。</li>
		<li>通过在电极表面加入50µL 滴的堵塞溶液 (见步骤 2.1.2) 使电极饱和。室温下孵育1小时。然后洗三次, 如前一步所述 (参见步骤 2.3.2)。</li>
		<li>将 BlaP-cAb-Lys3 溶液稀释到20µg/毫升的结合溶液中 (见步骤 2.1.3), 并将该稀释溶液的15µL 滴放到电极上。室温孵育10分钟。在抗原-nanobody 反应之后, 洗涤三次被描述在前步使用洗涤解答 (参见步 2.1.4)。然后用 PBS 冲洗电极 (见步骤 2.1.1)。</li>
		<li>用于检测, 将传感器芯片通过铜电路部件插入数字万用表。然后, 启动传感器的反应, 应用50µL 下降的检测解决方案 (见步骤 2.1.7) 到积极的电极和应用50µL 滴氯化钠5毫米溶液到负极 (见步骤 2.1.7)。室温孵育30分钟。用数字万用表监测电导率。 注: 万用表是由 Dr. p Bogaerts、Dr. 和 Prof. Glupczynski (鲁汶-拉-Neuve-楚 Godinne 天主教大学提供的。此电位是通过 USB 端口进行计算机控制的, 同时分析八种不同的传感器芯片。由尤努斯和同事们创建的软件17创建了一个实时图, 它表示参照和采样电极对时间的电导差的测量。</li>
	</ol>
</li>
</ol>

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E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Potentiometric+enzyme+immunoassay+using+miniaturized+anion-selective+electrodes+for+detection.">Potentiometric enzyme immunoassay using miniaturized anion-selective electrodes for detection.</a> Analyst. 134, 1601-1607 (2009).</li><li>Ding, J., Wang, X., Qin, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pulsed+galvanostatic+control+of+a+polymeric+membrane+ion-selective+electrode+for+potentiometric+immunoassays.">Pulsed galvanostatic control of a polymeric membrane ion-selective electrode for potentiometric immunoassays.</a> ACS Appl Mater Interfaces. 5, 9488-9493 (2013).</li><li>Wang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+polymeric+liquid+membrane+electrode+responsive+to+3,3',5,5'-tetramethylbenzidine+oxidation+for+sensitive+peroxidase/peroxidase+mimetic-based+potentiometric+biosensing.">A polymeric liquid membrane electrode responsive to 3,3',5,5'-tetramethylbenzidine oxidation for sensitive peroxidase/peroxidase mimetic-based potentiometric biosensing.</a> Anal Chem. 86, 4416-4422 (2014).</li><li>Grieshaber, D., MacKenzie, R., Voros, J., Reimhult, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrochemical+Biosensors+-+Sensor+Principles+and+Architectures.">Electrochemical Biosensors - Sensor Principles and Architectures.</a> Sensors (Basel). 8, 1400-1458 (2008).</li><li>Bakker, E., Pretsch, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoscale+potentiometry.">Nanoscale potentiometry.</a> Trends Analyt Chem. 27, 612-618 (2008).</li><li>Zhang, D., Liu, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biosensors+and+bioelectronics+on+smartphone+for+portable+biochemical+detection.">Biosensors and bioelectronics on smartphone for portable biochemical detection.</a> Biosens Bioelectron. 75, 273-284 (2016).</li><li>Nemiroski, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Universal+mobile+electrochemical+detector+designed+for+use+in+resource-limited+applications.">Universal mobile electrochemical detector designed for use in resource-limited applications.</a> Proc Natl Acad Sci U S A. 111, 11984-11989 (2014).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Socio-economic impact of mHealth- An assessment report for the European Union. , (2013).</li></ol>

作者没有什么可透露的。

在这项工作中, 我们提出了一种方法来化 nanobody 使用 BlaP β-酶作为载体蛋白, 我们表明, 我们可以成功地实现的结果混合蛋白的电位传感器检测。我们工作的主要创新方面与其他生物传感器的检测相比, 是抗体部分与产生电信号的酶活性的共价耦合。这种所谓的蛋白质插入技术带来的优势和局限性, 将是本节的主要重点。
混合β-酶技术的优势。
β-酶是高效...

生物传感器是一种与物理或化学信号装置相结合的分析设备, 称为传感器1。然后, 可以对记录的信号进行解释和转换, 以监测固定和自由伙伴之间的相互作用。大多数的生物传感器涉及使用抗体来检测分析如激素或不同的病原体标记物2。可以使用不同的传感器格式, 包括基于质量的、磁的、光学的或电化学的生物传感器。后者是最常用的传感器之一, 通过将绑定事件转换为电信号来发挥作用。所有基于抗体的生物传感器的性能和灵敏度主要取决于两个参数: i) 抗体的质量和 ii) 用于生成信号2的系统的属性。
抗体是由两个重链和两个光链组成的高分子质量二蛋白 (150–160 kDa)。光与重链之间的相互作用主要通过疏水相互作用以及一个守恒的二硫化键稳定。每个链包括一个变量域, 它通过三变区域 (CDR1-2-3) 来与抗原相互作用。尽管在该领域取得了许多进展, 但具有低成本表达系统 (例如、大肠杆菌) 的全长抗体的大规模表达往往导致不稳定和聚合蛋白的产生。这就是为什么各种各样的抗体片段被设计了例如单链可变片段3 (ScFvs ≈ 25 kDa)。它们由一个重和一个轻链的可变域组成, 由一个合成氨基酸序列共价键连接。然而, 这些碎片往往表现出很差的稳定性, 并有聚合的倾向, 因为它们将其疏水区域的很大一部分暴露给溶剂4。在这种情况下, 单链骆驼抗体片段, 称为 nanobodies 或 VHHs, 似乎是很好的替代 ScFvs。这些域对应于骆驼单链抗体的可变域。与常规抗体相比, 骆驼抗体缺乏光链, 只包含两个重链5。因此, nanobodies 是最小的单体抗体片段 (12 kDa) 能够绑定到一个抗原的亲和力类似于常规抗体6。此外, 与其他全长抗体或抗体片段相比, 它们具有更好的稳定性和溶解度。最后, 他们的小尺寸和他们的扩展 CDR3 循环允许他们辨认隐晦的表位并且束缚到酵素活跃站点7,8。目前, 这些领域得到了相当的重视, 并已与生物传感器技术相结合。例如, 黄等人。开发了一种基于 nanobody 的生物传感器, 用于检测和量化人类前列腺特异抗原 (PSA)9。
如上所述, 生物传感器检测的一个重要参数是用于产生电信号的系统的效率。因此, 基于酶的电化学生物传感器越来越受到人们的关注, 并被广泛应用于医疗保健、食品安全和环境监测等各种领域。这些生物传感器依赖于一种酶对基质的催化水解来产生电信号。在这种情况下, β-酶被证明是更具体, 更敏感和更容易实施实验比其他许多酶, 如碱性磷酸酶或辣根过氧化物酶10。β-酶是酶, 负责对β内酰胺抗生素的细菌耐药性, 通过水解它们。它们单体, 非常稳定, 高效, 体积小。此外, 域/肽插入β-酶产生双功能嵌合蛋白, 被证明是研究蛋白质-配体相互作用的有效工具。事实上, 最近的研究表明, 在 TEM1 β-酶中插入抗体可变片段的结果是嵌合蛋白, 仍然能够与其靶抗原的高度亲和性结合。有趣的是, 抗原结合被证明能诱发 TEM1 催化活性的构调节11,12。此外, 我们在几项研究中表明, 蛋白质域插入到一个允许循环的芽孢杆菌地衣BlaP β-酶产生功能嵌合蛋白, 非常适合监测蛋白配体的相互作用13 ,14。我们最近在 BlaP15的这个允许插入站点中插入了一个名为 cAb-Lys3 的 nanobody。这 nanobody 被证明绑定到母鸡-蛋清溶菌酶 (HEWL) 和抑制其酶活性16。我们表明, 生成的杂交蛋白, 命名为 BlaP-cAb-Lys3, 保留了高特异性/亲和力对 HEWL, 而β-酶活性保持不变。然后, 我们成功地将混合β-酶技术与电化学生物传感器相结合, 结果表明, 产生的电信号量与固定在电极上的 BlaP-cAb-Lys3 和 HEWL 的相互作用有关。事实上, β-内酰胺抗生素的水解 BlaP 诱导质子释放, 可以转化为定量的电信号。这种组合的混合β-酶技术与电化学生物传感器是快速, 灵敏, 定量, 并允许实时测量生成的信号。本文介绍了这种方法。

<table><tbody><tr><td>&lt;strong&gt;Reagents&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>KH&lt;sub&gt;2&lt;/sub&gt;PO&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma-Aldricht</td><td>V000225&amp;nbsp;</td><td></td></tr><tr><td>K&lt;sub&gt;2&lt;/sub&gt;HPO&lt;sub&gt;4&lt;/sub&gt;</td><td>Sigma-Aldricht</td><td>1551128</td><td></td></tr><tr><td>NaCl</td><td>Sigma-Aldricht</td><td>S7653</td><td></td></tr><tr><td>Tris&amp;ndash;HCl</td><td>Roche</td><td>10812846001</td><td></td></tr><tr><td>EDTA&amp;nbsp;</td><td>Sigma-Aldricht</td><td>E9884</td><td></td></tr><tr><td>KCl</td><td>Sigma-Aldricht</td><td>P9541</td><td></td></tr><tr><td>Na&lt;sub&gt;2&lt;/sub&gt;HPO&lt;sub&gt;4&lt;/sub&gt;&amp;nbsp;</td><td>Sigma-Aldricht</td><td>NIST2186II</td><td></td></tr><tr><td>2-mercaptoethanol</td><td>Sigma-Aldricht</td><td>M6250</td><td></td></tr><tr><td>alanine</td><td>Sigma-Aldricht</td><td>A7627</td><td></td></tr><tr><td>HClO&lt;sub&gt;4&lt;/sub&gt;</td><td>Fluka</td><td>34288</td><td>1M HClO4 solution, distributor : Sigma-Aldricht</td></tr><tr><td>casein hydrolysate</td><td>Sigma-Aldricht</td><td>22090</td><td></td></tr><tr><td>benzylpenicillin sodium</td><td>Sigma-Aldricht</td><td>B0900000</td><td></td></tr><tr><td>hen egg white lysozyme</td><td>Roche</td><td>10837059001</td><td></td></tr><tr><td>heptane</td><td>Sigma-Aldricht</td><td>246654</td><td></td></tr><tr><td>methanol</td><td>Sigma-Aldricht</td><td>322415</td><td></td></tr><tr><td>ammonium hydroxide solution</td><td>Sigma-Aldricht</td><td>380539</td><td>28% NH3&amp;nbsp;in H2O, purified by double-distillation (concentrated?)</td></tr><tr><td>&lt;strong&gt;Laboratory consumables&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>6-well plate&amp;nbsp;</td><td>Greiner Bio-One</td><td>657165</td><td>CELLSTAR 6-Well Plate</td></tr><tr><td>&lt;strong&gt;Equipment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>pH meter</td><td>WTW</td><td>1AA110</td><td>Lab pH meter inoLab pH 7110</td></tr><tr><td>vacuum and filtration system</td><td>Nalgene</td><td>NALG300-4100</td><td>Filter holders with receiver, distributor : VWR</td></tr><tr><td>potentiometric sensor chips</td><td></td><td></td><td>manufactured by Yunus and colleagues (ref 16)</td></tr><tr><td>PGSTAT30 Autolab</td><td>Metrohm Autolab</td><td></td><td>discontinued, succesor Autolab PGSTAT302N</td></tr><tr><td>digital multimeter, METRAHit 22M</td><td>Gossen Metrawatt</td><td></td><td>discontinued, successor Metrahit Base</td></tr></tbody></table>

the use of a &#946;-lactamase-based conductimetric biosensor assay to detect biomolecular interactions

生物传感器在病原检测、分子诊断、环境监测、食品安全控制等各个领域的应用越来越重要。在这方面, 我们使用β-酶作为有效的报告酶在几个蛋白质-蛋白质相互作用研究。此外, 他们接受多肽或结构蛋白/域插入的能力强烈鼓励使用这些酶产生嵌合蛋白。在最近的一项研究中, 我们在芽孢杆菌地衣BlaP β-酶中插入了一个单域抗体片段。这些小的域, 也称为 nanobodies, 被定义为骆驼单链抗体的抗原结合域。就像常见的双链抗体一样, 它们具有很高的亲和力和特异的靶向。所产生的嵌合蛋白在保持β-酶活性的同时, 对其靶向性具有较高的亲和力。这表明, nanobody 和β-酶基保持功能。在目前的工作中, 我们报告了一个详细的协议, 结合我们的混合β-酶系统的生物传感器技术。由于酶的催化活性释放出的质子的电导测量, 可以检测到 nanobody 对其目标的特定约束力。

嵌合蛋白 BlaP-cAb-Lys3 的设计与工程
图1表示将 cAb-Lys3 插入到 BalP 类的一个允许循环中, 从地衣芽孢杆菌中的β-酶。在残余 Asp198 和 Lys199 之间进行插入。在 cAb-Lys3 的两侧引入了凝血酶劈裂部位。用本构表达质粒对 BlaP-cAb-Lys3 嵌合蛋白进行转化的细胞能够在氨苄青霉素的小浓度下生长。这一结果表明, 杂交β-酶是可溶性的, 正?...

Watch this Scientific Journal Video about The Use of a Î²-lactamase-based Conductimetric Biosensor Assay to Detect Biomolecular Interactions at JoVE.com

The Use of a &#946;-lactamase-based Conductimetric Biosensor Assay to Detect Biomolecular Interactions

在这项工作中, 我们报告了一个新的方法来研究蛋白质-蛋白质相互作用的电导生物传感器的基础上的混合β-酶技术。这种方法依赖于质子在β-内酰胺水解时的释放。

基于β-酶的电导生物传感器检测技术在分子间相互作用中的应用

Biosensors are becoming increasingly important and implemented in various fields such as pathogen detection, molecular diagnosis, environmental ...

the-use-lactamase-based-conductimetric-biosensor-assay-to-detect

Universidad de Cartagena UDEC

Research

JoVE Journal

Bioengineering

8.9K 次观看.  University of Liège. 在这项工作中, 我们报告了一个新的方法来研究蛋白质-蛋白质相互作用的电导生物传感器的基础上的混合β-酶技术。这种方法依赖于质子在β-内酰胺水解时的释放。

视频: The Use of a β-lactamase-based Conductimetric Biosensor Assay to Detect Biomolecular Interactions

Bio-layer Interferometry for Measuring Kinetics of Protein-protein Interactions and Allosteric Ligand Effects

We describe the use of Bio-layer Interferometry to study inhibitory interactions of subunit &#949;&#160;with the catalytic complex of Escherichia coli&#160;ATP synthase. Bacterial F-type ATP synthase is the target of a new, FDA-approved antibiotic to combat drug-resistant tuberculosis. Understanding bacteria-specific auto-inhibition of ATP synthase by the C-terminal domain of subunit &#949;&#160;could provide a new means to target the enzyme for discovery of antibacterial drugs. The C-terminal domain of &#949;&#160;undergoes a dramatic conformational change when the enzyme transitions between the active and inactive states, and catalytic-site ligands can influence which of &#949;&#39;s conformations is predominant. The assay measures kinetics of &#949;&#39;s binding/dissociation with the catalytic complex, and indirectly measures the shift of enzyme-bound &#949;&#160;to and from the apparently nondissociable inhibitory conformation. The Bio-layer Interferometry signal is not overly sensitive to solution composition, so it can also be used to monitor allosteric effects of catalytic-site ligands on &#949;&#39;s conformational changes.

The protocols here describe kinetic assays of protein-protein interactions with Bio-layer Interferometry. F-type ATP synthase, which is involved in cellular energy metabolism, can be inhibited by its &#949; subunit in bacteria. We have adapted Bio-layer Interferometry to study interactions of the catalytic complex with &#949;&#8217;s inhibitory C-terminal domain.

生物层干涉测量的蛋白质 - 蛋白质相互作用和变构配体反应动力学的影响

We describe the use of Bio-layer Interferometry to study inhibitory interactions of subunit &#949;&#160;with the catalytic complex of Escherichia ...

科研

化学

Determination of High-affinity Antibody-antigen Binding Kinetics Using Four Biosensor Platforms

Label-free optical biosensors are powerful tools in drug discovery for the characterization of biomolecular interactions. In this study, we describe the use of four routinely used biosensor platforms in our laboratory to evaluate the binding affinity and kinetics of ten high-affinity monoclonal antibodies (mAbs) against human proprotein convertase subtilisin kexin type 9 (PCSK9). While both Biacore T100 and ProteOn XPR36 are derived from the well-established Surface Plasmon Resonance (SPR) technology, the former has four flow cells connected by serial flow configuration, whereas the latter presents 36 reaction spots in parallel through an improvised 6 x 6 crisscross microfluidic channel configuration. The IBIS MX96 also operates based on the SPR sensor technology, with an additional imaging feature that provides detection in spatial orientation. This detection technique coupled with the Continuous Flow Microspotter (CFM) expands the throughput significantly by enabling multiplex array printing and detection of 96 reaction sports simultaneously. In contrast, the Octet RED384 is based on the BioLayer Interferometry (BLI) optical principle, with fiber-optic probes acting as the biosensor to detect interference pattern changes upon binding interactions at the tip surface. Unlike the SPR-based platforms, the BLI system does not rely on continuous flow fluidics; instead, the sensor tips collect readings while they are immersed in analyte solutions of a 384-well microplate during orbital agitation.
Each of these biosensor platforms has its own advantages and disadvantages. To provide a direct comparison of these instruments&#39; ability to provide quality kinetic data, the described protocols illustrate experiments that use the same assay format and the same high-quality reagents to characterize antibody-antigen kinetics that fit the simple 1:1 molecular interaction model.

We describe here protocols for the measurement of antibody-antigen binding affinity and kinetics using four commonly used biosensor platforms.

高亲和力抗体 - 抗原的结合动力学的测定，使用四个生物传感器平台

Label-free optical biosensors are powerful tools in drug discovery for the characterization of biomolecular interactions. In this study, we describe the ...

生物化学

Bacterial Detection &amp; Identification Using Electrochemical Sensors

Electrochemical sensors are widely used for rapid and accurate measurement of blood glucose and can be adapted for detection of a wide variety of analytes. Electrochemical sensors operate by transducing a biological recognition event into a useful electrical signal. Signal transduction occurs by coupling the activity of a redox enzyme to an amperometric electrode. Sensor specificity is either an inherent characteristic of the enzyme, glucose oxidase in the case of a glucose sensor, or a product of linkage between the enzyme and an antibody or probe.
Here, we describe an electrochemical sensor assay method to directly detect and identify bacteria. In every case, the probes described here are DNA oligonucleotides. This method is based on sandwich hybridization of capture and detector probes with target ribosomal RNA (rRNA). The capture probe is anchored to the sensor surface, while the detector probe is linked to horseradish peroxidase (HRP). When a substrate such as 3,3',5,5'-tetramethylbenzidine (TMB) is added to an electrode with capture-target-detector complexes bound to its surface, the substrate is oxidized by HRP and reduced by the working electrode. This redox cycle results in shuttling of electrons by the substrate from the electrode to HRP, producing current flow in the electrode.

Bacterial Detection & Identification Using Electrochemical Sensors

We describe an electrochemical sensor assay method for rapid bacterial detection and identification. The assay involves a sensor array functionalized with DNA oligonucleotide capture probes for ribosomal RNA (rRNA) species-specific sequences. Sandwich hybridization of target rRNA with the capture probe and a horseradish peroxidase-linked DNA oligonucleotide detector probe produces a measurable amperometric current.

使用电化学传感器的细菌检测和鉴定

Electrochemical  sensors are widely used for rapid and accurate measurement of blood glucose and  can be adapted for detection of a wide variety of ...

生物工程

Analyzing Dynamic Protein Complexes Assembled On and Released From Biolayer Interferometry Biosensor Using Mass Spectrometry and Electron Microscopy

In vivo, proteins are often part of large macromolecular complexes where binding specificity and dynamics ultimately dictate functional outputs. In this work, the pre-endosomal anthrax toxin is assembled and transitioned into the endosomal complex. First, the N-terminal domain of a cysteine mutant lethal factor (LFN) is attached to a biolayer interferometry (BLI) biosensor through disulfide coupling in an optimal orientation, allowing protective antigen (PA) prepore to bind (Kd 1 nM). The optimally oriented LFN-PAprepore complex then binds to soluble capillary morphogenic gene-2 (CMG2) cell surface receptor (Kd 170 pM), resulting in a representative anthrax pre-endosomal complex, stable at pH 7.5. This assembled complex is then subjected to acidification (pH 5.0) representative of the late endosome environment to transition the PAprepore into the membrane inserted pore state. This PApore state results in a weakened binding between the CMG2 receptor and the LFN-PApore and a substantial dissociation of CMG2 from the transition pore. The thio-attachment of LFN to the biosensor surface is easily reversed by dithiothreitol. Reduction on the BLI biosensor surface releases the LFN-PAprepore-CMG2 ternary complex or the acid transitioned LFN-PApore complexes into microliter volumes. Released complexes are then visualized and identified using electron microscopy and mass spectrometry. These experiments demonstrate how to monitor the kinetic assembly/disassembly of specific protein complexes using label-free BLI methodologies and evaluate the structure and identity of these BLI assembled complexes by electron microscopy and mass spectrometry, respectively, using easy-to-replicate sequential procedures.

Here we present a protocol to monitor the assembly and disassembly of the anthrax toxin using biolayer interferometry (BLI). Following assembly/disassembly on the biosensor surface, the large protein complexes are released from the surface for visualization and identification of components of the complexes using electron microscopy and mass spectrometry, respectively.

用质谱和电镜分析 Biolayer 干涉传感器上的动态蛋白复合物的组装和释放

In vivo, proteins are often part of large macromolecular complexes where binding specificity and dynamics ultimately dictate functional outputs. In this ...

Nanomechanics of Drug-target Interactions and Antibacterial Resistance Detection

The cantilever sensor, which acts as a transducer of reactions between model bacterial cell wall matrix immobilized on its surface and antibiotic drugs in solution, has shown considerable potential in biochemical sensing applications with unprecedented sensitivity and specificity1-5. The drug-target interactions generate surface stress, causing the cantilever to bend, and the signal can be analyzed optically when it is illuminated by a laser. The change in surface stress measured with nano-scale precision allows disruptions of the biomechanics of model bacterial cell wall targets to be tracked in real time. Despite offering considerable advantages, multiple cantilever sensor arrays have never been applied in quantifying drug-target binding interactions.
Here, we report on the use of silicon multiple cantilever arrays coated with alkanethiol self-assembled monolayers mimicking bacterial cell wall matrix to quantitatively study antibiotic binding interactions. To understand the impact of vancomycin on the mechanics of bacterial cell wall structures1,6,7.&#160;We developed a new model1 which proposes that cantilever bending can be described by two independent factors; i) namely a chemical factor, which is given by a classical Langmuir adsorption isotherm, from which we calculate the thermodynamic equilibrium dissociation constant (Kd) and ii) a geometrical factor, essentially a measure of how bacterial peptide receptors are distributed on the cantilever surface. The surface distribution of peptide receptors (p) is used to investigate the dependence of geometry and ligand loading. It is shown that a threshold value of p ~10% is critical to sensing applications. Below which there is no detectable bending signal while above this value, the bending signal increases almost linearly,&#160;revealing that stress is a product of a local chemical binding factor and a geometrical factor combined by the mechanical connectivity of reacted regions and provides a new paradigm for design of powerful agents to combat superbug infections.

Acquired resistance to antibiotics is a major public healthcare problem and is presently ranked by the WHO as one of the greatest threats to human life. Here we describe the use of cantilever technology to quantify antibacterial resistance, critical to the discovery of novel and powerful agents against multidrug resistant bacteria.

纳米力学的药物靶标相互作用及耐药性检测

The cantilever sensor, which acts as a transducer of reactions between model bacterial cell wall matrix immobilized on its surface and antibiotic drugs in ...

免疫与感染

Exploring Biomolecular Interaction Between the Molecular Chaperone Hsp90 and Its Client Protein Kinase Cdc37 using Field-Effect Biosensing Technology

Biomolecular interactions play versatile roles in numerous cellular processes&#160;by regulating and coordinating functionally relevant biological events. Biomolecules such as proteins, carbohydrates, vitamins, fatty acids, nucleic acids, and enzymes are fundamental building blocks of living beings; they assemble into complex networks in biosystems to synchronize a myriad of life events. Proteins typically utilize complex interactome networks to carry out their functions; hence it is mandatory to evaluate such interactions to unravel their importance in cells at both cellular and organism levels. Toward this goal, we introduce a rapidly emerging technology, field-effect biosensing (FEB), to determine specific biomolecular interactions. FEB is a benchtop, label-free, and reliable biomolecular detection technique to determine specific interactions and uses high-quality electronic-based biosensors. The FEB technology can monitor interactions in the nanomolar range due to the biocompatible nanomaterials used on its biosensor surface. As a proof of concept, the protein-protein interaction (PPI) between heat shock protein 90 (Hsp90) and cell division cycle 37 (Cdc37) was elucidated. Hsp90 is an ATP-dependent molecular chaperone that plays an essential role in the folding, stability, maturation, and quality control of many proteins, thereby regulating multiple vital cellular functions. Cdc37 is regarded as a protein kinase-specific molecular chaperone, as it specifically recognizes and recruits protein kinases to Hsp90 to regulate their downstream signal transduction pathways. As such, Cdc37 is considered a co-chaperone of Hsp90. The chaperone-kinase pathway (Hsp90/Cdc37 complex) is hyper-activated in multiple malignancies promoting cellular growth; therefore, it is a potential target for cancer therapy. The present study demonstrates the efficiency of FEB technology using the Hsp90/Cdc37 model system. FEB detected a strong PPI between the two proteins (KD values of 0.014 &#181;M, 0.053 &#181;M, and 0.072 &#181;M in three independent experiments). In summary, FEB is a label-free and cost-effective PPI detection platform, which offers fast and accurate measurements.

Field-effect biosensing (FEB) is a label-free technique for detecting biomolecular interactions. It measures the electric current through the graphene biosensor to which the binding targets are immobilized. The FEB technology was used to evaluate biomolecular interactions between Hsp90 and Cdc37 and a strong interaction between the two proteins was detected.

使用场效应生物传感技术探索分子伴侣Hsp90与其客户蛋白激酶Cdc37之间的生物分子相互作用

Biomolecular interactions play versatile roles in numerous cellular processes&#160;by regulating and coordinating functionally relevant biological events. ...

Ultrasensitive Detection of Biomarkers by Using a Molecular Imprinting Based Capacitive Biosensor

The ability to detect and quantitate biomolecules in complex solutions has always been highly sought-after within natural science; being used for the detection of biomarkers, contaminants, and other molecules of interest. A commonly used technique for this purpose is the Enzyme-linked Immunosorbent Assay (ELISA), where often one antibody is directed towards a specific target molecule, and a second labeled antibody is used for the detection of the primary antibody, allowing for the absolute quantification of the biomolecule under study. However, the usage of antibodies as recognition elements limits the robustness of the method; as does the need of using labeled molecules. To overcome these limitations, molecular imprinting has been implemented, creating artificial recognition sites complementary to the template molecule, and obsoleting the necessity of using antibodies for initial binding. Further, for even higher sensitivity, the secondary labeled antibody can be replaced by biosensors relying on the capacitance for the quantification of the target molecule. In this protocol, we describe a method to rapidly and label-free detect and quantitate low-abundant biomolecules (proteins and viruses) in complex samples, with a sensitivity that is significantly better than commonly used detection systems such as the ELISA. This is all mediated by molecular imprinting in combination with a capacitance biosensor.

Here, we present a protocol for the detection and quantification of low abundant molecules in complex solutions using molecular imprinting in combination with a capacitance biosensor.

基于分子印迹的电容生物传感器超灵敏检测生物标志物

The ability to detect and quantitate biomolecules in complex solutions has always been highly sought-after within natural science; being used for the ...

<meta charset="utf8"></head><body>使用无标记方法定量分析 RPA-ssDNA 结合动力学

Analyzing DNA-Protein Interactions with Streptavidin-Based Biolayer Interferometry

Protein-DNA interactions underpin essential cellular processes. Understanding these interactions is critical for elucidating the molecular mechanisms of various pathways. Key factors such as the structure, sequence, and length of a DNA molecule can significantly influence protein binding. Bio-layer interferometry (BLI) is a label-free technique that measures binding kinetics between molecules, offering a straightforward and precise approach to quantitatively study protein-DNA interactions. A major advantage of BLI over traditional gel-based methods is its ability to provide real-time data on binding kinetics, enabling accurate measurement of the equilibrium dissociation constant (KD) for dynamic protein-DNA interactions. This article presents a basic protocol for determining the KD value of the interaction between a DNA replication protein, replication protein A (RPA), and a single-stranded DNA (ssDNA) substrate. RPA binds ssDNA with high affinity but must also be easily displaced to facilitate subsequent protein interactions within biological pathways. In the described BLI assay, biotinylated ssDNA is immobilized on a streptavidin-coated biosensor. The binding kinetics (association and dissociation) of RPA to the biosensor-bound DNA are then measured. The resulting data are analyzed to derive precise values for the association rate constant (ka), dissociation rate constant (kd), and equilibrium binding constant (KD) using system software.

<meta charset="utf8"></head><body>使用基于链霉亲和素的生物膜干涉测量法分析 DNA-蛋白质相互作用

This article describes a protocol for studying DNA-protein interactions using a streptavidin-based biolayer interferometry (BLI) system. It outlines the essential steps and considerations for utilizing either basic or advanced binding kinetics to determine the equilibrium binding affinity (KD) of the interaction.

使用基于链霉亲和素的生物膜干涉测量法分析 DNA-蛋白质相互作用

Protein-DNA interactions underpin essential cellular processes. Understanding these interactions is critical for elucidating the molecular mechanisms of ...

基于β-酶的电导生物传感器检测技术在分子间相互作用中的应用

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此视频中的章节

生物层干涉测量的蛋白质 - 蛋白质相互作用和变构配体反应动力学的影响

高亲和力抗体 - 抗原的结合动力学的测定，使用四个生物传感器平台

使用电化学传感器的细菌检测和鉴定

用质谱和电镜分析 Biolayer 干涉传感器上的动态蛋白复合物的组装和释放

纳米力学的药物靶标相互作用及耐药性检测

使用场效应生物传感技术探索分子伴侣Hsp90与其客户蛋白激酶Cdc37之间的生物分子相互作用

基于分子印迹的电容生物传感器超灵敏检测生物标志物

使用基于链霉亲和素的生物膜干涉测量法分析 DNA-蛋白质相互作用

使用基于链霉亲和素的生物膜干涉测量法分析 DNA-蛋白质相互作用

使用基于链霉亲和素的生物膜干涉测量法分析 DNA-蛋白质相互作用