我们要感谢我们的资金来源，包括来自洁具基金会（以JPV）一份厚礼，HealthGrant T32-CA079448（到PJS）和鲍尔州立大学的启动资金（以PJS）全国学院。该资助者在研究设计，数据收集和分析，决定发表或准备手稿没有作用。

<ol>
	<li>Qin, Y., Hurley, L. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structures,+folding+patterns,+and+functions+of+intramolecular+DNA+G-quadruplexes+found+in+eukaryotic+promoter+regions.">Structures, folding patterns, and functions of intramolecular DNA G-quadruplexes found in eukaryotic promoter regions.</a> Biochimie. 90 (8), 1149-1171 (2008).</li><li>Stegle, O., Payet, L., Mergny, J. L., MacKay, D. J., Leon, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Predicting+and+understanding+the+stability+of+G-quadruplexes.">Predicting and understanding the stability of G-quadruplexes.</a> Bioinformatics. 25 (12), i374-i382 (2009).</li><li>Todd, A. K., Johnston, M., Neidle, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+prevalent+putative+quadruplex+sequence+motifs+in+human+DNA.">Highly prevalent putative quadruplex sequence motifs in human DNA.</a> Nucleic Acids Res. 33 (9), 2901-2907 (2005).</li><li>Huppert, J. L., Balasubramanian, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prevalence+of+quadruplexes+in+the+human+genome.">Prevalence of quadruplexes in the human genome.</a> Nucleic Acids Res. 33 (9), 2908-2916 (2005).</li><li>Bedrat, A., Lacroix, L., Mergny, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Re-evaluation+of+G-quadruplex+propensity+with+G4Hunter.">Re-evaluation of G-quadruplex propensity with G4Hunter.</a> Nucleic Acids Res. 44 (4), 1746-1759 (2016).</li><li>Mendoza, O., Bourdoncle, A., Boule, J. B., Brosh, R. M., Mergny, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=G-quadruplexes+and+helicases.">G-quadruplexes and helicases.</a> Nucleic Acids Res. 44 (5), 1989-2006 (2016).</li><li>Huppert, J. L., Balasubramanian, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=G-quadruplexes+in+promoters+throughout+the+human+genome.">G-quadruplexes in promoters throughout the human genome.</a> Nucleic Acids Res. 35 (2), 406-413 (2007).</li><li>Eddy, J., Maizels, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+function+correlates+with+potential+for+G4+DNA+formation+in+the+human+genome.">Gene function correlates with potential for G4 DNA formation in the human genome.</a> Nucleic Acids Res. 34 (14), 3887-3896 (2006).</li><li>Eddy, J., 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=G4+motifs+correlate+with+promoter-proximal+transcriptional+pausing+in+human+genes.">G4 motifs correlate with promoter-proximal transcriptional pausing in human genes.</a> Nucleic Acids Res. 39 (12), 4975-4983 (2011).</li><li>Vaughn, J. P., 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=The+DEXH+protein+product+of+the+DHX36+gene+is+the+major+source+of+tetramolecular+quadruplex+G4-DNA+resolving+activity+in+HeLa+cell+lysates.">The DEXH protein product of the DHX36 gene is the major source of tetramolecular quadruplex G4-DNA resolving activity in HeLa cell lysates.</a> J Biol Chem. 280 (46), 38117-38120 (2005).</li><li>Booy, E. P., 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=The+RNA+helicase+RHAU+(DHX36)+unwinds+a+G4-quadruplex+in+human+telomerase+RNA+and+promotes+the+formation+of+the+P1+helix+template+boundary.">The RNA helicase RHAU (DHX36) unwinds a G4-quadruplex in human telomerase RNA and promotes the formation of the P1 helix template boundary.</a> Nucleic Acids Res. 40 (9), 4110-4124 (2012).</li><li>Creacy, S. D., 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=G4+resolvase+1+binds+both+DNA+and+RNA+tetramolecular+quadruplex+with+high+affinity+and+is+the+major+source+of+tetramolecular+quadruplex+G4-DNA+and+G4-RNA+resolving+activity+in+HeLa+cell+lysates.">G4 resolvase 1 binds both DNA and RNA tetramolecular quadruplex with high affinity and is the major source of tetramolecular quadruplex G4-DNA and G4-RNA resolving activity in HeLa cell lysates.</a> J Biol Chem. 283 (50), 34626-34634 (2008).</li><li>Giri, B., 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=G4+resolvase+1+tightly+binds+and+unwinds+unimolecular+G4-DNA.">G4 resolvase 1 tightly binds and unwinds unimolecular G4-DNA.</a> Nucleic Acids Res. 39 (16), 7161-7178 (2011).</li><li>Lattmann, S., Stadler, M. B., Vaughn, J. P., Akman, S. A., Nagamine, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+DEAH-box+RNA+helicase+RHAU+binds+an+intramolecular+RNA+G-quadruplex+in+TERC+and+associates+with+telomerase+holoenzyme.">The DEAH-box RNA helicase RHAU binds an intramolecular RNA G-quadruplex in TERC and associates with telomerase holoenzyme.</a> Nucleic Acids Res. 39 (21), 9390-9404 (2011).</li><li>Sexton, A. N., Collins, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+5'+guanosine+tracts+of+human+telomerase+RNA+are+recognized+by+the+G-quadruplex+binding+domain+of+the+RNA+helicase+DHX36+and+function+to+increase+RNA+accumulation.">The 5' guanosine tracts of human telomerase RNA are recognized by the G-quadruplex binding domain of the RNA helicase DHX36 and function to increase RNA accumulation.</a> Mol Cell Biol. 31 (4), 736-743 (2011).</li><li>Smaldino, P. J., 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=Mutational+Dissection+of+Telomeric+DNA+Binding+Requirements+of+G4+Resolvase+1+Shows+that+G4-Structure+and+Certain+3'-Tail+Sequences+Are+Sufficient+for+Tight+and+Complete+Binding.">Mutational Dissection of Telomeric DNA Binding Requirements of G4 Resolvase 1 Shows that G4-Structure and Certain 3'-Tail Sequences Are Sufficient for Tight and Complete Binding.</a> PLoS One. 10 (7), e0132668 (2015).</li><li>Booy, E. P., 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=The+RNA+helicase+RHAU+(DHX36)+suppresses+expression+of+the+transcription+factor+PITX1.">The RNA helicase RHAU (DHX36) suppresses expression of the transcription factor PITX1.</a> Nucleic Acids Res. 42 (5), 3346-3361 (2014).</li><li>Huang, W., 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=Yin+Yang+1+contains+G-quadruplex+structures+in+its+promoter+and+5'-UTR+and+its+expression+is+modulated+by+G4+resolvase+1.">Yin Yang 1 contains G-quadruplex structures in its promoter and 5'-UTR and its expression is modulated by G4 resolvase 1.</a> Nucleic Acids Res. 40 (3), 1033-1049 (2012).</li><li>Tran, H., Schilling, M., Wirbelauer, C., Hess, D., Nagamine, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Facilitation+of+mRNA+deadenylation+and+decay+by+the+exosome-bound,+DExH+protein+RHAU.">Facilitation of mRNA deadenylation and decay by the exosome-bound, DExH protein RHAU.</a> Mol Cell. 13 (1), 101-111 (2004).</li><li>Yoo, J. S., 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=DHX36+enhances+RIG-I+signaling+by+facilitating+PKR-mediated+antiviral+stress+granule+formation.">DHX36 enhances RIG-I signaling by facilitating PKR-mediated antiviral stress granule formation.</a> PLoS Pathog. 10 (3), e1004012 (2014).</li><li>Lai, J. C., 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=The+DEAH-box+helicase+RHAU+is+an+essential+gene+and+critical+for+mouse+hematopoiesis.">The DEAH-box helicase RHAU is an essential gene and critical for mouse hematopoiesis.</a> Blood. 119 (18), 4291-4300 (2012).</li><li>Zhang, Z., 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=DDX1,+DDX21,+and+DHX36+helicases+form+a+complex+with+the+adaptor+molecule+TRIF+to+sense+dsRNA+in+dendritic+cells.">DDX1, DDX21, and DHX36 helicases form a complex with the adaptor molecule TRIF to sense dsRNA in dendritic cells.</a> Immunity. 34 (6), 866-878 (2011).</li><li>Kim, T., 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=Aspartate-glutamate-alanine-histidine+box+motif+(DEAH)/RNA+helicase+A+helicases+sense+microbial+DNA+in+human+plasmacytoid+dendritic+cells.">Aspartate-glutamate-alanine-histidine box motif (DEAH)/RNA helicase A helicases sense microbial DNA in human plasmacytoid dendritic cells.</a> Proc Natl Acad Sci U S A. 107 (34), 15181-15186 (2010).</li><li>Booy, E. P., McRae, E. K., McKenna, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biochemical+characterization+of+G4+quadruplex+telomerase+RNA+unwinding+by+the+RNA+helicase+RHAU.">Biochemical characterization of G4 quadruplex telomerase RNA unwinding by the RNA helicase RHAU.</a> Methods Mol Biol. 1259, 125-135 (2015).</li><li>Lattmann, S., Giri, B., Vaughn, J. P., Akman, S. A., Nagamine, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+the+amino+terminal+RHAU-specific+motif+in+the+recognition+and+resolution+of+guanine+quadruplex-RNA+by+the+DEAH-box+RNA+helicase+RHAU.">Role of the amino terminal RHAU-specific motif in the recognition and resolution of guanine quadruplex-RNA by the DEAH-box RNA helicase RHAU.</a> Nucleic Acids Res. 38 (18), 6219-6233 (2010).</li></ol>

作者什么都没有透露。

该协议代表一高效表达，纯化，并定量为DHX36基因产物，G4-Resolvase1（G4R1，也称为RHAU和DHX36）（ 图1）的隔离方案。这个协议利用两个纯化步骤:关于钴亲和珠His标签的亲和纯化和酶纯化上G4-DNA缀合珠。后者步骤是在，它需要在严密的亲和力，特异性高，以及催化退绕的活动，rG4R1具有G4结构优点是唯一的。对G4结构紧亲和性（在低PM范围ķ 四 ）允许高盐洗涤（邻近的NaCl的溶解度极限）之前洗脱从G4珠，大大降低非特异性蛋白的存在。 G4R1对G4结构的催化活性允许活性rG4R1的当加入ATP和MgCl 2的特定溶出。这两步净化方案一贯产生高纯度在适用于大多数生化分析数量的催化活性rG4R1 13。 几个关键步骤将确保高纯度，催化活性rG4R1良好的产量。首先是要保证在细菌表达菌株的His-rG4R1的适当诱导条件。我们已发现，当细胞生长至不超过0.4-0.6之前，为了诱导的OD 600发生重组蛋白质的最佳产率。生长细胞超过此点，可能导致蛋白质回收率的整体的损失，这可能是由于rG4R1掺入包涵体。其次，我们以"串联结合"的裂解物的钴亲和珠得到的纯化蛋白的浓度较高。例如，我们从0.5升诱导的培养，以钴亲和珠的结合的裂解物，然后进行另一裂解物的第二结合从一个附加0.5升培养物以相同的钴亲和珠。这个步骤确保通过增加结合于珠的给定体积rG4R1分子的数目，因此需要利用的钴亲和珠的全部容量蛋白的更浓缩的制剂。第三，钴亲和力洗脱结合到G4珠粒后高盐洗涤确保几乎所有的非特异性蛋白结合至珠被除去。第四，ATP / MgCl 2的洗脱步骤允许rG4R1结合至G4珠粒催化放松的tetramolecular结构成单链，从而导致rG4R1可以从珠释放。我们不能完全排除ATP洗脱rG4R1在竞争，而不是一个催化方式的可能性;然而，这是不太可能的情况下，由于我们先前已经表明，非水解的ATP类似物不足以竞争性结合13,18。 rG4R1为退绕的亲和性，单链DNA是一个数量级小于吨他开始tetramolecular G4-DNA，因此rG4R1不应重新绑定至珠。为了减少这种可能性，然而，该步骤应在37℃下进行，和洗脱体积应该从珠粒尽快分离。洗脱步骤重复两次，以确保最大的回收。如果下游应用要求是自由的DNA污染物的蛋白，我们建议的附加净化步骤，其中所述纯化制品重新结合到链霉抗珠粒，以便如果存在以除去任何生物素化的DNA。 我们已经发现，rG4R1是容易退化，如果在适当的条件不是整个协议保持。为了保持酶的完整性和活性，我们使用以下关键的保障。蛋白酶抑制剂保持整个纯化过程本。该协议是在4℃下进行，除非另有说明。该蛋白质是在1a的存在下进行纯化ctalbumin和β巯基乙醇。该协议是在及时（用于纯化在1天）进行。此外，我们已经发现，多种冻融的蛋白的活性产生不利影响，因此，我们等分蛋白为"一次性使用"7微升等份以下纯化并将其存储在-80℃。 虽然需要乳清蛋白的制剂中的存在，以保持该蛋白质的完整性和活性，如上述提到的，我们已经发现，这还可能妨碍下游应用。其他潜在的干扰分子中存在的纯化rG4R1制剂包括三磷酸腺苷，β巯基乙醇，和单挑链DNA。例如，我们已经发现这种蛋白质制剂必须与BIACORE分析不相容由于从缓冲部件的高背景信号。另外，在蛋白制剂乳清蛋白的存在排除了使用标准布拉德福德和BCA蛋白定量检测。然而，我们已经开发了一种替代基于凝胶的定量方法来规避此限制。 此纯化过程中，它利用G4R1的酶活性作为一种手段来特别净化它，使得这种方法与其他方法不同。例如，其他小组已经在昆虫细胞26表达FLAG标记rG4R1在人类细胞15,25或GST-标记rG4R1和分别FLAG-或GST亲和层析，纯化之。这些方法有在真核表达系统中所做相比，细菌表达系统的优点。发现得到的纯化GST-G4R1为G4结构估计杀敌值是更高的数量级14的订单比我们报道杀敌值12，13。我们的属性THI以Kð数值•差异与一个笨重GST标签与一个带6xHis标签相关联的差异，在翻译后修饰的细菌与所获取的程度和类型在来自这两个纯化方案得到的纯度的差异，以及不同昆虫表达系统。我们的方法具有超过上述替代方案具有明显的优势，因为该蛋白质的纯化在其酶活性直接铰链。因此，我们主要得到已折叠和修饰以维持其酶活性的方式的酶。其它亲和标签和/或大小排阻技术不能活性酶从酶死酶分离。到其他组的净化协议的长处结合15，25，26（ 即人类或昆虫细胞表达这将是对未来协议的开发有用离子系统）与我们的协议（ 即，催化净化基础）的力量，在这种方法进一步提高。 虽然该协议是目前特异性G4R1，它可以容易地适应任何ATP依赖性，G4分辨蛋白，包括，但不限于，博莱霉素，WRN，FANCJ核蛋白蛋白质，hPif1，和/或ChlR1 / DDX1。通过改变核酸结合到链霉抗珠粒的序列，该协议可以适于纯化其它ATP依赖性核酸酶的量，酶反应的产物不再是酶的底物，包括核酸解旋酶和核酸酶。

G4结构是DNA和RNA的富鸟嘌呤区域内形成高度稳定的核酸的二级结构。 G4结构通过Hoogsteen碱基接合相互作用来稳定，并与一价阳离子（ 即 K +和Na +），该显著有助于G4结构1,2的显着热稳定性的中心空腔内坐标粘接。早期的生物信息学研究表明，人类基因组包含&gt; 375000"潜在G4形成的图案"3,4。最近的研究估计表明，G4基序的数目是由2-5 5倍以上，而另一项研究预测在人类基因组6 716310不同电位G4形成的序列。 G4形成序列进化上保守的，而不是随机地分散在基因组中。 G4图案富集基因编码区，以及所有基因启动子的40％以上含有G4图案7。有趣的是，在一个基因的G4基序的富集的程度已被证明表明该基因的功能。例如，参与发展原癌基因和基因比抑癌基因8,9 G4结构显著更大的富集。 具有高的热稳定性，在整个基因组中的几乎无处不在，并且显著影响主要的细胞过程的潜力，这是令人吃惊地发现，细胞已经发展酶来管理这些结构。一种这样的酶是G4 Resolvase1（G4R1;也称作RHAU和DHX36），我们表征为在人类（HeLa细胞）细胞10多数tetramolecular G4-DNA解析活性的来源。自那时以来，它已被证明塔吨G4R1紧密结合并催化开卷tetramolecular和单分子G4-DNA和G4-RNA与用于G4结合蛋白11，12，13中的紧密的报告的KDS。此外，G4R1的G4分辨活性已经牵涉在广泛的生物化学和细胞过程，包括端粒/端粒酶生物学11，14，15，16，转录和剪接17，18，19，20，发展21，造血21，及免疫调节22,23。用G4序列占优势的特别位于整个基因组和不同的对细胞processes该G4R1最近已经牵连用，表达和有效地净化活性高rG4R1将是极为重要的为阐明该蛋白的生化机制和行为的能力有关。 在这里，我们证明了一种新的表达而这需要rG4R1的ATP依赖性，G4-解决活动的优势，以有效地分离活性酶的纯化方案（ 图1）。该方案可以适用于纯化其它ATP依赖性核酸酶的量，酶反应的产物是不再结合的基板，如为G4R1的情况。

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>TriEx4-DHX36 plasmid</td>
			<td>Addgene</td>
			<td>68368</td>
			<td></td>
		</tr>
		<tr>
			<td>Rosetta2(DE3)plysS competent cells</td>
			<td>Novagen</td>
			<td>71403-4</td>
			<td></td>
		</tr>
		<tr>
			<td>S.O.C medium</td>
			<td>Thermo Fisher Scientific</td>
			<td>15544034&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Difco Terrific Broth</td>
			<td>Becton Dickinson</td>
			<td>243820</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Sigma-Aldrich</td>
			<td>G5516</td>
			<td></td>
		</tr>
		<tr>
			<td>Chloramphenicol</td>
			<td>Sigma-Aldrich</td>
			<td>C1919</td>
			<td>35 &#181;g/ml in bacterial plates/large cultures</td>
		</tr>
		<tr>
			<td>Carbenicillin (plant cell culture tested)</td>
			<td>Sigma-Aldrich</td>
			<td>C3416</td>
			<td>50 &#181;g/ml in bacterial plates/large cultures</td>
		</tr>
		<tr>
			<td>Isopropyl &#946;-D-1-thiogalactopyranoside (IPTG)</td>
			<td>Sigma-Aldrich</td>
			<td>I6758</td>
			<td></td>
		</tr>
		<tr>
			<td>Lysozyme (from chicken egg white)</td>
			<td>Sigma-Aldrich</td>
			<td>L6876</td>
			<td></td>
		</tr>
		<tr>
			<td>1 M Tris-HCl pH=8</td>
			<td>Universal Scientific Supply Co.&#160;</td>
			<td>1963-B</td>
			<td>or From standard source</td>
		</tr>
		<tr>
			<td>1 M Tris-HCl pH=7</td>
			<td>Universal Scientific Supply Co.&#160;</td>
			<td>1966</td>
			<td>or From standard source</td>
		</tr>
		<tr>
			<td>1.5 M Tris-HCl, pH=8.8</td>
			<td></td>
			<td></td>
			<td>For casting resolving gel (for protein quantitation gel); From standard source</td>
		</tr>
		<tr>
			<td>1 M Tris-HCl, pH=6.8</td>
			<td></td>
			<td></td>
			<td>For casting stacking gel (for protein quantitation gel); From standard source</td>
		</tr>
		<tr>
			<td>1 M Tris-Acetate, pH=7.8</td>
			<td>Universal Scientific Supply Co.&#160;</td>
			<td>1981</td>
			<td>or From standard source</td>
		</tr>
		<tr>
			<td>70% Ethanol</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>Magnesium chloride (1 M solution)</td>
			<td>Life Technologies</td>
			<td>AM9530G</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium chloride</td>
			<td>Sigma-Aldrich</td>
			<td>S7653</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium acetate</td>
			<td>Sigma-Aldrich</td>
			<td>S8750</td>
			<td></td>
		</tr>
		<tr>
			<td>20x SSC</td>
			<td>Universal Scientific Supply Co.&#160;</td>
			<td>1665</td>
			<td>or From standard source</td>
		</tr>
		<tr>
			<td>&#946;-mercaptoethanol (2-BME)</td>
			<td>Sigma-Aldrich</td>
			<td>63689</td>
			<td></td>
		</tr>
		<tr>
			<td>Protease inhibitor cocktail</td>
			<td>Sigma-Aldrich</td>
			<td>P8849</td>
			<td></td>
		</tr>
		<tr>
			<td>Leupeptin hemisulfate</td>
			<td>Sigma-Aldrich</td>
			<td>L8511</td>
			<td></td>
		</tr>
		<tr>
			<td>Streptavidin paramagnetic beads</td>
			<td>Promega</td>
			<td>Z5482</td>
			<td></td>
		</tr>
		<tr>
			<td>0.5 M EDTA, pH=8&#160;</td>
			<td>Universal Scientific Supply Co.&#160;</td>
			<td>0718</td>
			<td>or From standard source</td>
		</tr>
		<tr>
			<td>0.2 M EDTA, pH=6</td>
			<td>Universal Scientific Supply Co.&#160;</td>
			<td></td>
			<td>From standard source; initially adjust pH with NaOH, then adjust pH back down with HCl.&#160;&#160;</td>
		</tr>
		<tr>
			<td>A-lactalbumin (Type 1 from bovine milk)</td>
			<td>Sigma-Aldrich</td>
			<td>L5385</td>
			<td></td>
		</tr>
		<tr>
			<td>Cobalt metal affinity beads</td>
			<td>Clonetech</td>
			<td>635502</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Histidine</td>
			<td>Sigma-Aldrich</td>
			<td>H8000</td>
			<td></td>
		</tr>
		<tr>
			<td>Acetic acid, glacial</td>
			<td>Fisher Scientific</td>
			<td>A38-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Adenosine 5&#39;-Triphosphate (from bacterial source)</td>
			<td>Sigma</td>
			<td>A7699</td>
			<td></td>
		</tr>
		<tr>
			<td>40% acrylamide/Bis solution (37.5:1)</td>
			<td>Biorad</td>
			<td>161-0148</td>
			<td></td>
		</tr>
		<tr>
			<td>Glycine</td>
			<td>Sigma-Aldrich</td>
			<td>50046</td>
			<td>to make protein gel running buffer (192 mM glycine, 25 mM Tris Base, 0.1% SDS)</td>
		</tr>
		<tr>
			<td>10 % Sodium dodecyl sulfate&#160;</td>
			<td>Universal Scientific Supply Co.&#160;</td>
			<td>1667</td>
			<td>to make protein gel running buffer (192 mM glycine, 25 mM Tris Base, 0.1% SDS); or From standard source</td>
		</tr>
		<tr>
			<td>10x TBE&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>11666703001</td>
			<td>or From standard source</td>
		</tr>
		<tr>
			<td>Tris base</td>
			<td>Fisher Scientific</td>
			<td>BP152-1</td>
			<td>to make protein gel running buffer (192 mM glycine, 25 mM Tris Base, 0.1% SDS); From standard source</td>
		</tr>
		<tr>
			<td>TEMED</td>
			<td>Sigma-Aldrich</td>
			<td>411019</td>
			<td></td>
		</tr>
		<tr>
			<td>Ammonium persulfate</td>
			<td>Sigma-Aldrich</td>
			<td>A3678</td>
			<td></td>
		</tr>
		<tr>
			<td>Broad Range Protein MW markers</td>
			<td>Promega</td>
			<td>V8491</td>
			<td></td>
		</tr>
		<tr>
			<td>Biotinylated Z33 oligo (&#34;Z33-Bio&#34;)</td>
			<td>Oligos Etc</td>
			<td></td>
			<td>5&#8217; AAA GTG ATG GTG GTG GGG GAA GGA TTC GGA CCT-biotin 3&#8217;</td>
		</tr>
		<tr>
			<td>TAMRA-Z33 oligo (&#34;Z33-TAM&#34;)</td>
			<td>Oligos Etc</td>
			<td></td>
			<td>5&#8217; TAMRA-AAA GTG ATG GTG GTG GGG GAA GGA TTC GGA CCT 3&#8217;</td>
		</tr>
		<tr>
			<td>Fluor-coated TLC plate</td>
			<td>Life Technologies</td>
			<td>AM10110</td>
			<td></td>
		</tr>
		<tr>
			<td>Ficoll</td>
			<td>Sigma-Aldrich</td>
			<td>F2637</td>
			<td>30% in H2O</td>
		</tr>
		<tr>
			<td>Coomassie R-250</td>
			<td>Sigma-Aldrich</td>
			<td>27816</td>
			<td></td>
		</tr>
		<tr>
			<td>Methanol</td>
			<td>Fisher Scientific</td>
			<td>A412</td>
			<td></td>
		</tr>
		<tr>
			<td>Multiband UV lamp</td>
			<td></td>
			<td></td>
			<td>Capable of emitting UV light at 365 nm</td>
		</tr>
		<tr>
			<td>Table-top centrifuge (with swinging bucket rotor)</td>
			<td></td>
			<td></td>
			<td>Capable of being cooled to 4 &#176;C</td>
		</tr>
		<tr>
			<td>Microcentrifuge</td>
			<td></td>
			<td></td>
			<td>Capable of being cooled to 4 &#176;C</td>
		</tr>
		<tr>
			<td>Digital Sonfier</td>
			<td>Branson</td>
			<td></td>
			<td>Or equivalent capable of delivering sonication pulses (30% amplitude, 2s ON 2s OFF)</td>
		</tr>
		<tr>
			<td>50 &#176;C water bath</td>
			<td></td>
			<td></td>
			<td>For formation of Z33 into quadruplex</td>
		</tr>
		<tr>
			<td>37 &#176;C incubator for bacteria</td>
			<td></td>
			<td></td>
			<td>For bacterial transformations and initial overnight growth of large cultures of Rosetta2 E. coli transformed with TriEx4-DHX36</td>
		</tr>
		<tr>
			<td>37 &#176;C/14&#160; &#176;C shaking incubator for bacteria</td>
			<td></td>
			<td></td>
			<td>For growth and protein induction of large cultures of Rosetta2 E. coli transformed with TriEx4-DHX36</td>
		</tr>
		<tr>
			<td>Spectrophotometer</td>
			<td></td>
			<td></td>
			<td>capable of reading OD600; capable of reading oligomer concentrations based on base sequence (such as Biorad SmartSpec 3000)</td>
		</tr>
		<tr>
			<td>Thermometer</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>PCR strip tubes</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>15- and 50-ml centrifuge tubes (polypropylene)</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>Microcentrifuge tubes (2.0 ml)</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>500 ml centrifuge bottles (polypropylene)</td>
			<td>Thermo Scientific</td>
			<td>3141-0500</td>
			<td></td>
		</tr>
		<tr>
			<td>Standard array of pipet tips and serological pipettes</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>Gel-loading tips</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>Automatic repeating pipette</td>
			<td></td>
			<td></td>
			<td>For quick aliquoting of rG4R1; From standard source</td>
		</tr>
		<tr>
			<td>Thermal cycler</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>Liquid Nitrogen</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>Dry ice</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>Laemlli sample buffer&#160;</td>
			<td>Biorad</td>
			<td>161-0737</td>
			<td></td>
		</tr>
		<tr>
			<td>Apparatus for running large slab gels</td>
			<td>Biorad</td>
			<td></td>
			<td>We have used the Protean II xi cell apparatus from Biorad</td>
		</tr>
		<tr>
			<td>Magnet</td>
			<td>Life Technologies</td>
			<td>12301D</td>
			<td>We use a magnet from One Lambda (Now a Thermo Fisher Scientific brand); and Life is also a subsidiary of Thermo, and thus the magnet listed here should be a suitable replacement</td>
		</tr>
		<tr>
			<td>Razor blades</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>Filter paper and funnel</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>Glass casserole dish</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>Orbital shaker</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>Kimwipes</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>Clear sheet protectors</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>Scanner and associated TWAIN software</td>
			<td></td>
			<td></td>
			<td>From standard source</td>
		</tr>
		<tr>
			<td>Image analysis software</td>
			<td></td>
			<td></td>
			<td>Such as Fuji Multiguage, or equivalent</td>
		</tr>
		<tr>
			<td>Microsoft Excel</td>
			<td></td>
			<td></td>
			<td>Or equivalent&#160;</td>
		</tr>
	</tbody>
</table>

a g-quadruplex dna-affinity approach for purification of enzymatically active g4 resolvase1

高阶核酸结构称为G-四链（台G4，G4结构）可以在DNA和RNA的富含鸟嘌呤区形成并且是高度热稳定的。有在人类基因组&gt; 375000推定G4形成的序列，它们在启动子区域，非翻译区（UTR）富集和端粒重复内。由于对这些结构以影响细胞过程，如复制和转录的潜力，所述细胞已演变的酶来管理它们。一种这样的酶是G4解离1（G4R1），将其生化共同特征在于我们的实验室和长峰等。并发现极紧到两个G4-DNA和G4-RNA（K d。在低PM范围）结合。 G4R1是多数在HeLa细胞裂解物的G4分辨活性的来源，并一直牵连发挥端粒代谢，淋巴开发，基因转录，造血和免疫监视作用。 EF英孚的能力ficiently表达和纯化催化活性G4R1是重要的，针对有意获得进一步的深入了解G4结构和G4-解决酶的动力学相互作用实验室。在这里，我们描述了重组G4R1（rG4R1）的提纯的详细方法。所描述的过程结合的C-末端组氨酸标记的酶的传统的基于亲和纯化在具有rG4R1的能力利用人密码子优化的细菌中表达结合和放松G4-DNA的纯化高活性酶在ATP的依赖洗脱步骤。该协议还包括其中rG4R1的酶活性是通过检查纯化的酶的放松G4-DNA的能力测得的质量控制步骤。的方法还描述了允许纯化rG4R1的量化。该协议的另类改编进行了讨论。

该协议（ 图1）经常产生几乎纯，催化活性rG4R1。作为酶活性的量度，它通常被观察到，0.2皮摩尔TAMRA标记tetramolecular G4-DNA的50％在0.2内转化成单体- rG4R1 0.013微升范围，由上述（ 图中概述的G4活性测定为测定2）。纯化rG4R1的考马斯染色在约75 kDa的，这可能代表截短rG4R1已保持其结合G4-DNA的珠和在ATP依赖洗脱能力表明在预期120 kDa的大小的单一条带，具有轻微的污染带方式（ 图3）。感兴趣的频带对蛋白质标准曲线定量，该协议通常获得的20-100每1nM的精制酶升对细菌培养的200微升。 <img alt="图1" src="/files/ftp_upload/55496/55496fig1.jpg" /> 图1:G4R1的两步净化的原理。一个6xHis标签rG4R1是批量纯化首先结合并从洗脱钴离子偶联珠从大肠杆菌裂解液。一个绑定步骤G4-DNA结合的磁珠如下。最后，ATP依赖性洗脱步骤是必要的，以获得相对较纯的和酶促活性rG4R1。 <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55496/55496fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图2" src="/files/ftp_upload/55496/55496fig2.jpg" /> 图2:质量控制G4-DNA解旋试验。泳道1 - 6:TAMRA标记tetramolecular G4-DNA的浓度恒定在37℃的纯化rG4R1的4倍系列稀释的代表3.9微升，0.83微升，0.2微升，0.05微升，0.013微升存在下培养30分钟和0<html> 0.003μL，分别为。泳道7:tetramolecular G4-DNA在没有rG4R1的。泳道8:tetramolecular G4-DNA煮沸，以减少在没有rG4R1的G4结构成单体。 <a href="https://ecsource-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/55496/55496fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <img alt="图3" src="/files/ftp_upload/55496/55496fig3.jpg" /> 图3:纯化rG4R1浓度的定量。宽范围分子量蛋白质标志物被装在以下数量:500，250，125，62.5，31.3，和15.7纳克在泳道1 - 分别为6，并用于产生蛋白质浓度的标准曲线。泳道7代表rG4R1的35微升。这个特定的凝胶进行定量，作为一式三份组凝胶的一部分，从而导致62±22纳米标准差的平均蛋白浓度（SD; N = 9）。.COM /文件/ ftp_upload / 55496 / 55496fig3large.jpg"目标="_空白"&gt;点击此处查看该图的放大版本。

Watch this Scientific Journal Video about A G-quadruplex DNA-affinity Approach for Purification of Enzymatically Active G4 Resolvase1 at JoVE.com

A G-quadruplex DNA-affinity Approach for Purification of Enzymatically Active G4 Resolvase1

G4 Resolvase1结合G-四（G4）的结构与一个G4结合蛋白的紧密报道的亲和力，并表示在HeLa细胞中的大多数G4-DNA解旋活动。我们描述了线束的亲和力和G4-Resolvase1的ATP依赖的平仓活动，特别是净化催化活性的重组G4R1一个新的协议。

对酶活性G4 Resolvase1净化用G-四DNA亲和方法

Higher-order nucleic acid structures called G-quadruplexes (G4s, G4 structures) can form in guanine-rich regions of both DNA and RNA and are highly ...

a-g-quadruplex-dna-affinity-approach-for-purification-enzymatically

Nanyang Technological University

Research

JoVE Journal

Biochemistry

9.5K 次观看.  Wake Forest School of Medicine.  G4 Resolvase1结合G-四（G4）的结构与一个G4结合蛋白的紧密报道的亲和力，并表示在HeLa细胞中的大多数G4-DNA解旋活动。我们描述了线束的亲和力和G4-Resolvase1的ATP依赖的平仓活动，特别是净化催化活性的重组G4R1一个新的协议。 

视频: A G-quadruplex DNA-affinity Approach for Purification of Enzymatically Active G4 Resolvase1

Directed Protein Packaging within Outer Membrane Vesicles from Escherichia coli: Design, Production and Purification

An increasing interest in applying synthetic biology techniques to program outer membrane vesicles (OMV) are leading to some very interesting and unique applications for OMV where traditional nanoparticles are proving too difficult to synthesize. To date, all Gram-negative bacteria have been shown to produce OMV demonstrating packaging of a variety of cargo that includes small molecules, peptides, proteins and genetic material. Based on their diverse cargo, OMV are implicated in many biological processes ranging from cell-cell communication to gene transfer and delivery of virulence factors depending upon which bacteria are producing the OMV. Only recently have bacterial OMV become accessible for use across a wide range of applications through the development of techniques to control and direct packaging of recombinant proteins into OMV. This protocol describes a method for the production, purification, and use of enzyme packaged OMV providing for improved overall production of recombinant enzyme, increased vesiculation, and enhanced enzyme stability. Successful utilization of this protocol will result in the creation of a bacterial strain that simultaneously produces a recombinant protein and directs it for OMV encapsulation through creating a synthetic linkage between the recombinant protein and an outer membrane anchor protein. This protocol also details methods for isolating OMV from bacterial cultures as well as proper handling techniques and things to consider when adapting this protocol for use for other unique applications such as: pharmaceutical drug delivery, medical diagnostics, and environmental remediation.

Directed Protein Packaging within Outer Membrane Vesicles from Escherichia coli: Design, Production and Purification

A protocol for the production, purification, and use of enzyme packaged outer membrane vesicles (OMV) providing for enhanced enzyme stability for implementation across diverse applications is presented.

从外膜囊泡内蛋白质导演包装<em&gt;大肠杆菌</em&gt;:设计，生产和纯化

An increasing interest in applying synthetic biology techniques to program outer membrane vesicles (OMV) are leading to some very interesting and unique ...

科研

生物化学

A Facile and Efficient Approach for the Production of Reversible Disulfide Cross-linked Micelles

Nanomedicine is an emerging form of therapy that harnesses the unique properties of particles that are nanometers in scale for biomedical application. Improving drug delivery to maximize therapeutic outcomes and to reduce drug-associated side effects are some of the cornerstones of present-day nanomedicine. Nanoparticles in particular have found a wide application in cancer treatment. Nanoparticles that offer a high degree of flexibility in design, application, and production based on the tumor microenvironment are projected to be more effective with rapid translation into clinical practice. The polymeric micellar nano-carrier is a popular choice for drug delivery applications.
In this article, we describe a simple and effective protocol for synthesizing drug-loaded, disulfide cross-linked micelles based on the self-assembly of a well-defined amphiphilic linear-dendritic copolymer (telodendrimer, TD). TD is composed of polyethylene glycol (PEG) as the hydrophilic segment and a thiolated cholic acid cluster as the core-forming hydrophobic moiety attached stepwise to an amine-terminated PEG using solution-based peptide chemistry. Chemotherapy drugs, such as paclitaxel (PTX), can be loaded using a standard solvent evaporation method. The O2-mediated oxidation was previously utilized to form intra-micellar disulfide cross-links from free thiol groups on the TDs. However, the reaction was slow and not feasible for large-scale production. Recently, an H2O2-mediated oxidation method was explored as a more feasible and efficient approach, and it was 96 times faster than the previously reported method. Using this approach, 50 g of PTX-loaded, disulfide cross-linked nanoparticles have been successfully produced with narrow particle size distribution and high drug loading efficiency. The stability of the resulting micelle solution is analyzed using disrupting conditions such as co-incubation with a detergent, sodium dodecyl sulfate, with or without a reducing agent. The drug-loaded, disulfide cross-linked micelles demonstrated less hemolytic activity when compared to their non-cross-linked counterparts.

To deliver cancer drugs to tumor sites with high specificity and reduced side effects, new methods based on nanoparticles are required. Here, we describe disulfide cross-linked micelles that can be easily prepared by hydrogen peroxide-mediated oxidation and are able to dissociate efficiently under a reducing tumor environment to release payloads.

可逆二硫键交联胶束生产的简便和有效途径

Nanomedicine is an emerging form of therapy that harnesses the unique properties of particles that are nanometers in scale for biomedical application. ...

Expression, Purification, and Antimicrobial Activity of S100A12

Calgranulin proteins are important mediators of innate immunity and are members of the S100 class of the EF-hand family of calcium binding proteins. Some S100 proteins have the capacity to bind transition metals with high affinity and effectively sequester them away from invading microbial pathogens in a process that is termed "nutritional immunity". S100A12 (EN-RAGE) binds both zinc and copper and is highly abundant in innate immune cells such as macrophages and neutrophils. We report a refined method for the expression, enrichment and purification of S100A12 in its active, metal-binding configuration. Utilization of this protein in bacterial growth and viability analyses reveals that S100A12 has antimicrobial activity against the bacterial pathogen, Helicobacter pylori. The antimicrobial activity is predicated on the zinc-binding activity of S100A12, which chelates nutrient zinc, thereby starving H. pylori which requires zinc for growth and proliferation.

Here, we present a method to express and purify S100A12 (calgranulin C). We describe a protocol to measure its antimicrobial activity against the human pathogen H. pylori.

S100A12的表达，纯化和抗菌活性

Calgranulin proteins are important mediators of innate immunity and are members of the S100 class of the EF-hand family of calcium binding proteins. Some ...

Brain Membrane Fractionation: An Ex Vivo Approach to Assess Subsynaptic Protein Localization

Assessing the synaptic protein composition and function constitutes an important challenge in neuroscience. However, it is not easy to evaluate neurotransmission that occurs within synapses because it is highly regulated by dynamic protein-protein interactions and phosphorylation events. Accordingly, when any method is used to study synaptic transmission, a major goal is to preserve these transient physiological modifications. Here, we present a brain membrane fractionation protocol that represents a robust procedure to isolate proteins belonging to different synaptic compartments. In other words, the protocol describes a biochemical methodology to carry out protein enrichment from presynaptic, postsynaptic, and extrasynaptic compartments. First, synaptosomes, or synaptic terminals, are obtained from neurons that contain all synaptic compartments by means of a discontinuous sucrose gradient. Of note, the quality of this initial synaptic membrane preparation is critical. Subsequently, the isolation of the different subsynaptic compartments is achieved with light solubilization using mild detergents at differential pH conditions. This allows for separation by gradient and isopycnic centrifugations. Finally, protein enrichment at the different subsynaptic compartments (i.e., pre-, post- and extrasynaptic membrane fractions) is validated by means of immunoblot analysis using well-characterized synaptic protein markers (i.e., SNAP-25, PSD-95, and synaptophysin, respectively), thus enabling a direct assessment of the synaptic distribution of any particular neuronal protein.

Brain Membrane Fractionation: An Ex Vivo Approach to Assess Subsynaptic Protein Localization

Here, we present a brain membrane fractionation protocol that represents a robust procedure to isolate proteins belonging to different synaptic compartments.

脑膜分离法<em&gt;体检</em评估亚突触蛋白定位的方法

Assessing the synaptic protein composition and function constitutes an important challenge in neuroscience. However, it is not easy to evaluate ...

Method for Efficient Refolding and Purification of Chemoreceptor Ligand Binding Domain

Identification of natural ligands of chemoreceptors and structural studies aimed at elucidation of the molecular basis of the ligand specificity can be greatly facilitated by the production of milligram amounts of pure, folded ligand binding domains. Attempts to heterologously express periplasmic ligand binding domains of bacterial chemoreceptors in Escherichia coli (E. coli) often result in their targeting into inclusion bodies. Here, a method is presented for protein recovery from inclusion bodies, its refolding and purification, using the periplasmic dCACHE ligand binding domain of Campylobacter jejuni (C. jejuni) chemoreceptor Tlp3 as an example. The approach involves expression of the protein of interest with a cleavable His6-tag, isolation and urea-mediated solubilisation of inclusion bodies, protein refolding by urea depletion, and purification by means of affinity chromatography, followed by tag removal and size-exclusion chromatography. The circular dichroism spectroscopy is used to confirm the folded state of the pure protein. It has been demonstrated that this protocol is generally useful for production of milligram amounts of dCACHE periplasmic ligand binding domains of other bacterial chemoreceptors in a soluble and crystallisable form.

A procedure is presented for the refolding of the dCACHE periplasmic ligand binding domain of Campylobacter jejuni chemoreceptor Tlp3 from inclusion bodies and the purification to yield milligram quantities of protein.

化学感受器配体结合域的高效复用与纯化方法

Identification of natural ligands of chemoreceptors and structural studies aimed at elucidation of the molecular basis of the ligand specificity can be ...

Purification and Reconstitution of TRPV1 for Spectroscopic Analysis

Polymodal ion channels transduce multiple stimuli of different natures into allosteric changes; these dynamic conformations are challenging to determine and remain largely unknown. With recent advances in single-particle cryo-electron microscopy (cryo-EM) shedding light on the structural features of agonist binding sites and the activation mechanism of several ion channels, the stage is set for an in-depth dynamic analysis of their gating mechanisms using spectroscopic approaches. Spectroscopic techniques such as electron paramagnetic resonance (EPR) and double electron-electron resonance (DEER) have been mainly restricted to the study of prokaryotic ion channels that can be purified in large quantities. The requirement for large amounts of functional and stable membrane proteins has hampered the study of mammalian ion channels using these approaches. EPR and DEER offer many advantages, including determination of the structure and dynamic changes of mobile protein regions, albeit at low resolution, that might be difficult to obtain by X-ray crystallography or cryo-EM, and monitoring reversible gating transition (i.e., closed, open, sensitized, and desensitized). Here, we provide protocols for obtaining milligrams of functional detergent-solubilized transient receptor potential cation channel subfamily V member 1 (TRPV1) that can be labeled for EPR and DEER spectroscopy.

This article describes specific methods to obtain biochemical quantities of detergent-solubilized TRPV1 for spectroscopic analysis. The combined protocols provide biochemical and biophysical tools that can be adapted to facilitate structural and functional studies for mammalian ion channels in a membrane-controlled environment.

光谱分析 TRPV1 的纯化与重构

Polymodal ion channels transduce multiple stimuli of different natures into allosteric changes; these dynamic conformations are challenging to determine ...

Anaerobic Protein Purification and Kinetic Analysis via Oxygen Electrode for Studying DesB Dioxygenase Activity and Inhibition

Oxygen-sensitive proteins, including those enzymes which utilize oxygen as a substrate, can have reduced stability when purified using traditional aerobic purification methods. This manuscript illustrates the technical details involved in the anaerobic purification process, including the preparation of buffers and reagents, the methods for column chromatography in a glove box, and the desalting of the protein prior to kinetics. Also described are the methods for preparing and using an oxygen electrode to perform kinetic characterization of an oxygen-utilizing enzyme. These methods are illustrated using the dioxygenase enzyme DesB, a gallate dioxygenase from the bacterium Sphingobium sp. strain SYK-6.

Here we present a protocol for anaerobic protein purification, anaerobic protein concentration, and subsequent kinetic characterization using an oxygen electrode system. The method is illustrated using the enzyme DesB, a dioxygenase enzyme which is more stable and active when purified and stored in an anaerobic environment.

氧电极对 DesB 酶活性和抑制作用的厌氧蛋白纯化及动力学分析

Oxygen-sensitive proteins, including those enzymes which utilize oxygen as a substrate, can have reduced stability when purified using traditional aerobic ...

Expression and Purification of Nuclease-Free Oxygen Scavenger Protocatechuate 3,4-Dioxygenase

Single molecule (SM) microscopy is used in the study of dynamic molecular interactions of fluorophore labeled biomolecules in real time. However, fluorophores are prone to loss of signal via photobleaching by dissolved oxygen (O2). To prevent photobleaching and extend the fluorophore lifetime, oxygen scavenging systems (OSS) are employed to reduce O2. Commercially available OSS may be contaminated by nucleases that damage or degrade nucleic acids, confounding interpretation of experimental results. Here we detail a protocol for the expression and purification of highly active Pseudomonas putida protocatechuate-3,4-dioxygenase (PCD) with no detectable nuclease contamination. PCD can efficiently remove reactive O2 species by conversion of the substrate protocatechuic acid (PCA) to 3-carboxy-cis,cis-muconic acid. This method can be used in any aqueous system where O2 plays a detrimental role in data acquisition. This method is effective in producing highly active, nuclease free PCD in comparison with commercially available PCD.

Protocatechuate 3,4-dioxygenase (PCD) can enzymatically remove free diatomic oxygen from an aqueous system using its substrate protocatechuic acid (PCA). This protocol describes the expression, purification, and activity analysis of this oxygen scavenging enzyme.

无核酸酶的表达和纯化原氧基质 3，4-二氧酶

Single molecule (SM) microscopy is used in the study of dynamic molecular interactions of fluorophore labeled biomolecules in real time. However, ...

A Customizable Approach for the Enzymatic Production and Purification of Diterpenoid Natural Products

Diterpenoids form a diverse class of small molecule natural products that are widely distributed across the kingdoms of life and have critical biological functions in developmental processes, interorganismal interactions, and environmental adaptation. Due to these various bioactivities, many diterpenoids are also of economic importance as pharmaceuticals, food additives, biofuels, and other bioproducts. Advanced genomics and biochemical approaches have enabled a rapid increase in the knowledge of diterpenoid-metabolic genes, enzymes, and pathways. However, the structural complexity of diterpenoids and the narrow taxonomic distribution of individual compounds in often only a single species remain constraining factors for their efficient production. Availability of a broader range of metabolic enzymes now provide resources for producing diterpenoids in sufficient titers and purity to facilitate a deeper investigation of this important metabolite group. Drawing on established tools for microbial and plant-based enzyme co-expression, we present an easily operated and customizable protocol for the enzymatic production of diterpenoids in either Escherichia coli or Nicotiana benthamiana, and the purification of desired products via silica chromatography and semi-preparative HPLC. Using the group of maize (Zea mays) dolabralexin diterpenoids as an example, we highlight how modular combinations of diterpene synthase (diTPS) and cytochrome P450 monooxygenase (P450) enzymes can be used to generate different diterpenoid scaffolds. Purified compounds can be used in various downstream applications, such as metabolite structural analyses, enzyme structure-function studies, and in vitro and in planta bioactivity experiments.

Here we present easy to use protocols for producing and purifying diterpenoid metabolites through the combinatorial expression of biosynthetic enzymes in Escherichia coli or Nicotiana benthamiana, followed by chromatographic product purification. The resulting metabolites are suitable for various studies including molecular structure characterization, enzyme functional studies, and bioactivity assays.

一种可定制的酶化生产与纯化天然产物的方法

Diterpenoids form a diverse class of small molecule natural products that are widely distributed across the kingdoms of life and have critical biological ...

Single Cell Analysis Of Transcriptionally Active Alleles By Single Molecule FISH

Gene transcription is an essential process in cell biology, and allows cells to interpret and respond to internal and external cues. Traditional bulk population methods (Northern blot, PCR, and RNAseq) that measure mRNA levels lack the ability to provide information on cell-to-cell variation in responses. Precise single cell and allelic visualization and quantification is possible via single molecule RNA fluorescence in situ hybridization (smFISH). RNA-FISH is performed by hybridizing target RNAs with labeled oligonucleotide probes. These can be imaged in medium/high throughput modalities, and, through image analysis pipelines, provide quantitative data on both mature and nascent RNAs, all at the single cell level. The fixation, permeabilization, hybridization and imaging steps have been optimized in the lab over many years using the model system described herein, which results in successful and robust single cell analysis of smFISH labeling. The main goal with sample preparation and processing is to produce high quality images characterized by a high signal-to-noise ratio to reduce false positives and provide data that are more accurate. Here, we present a protocol describing the pipeline from sample preparation to data analysis in conjunction with suggestions and optimization steps to tailor to specific samples.&#160;

Single molecule RNA fluorescence in situ hybridization (smFISH) is a method to accurately quantify levels and localization of specific RNAs at the single cell level. Here, we report our validated lab protocols for wet-bench processing, imaging and image analysis for single cell quantification of specific RNAs.

单分子鱼的转录活性等位基因单细胞分析

Gene transcription is an essential process in cell biology, and allows cells to interpret and respond to internal and external cues. Traditional bulk ...