Name: analysis of athird11 intrinsic disorder and binding towards metal ions by capillary gel electrophoresis and affinity capillary electrophoresis
Uploaded: 2018-08-22T14:30:00
Description: Watch this Scientific Journal Video about Analysis of AtHIRD11 Intrinsic Disorder and Binding Towards Metal Ions by Capillary Gel Electrophoresis and Affinity Capillary Electrophoresis at JoVE.com

We grateful thank Masakuza Hara (the Research Institute of Green Science and Technology, University of Shizuoka, Japan) for providing the AtHIRD11 protein samples.

1. Preparation of the Capillary Electrophoresis Instruments
<ol>
	<li>Prepare the capillaries
	<ol>
		<li>Use a glass cutter to cut a bare-fused silica capillary with a polyimide external coating and an inner diameter of 50 &#181;m into 33 cm (for the CGE experiment) and 30 cm (for the ACE experiment) long capillaries. Perform the cutting on a glass plate. 
		Note: The 2 different experimental setups were developed for 2 different instruments. In order to use them on other instruments, a proper me...

<ol>
	<li>Hara, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+multifunctionality+of+dehydrins:+An+overview.">The multifunctionality of dehydrins: An overview.</a> Plant Signaling &amp; Behavior. 5 (5), 1-6 (2010).</li><li>Uversky, V. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dancing+protein+clouds:+the+strange+biology+and+chaotic+physics+of+intrinsically+disordered+proteins.">Dancing protein clouds: the strange biology and chaotic physics of intrinsically disordered proteins.</a> Journal of Biological Chemistry. 291 (13), 6681-6688 (2016).</li><li>Hara, M., 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=Biochemical+characterization+of+the+Arabidopsis+KS-type+dehydrin+protein,+whose+gene+expression+is+constitutively+abundant+rather+than+stress+dependent.">Biochemical characterization of the Arabidopsis KS-type dehydrin protein, whose gene expression is constitutively abundant rather than stress dependent.</a> Acta Physiologia Plantarum. 33 (6), 2103-2116 (2011).</li><li>Nachbar, M., 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=Metal+ion+-+dehydrin+interactions+investigated+by+affinity+capillary+electrophoresis+and+computer+models.">Metal ion - dehydrin interactions investigated by affinity capillary electrophoresis and computer models.</a> Journal of Plant Physiology. 216, 219-228 (2017).</li><li>Alhazmi, H. 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=A+comprehensive+platform+to+investigate+protein-metal+ion+interactions+by+affinity+capillary+electrophoresis.">A comprehensive platform to investigate protein-metal ion interactions by affinity capillary electrophoresis.</a> Journal of Pharmaceutical and Biomedical Analysis. 107, 311-317 (2015).</li><li>Redweik, S., Xu, Y., W&#228;tzig, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Precise,+fast,+and+flexible+determination+of+protein+interactions+by+affinity+capillary+electrophoresis:+Part+1:+Performance.">Precise, fast, and flexible determination of protein interactions by affinity capillary electrophoresis: Part 1: Performance.</a> ELECTROPHORESIS. 33 (22), 3316-3322 (2012).</li><li>Ghosal, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrokinetic+flow+and+dispersion+in+capillary+electrophoresis.">Electrokinetic flow and dispersion in capillary electrophoresis.</a> Annual Review of Fluid Mechanics. 38 (1), 309-338 (2006).</li><li>Xuan, X., Li, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analytical+study+of+Joule+heating+effects+on+electrokinetic+transportation+in+capillary+electrophoresis.">Analytical study of Joule heating effects on electrokinetic transportation in capillary electrophoresis.</a> Journal of Chromatography A. 1064 (2), 227-237 (2005).</li><li>Oledzka, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+evaluation+of+tissue+protein+separations+applying+one-+dimensional+gel+electrophoresis+and+capillary+gel+electrophoresis.">Comparative evaluation of tissue protein separations applying one- dimensional gel electrophoresis and capillary gel electrophoresis.</a> The Open Proteomics Journal. 5 (1), 17-21 (2012).</li><li>Alhazmi, H. 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=Optimization+of+affinity+capillary+electrophoresis+for+routine+investigations+of+protein-metal+ion+interactions.">Optimization of affinity capillary electrophoresis for routine investigations of protein-metal ion interactions.</a> Journal of Separation Science. 38 (20), 3629-3637 (2015).</li><li>Busch, M. H. A., Carels, L. B., Boelens, H. F. M., Kraak, J. C., Poppe, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+five+methods+for+the+study+of+drug-protein+binding+in+affinity+capillary+electrophoresis.">Comparison of five methods for the study of drug-protein binding in affinity capillary electrophoresis.</a> Journal of Chromatography A. 777 (2), 311-328 (1997).</li><li>Mozafari, M., Balasupramaniam, S., Preu, L., El Deeb, S., Reiter, C. G., W&#228;tzig, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Using+affinity+capillary+electrophoresis+and+computational+models+for+binding+studies+of+heparinoids+with+P-selectin+and+other+proteins.">Using affinity capillary electrophoresis and computational models for binding studies of heparinoids with P-selectin and other proteins.</a> ELECTROPHORESIS. 38 (12), 1560-1571 (2017).</li></ol>

For all CE experiments, the preparation of the capillary is a critical step. Since it is a glass tube with a small diameter, it can easily break at the spots where the coating is removed when it is being handled. The installation of the capillary into the instrument should be done very carefully.
The critical steps involved in using the ACE method mainly pertain to the experimental setup. Another critical step is finding the right sample injection parameters. The injected amount of the sample ...

Plants are more dependent on their environment than many other life forms. Since plants cannot move to other places, they have to adjust to changes in their surroundings (e.g., drought, cold and high salt concentrations). Consequently, higher plants developed specialized stress proteins like dehydrins, which fulfill manifold tasks to reduce cell stress related to high salinity. These proteins bind water and ions inside cells, reduce oxidative stress by binding Cu2+-ions, and interact with phospholipids as well as the cytoskeletons. Moreover, binding Zn2+-ions allows these proteins to act as transcription factors. Their ability to bind Ca2+-ions after phosphorylation has also been reported1.
The multifunctional behavior of these proteins is related to the absence of hydrophobic amino acid residues. Consequently, they lack any hydrophobic interactions inside the peptide chain and also a constrained structure. However, because these proteins lack a restrictive structure, they can occupy different conformers under the same conditions. Therefore, they can be described best as an ensemble of structures rather than as a single conformation. Proteins with these properties are known as intrinsically disordered proteins (IDPs) and are a widely used concept for stress proteins and crosstalk between different pathways in eukaryotic cells2.
One of these stress-related IDPs is AtHIRD11. It is one of Arabidopsis thaliana&#39;s most highly drought-expressed IDPs. Hence, the different conformers can be separated by their effective radius to charge ratio, and capillary electrophoresis (CE) has been used for further investigations. Previous ACE experiments demonstrated the interactions between AtHIRD11 and transition metal ions such as Cu2+-, Zn2+-, Co2+, and Ni2+-ions. The detailed results can be found in Hara et al.3 and Nachbar et al.4.
The ACE method that will be used here is based on our earlier published works6. However, the addition of the EOF marker acetanilide to the protein sample is not suitable. AtHIRD11 shows broad peak patterns, and adding the EOF marker to the sample would disguise two peaks. Therefore, the marker is used in a separate run. Before the binding behavior is examined, it is confirmed that the peaks found during previous experiments are from different conformers. Thus, CGE is used to distinguish between the protein conformers, the post-translational modified protein, and impurities, such as fragments of AtHIRD11, by their different masses. Subsequently, the characterized AtHIRD11 sample&#39;s binding behavior towards various different metal ions is investigated.
The purpose of this article is to describe an experimental setup to distinguish between an IDP and other components of a sample in order to evaluate the differences in the binding behavior of different conformers.

<table border="0" cellpadding="0" cellspacing="0" width="638">
	<tbody>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">AtHIRD11 sample</td>
			<td style="width:111px;">Shizuoka University (Group Prof. M. Hara)</td>
			<td style="width:119px;">-</td>
			<td style="width:192px;">Dehydrin Protein from Arabidopsis thaliana expressed in Escherichia coli</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Barefused silica capillary</td>
			<td style="width:111px;">Polymicro Technologies (Phoenix, USA)</td>
			<td style="width:119px;">106815-0017</td>
			<td style="width:192px;">TSP050375, 50 &#956;m inner diameter, 363 &#956;m outer diameter, polyimide coating</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Agilent 1600A</td>
			<td style="width:111px;">Agilent Technologies (Waldbronn, Germany)</td>
			<td style="width:119px;">comercially not available anymore</td>
			<td style="width:192px;">Capillary electrophoresis instrument; Agilent 7100 CE can be used instead</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Agilent 7100 CE</td>
			<td style="width:111px;">Agilent Technologies (Waldbronn, Germany)</td>
			<td style="width:119px;">G7100A</td>
			<td style="width:192px;">Capillary electrophoresis instrument</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Injekt 2 mL</td>
			<td style="width:111px;">B. Braun (Melsungen, Germany)</td>
			<td style="width:119px;">4606051V</td>
			<td style="width:192px;">Syringe for filtration</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Rotilabo-syringe filters</td>
			<td style="width:111px;">Carl Roth GmbH + Co. KG (Karlsruhe, Germany)</td>
			<td style="width:119px;">KY62.1</td>
			<td style="width:192px;">PVDF membrane filter for solution filtration</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Eppendorf Research plus 10 &#956;L</td>
			<td style="width:111px;">Eppendorf (Wesseling-Berzdorf, Germany)</td>
			<td style="width:119px;">3121 000.023</td>
			<td style="width:192px;">Micro pipette for sample handling</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Eppendorf Research plus 10 &#956;L</td>
			<td style="width:111px;">Eppendorf (Wesseling-Berzdorf, Germany)</td>
			<td style="width:119px;">3121 000.120</td>
			<td style="width:192px;">Micro pipette for handling the ligand solutions</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Bulb pipette 10 mL</td>
			<td style="width:111px;">Duran Group GmbH(Mainz, Germany)</td>
			<td style="width:119px;">24 338 08</td>
			<td style="width:192px;">Preparing theNaOH solution</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Bulb pipette 25 mL</td>
			<td style="width:111px;">Duran Group GmbH(Mainz, Germany)</td>
			<td style="width:119px;">24 338 14</td>
			<td style="width:192px;">Preparing the ligand solution</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Duran glas volumetric flask 25 mL</td>
			<td style="width:111px;">Duran Group GmbH(Mainz, Germany)</td>
			<td style="width:119px;">24 671 1457</td>
			<td style="width:192px;">Preparing the ligand stock solution</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Duran glas volumetric flask 10 mL</td>
			<td style="width:111px;">Duran Group GmbH(Mainz, Germany)</td>
			<td style="width:119px;">24 671 1054</td>
			<td style="width:192px;">Preparing the ligand stock solution</td>
		</tr>
		<tr height="147">
			<td height="147" style="height:147px;width:216px;">Proteome Lab SDS MW Gel Buffer</td>
			<td style="width:111px;">Beckman Coulter (Brea, USA)</td>
			<td style="width:119px;">comercially not available anymore</td>
			<td style="width:192px;">Separation during capillary gel electrophoresis / Alternative SDS buffer: CE-SDS run buffer from Bio-Rad Laboratories (M&#252;nchen, Germany) Catalog Number: 1485032&#160;</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Acetanilide</td>
			<td style="width:111px;">Sigma-Aldrich (Steinheim, Germany)</td>
			<td style="width:119px;">397229-5G</td>
			<td style="width:192px;">Electroosmotic flow marker</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Manganese(II) chloride</td>
			<td style="width:111px;">Sigma-Aldrich (Steinheim, Germany)</td>
			<td style="width:119px;">13217</td>
			<td style="width:192px;">Ligand</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Ethylenediaminetetraacetic acid (EDTA)</td>
			<td style="width:111px;">Sigma-Aldrich (Steinheim, Germany)</td>
			<td style="width:119px;">431788-100G</td>
			<td style="width:192px;">Rinsing ingredient</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Bariumchloride</td>
			<td style="width:111px;">Sigma-Aldrich (Steinheim, Germany)</td>
			<td style="width:119px;">202738-5G</td>
			<td style="width:192px;">Ligand</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Sodium dodecyl sulfate</td>
			<td style="width:111px;">Sigma-Aldrich (Steinheim, Germany)</td>
			<td style="width:119px;">71729-100G</td>
			<td style="width:192px;">Solublizing protein for capillary gel electrophoresis</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Nickel(II) chloride hexahydrate</td>
			<td style="width:111px;">Sigma-Aldrich (Steinheim, Germany)</td>
			<td style="width:119px;">654507-5G</td>
			<td style="width:192px;">Ligand</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Selenium(IV) chloride</td>
			<td style="width:111px;">Sigma-Aldrich (Steinheim, Germany)</td>
			<td style="width:119px;">323527-10G</td>
			<td style="width:192px;">Ligand</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">2-amino-2-hydroxy-methylpropane-1.3-diol (Tris)</td>
			<td style="width:111px;">Sigma-Aldrich (Steinheim, Germany)</td>
			<td style="width:119px;">252859-100G</td>
			<td style="width:192px;">Buffer ingredient</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Zinc(II) chloride</td>
			<td style="width:111px;">Merck Millipore ( Darmstadt, Germany)</td>
			<td style="width:119px;">1088160250</td>
			<td style="width:192px;">Ligand</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Strontium nitrate</td>
			<td style="width:111px;">Merck Millipore ( Darmstadt, Germany)</td>
			<td style="width:119px;">1078720250</td>
			<td style="width:192px;">Ligand</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Calcium chloride dihydrate</td>
			<td style="width:111px;">Merck Millipore ( Darmstadt, Germany)</td>
			<td style="width:119px;">1371015000</td>
			<td style="width:192px;">Ligand</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">37% hydrochloric acid</td>
			<td style="width:111px;">Merck Millipore ( Darmstadt, Germany)</td>
			<td style="width:119px;">1003171000</td>
			<td style="width:192px;">Adjusting pH</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Copper(II) chloride dihydrate</td>
			<td style="width:111px;">Riedel-de Ha&#235;n (Seelze, Germany)</td>
			<td style="width:119px;">31286</td>
			<td style="width:192px;">Ligand</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Sonorex Longlife RK 1028 CH 45L</td>
			<td style="width:111px;">Allpax (Papenburg, Germany)</td>
			<td style="width:119px;">10000084;0</td>
			<td style="width:192px;">Ultrasonic bath</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Agilent ChemStation Rev. 8.04.03-SP1</td>
			<td style="width:111px;">Agilent Technologies (Waldbronn, Germany)</td>
			<td>G2070-91126</td>
			<td style="width:192px;">Software packages to operate the CE instruments, acquisite data and evaluate it</td>
		</tr>
	</tbody>
</table>

analysis of athird11 intrinsic disorder and binding towards metal ions by capillary gel electrophoresis and affinity capillary electrophoresis

Plants are strongly dependent on their environment. In order to adjust to stressful changes (e.g., drought and high salinity), higher plants evolve classes of intrinsically disordered proteins (IDPs) to reduce oxidative and osmotic stress. This article uses a combination of capillary gel electrophoresis (CGE) and mobility shift affinity electrophoresis (ACE) in order to describe the binding behavior of different conformers of the IDP AtHIRD11 from Arabidopsis thaliana. CGE is used to confirm the purity of AtHIRD11 and to exclude fragments, posttranslational modifications, and other impurities as reasons for complex peak patterns. In this part of the experiment, the different sample components are separated by a viscous gel inside a capillary by their different masses and detected with a diode array detector. Afterward, the binding behavior of the sample towards various metal ions is investigated by ACE. In this case, the ligand is added to the buffer solution and the shift in migration time is measured in order to determine whether a binding event has occurred or not. One of the advantages of using the combination of CGE and ACE to determine the binding behavior of an IDP is the possibility to automate the gel electrophoresis and the binding assay. Furthermore, CGE shows a lower limit of detection than the classical gel electrophoresis and ACE is able to determine the manner of binding a ligand in a fast manner. In addition, ACE can also be applied to other charged species than metal ions. However, the use of this method for binding experiments is limited in its ability to determine the number of binding sites. Nevertheless, the combination of CGE and ACE can be adapted for characterizing the binding behavior of any protein sample towards numerous charged ligands.

Figure 1 shows the electropherogram for the AtHIRD11 sample obtained during the CGE experiments. The peptide size increases from left to right. Peak number 4 has the largest mass and indicates the intact protein. The smaller peaks 2 and 3 represent smaller impurities (e.g., degradation products). The first peak and the inconsistency of the baseline before could also be reproduced without the protein sample. Therefore, it is related to the SDS gel its...

Watch this Scientific Journal Video about Analysis of AtHIRD11 Intrinsic Disorder and Binding Towards Metal Ions by Capillary Gel Electrophoresis and Affinity Capillary Electrophoresis at JoVE.com

Analysis of AtHIRD11 Intrinsic Disorder and Binding Towards Metal Ions by Capillary Gel Electrophoresis and Affinity Capillary Electrophoresis

This protocol combines the characterization of a protein sample by capillary gel electrophoresis and a fast-binding screening for charged ligands by affinity capillary electrophoresis. It is recommended for proteins with a flexible structure, such as intrinsically disordered proteins, to determine any differences in binding for different conformers.

Plants are strongly dependent on their environment. In order to adjust to stressful changes (e.g., drought and high salinity), higher plants evolve ...

This method can help answering key questions regarding in tectonics of intrinsic disorder proteins such as conformational changes due to metal iron binding. The main advantage of this technique is that it requires very little equipment and the results can be obtained very quickly. Demonstrating the procedure will be Matthias Stein, a grad student from my laboratory.To begin, use a glass cutter on a glass plate to cut a bare fused silica capillary with a polyamide external coating and an inner diameter of 50 microns into 33 and 30 centimeter lengths. Use a pen to mark the middle of a one centimeter wide detection window at a distance of 24.5 centimeters from one end of the capillary for the CGE experiment and at 21.5 centimeters from one end of the capillary for the ACE experiment. Using a blowtorch, burn off the polyamide external coating 0.5 centimeters before and after each mark.Similarly, use the blowtorch to remove one centimeter of the coating at both ends of the capillaries. Then, use ethanol and a soft tissue to clean the ends of the capillaries and the detection windows. Install a capillary into the CE system with the detection window near the outlet.After preparing solutions, according to the text protocol, use 250 micromolar calcium chloride solution to fill a 10 milliliter syringe. Then attach a 0.2 micron PVDF filter to the syringe and push 2 milliliters of the solution through the filter to discard it. Use the remaining calcium chloride in the syringe to fill 10 vials up to the maximum allowed volume.Label each vial as 250 micromolar calcium chloride solution inlet vial. Next, using the calcium chloride solution, fill 10 vials halfway. Mark each as 250 micromolar calcium chloride solution outlet vial.Then, with other metal salt containing solutions, fill vials in a similar manner. In addition, for each pair of inlet and outlet vials, use 30 micromolar Tris Buffer to prepare a similar set of inlet and outlet vials. With 60 micromolar acetanilide EOF marker, fill 10 vials.Then use the one milligram per milliliter sample solution to fill one vial. After preparing the analysis, according to the text protocol, run the separation by hydrodynamically injecting the sample solution for the CGE experiments and applying 0.1 bar for four minutes at the inlet. Then, apply negative 16.5 kilovolts and a pressure of 2.0 bar at both ends of the capillary for 25 minutes.After preparing the method for the measurements without ligands, prepare the method for the measurements with ligands by first using 0.1 molar EDTA solution to rinse the capillary at 2.5 bar for 1 minute. Then use deionized water to rinse the capillary. Next, equilibrate the capillary by using ligand solution to rinse it at 2.5 bar for 1.5 minutes.Then, inject the acetanilide solution at 0.05 bar for 6 seconds and change the inlet and outlet vials to the ligand containing buffer vials. Apply 0.05 bar for 2.4 seconds in order to push the acetanilide solution further in from the tip of the capillary. Apply 10.0 kilovolts for 6 minutes and detect the asset acetanilide peak at a wavelength of 200 nanometers.After rinsing the capillary with EDTA deionized water and the ligand solution, as before, inject the protein sample and change the inlet and outlet vials to fresh ligand containing buffer vials. Alternately, repeat taking measurements with and without ligands. Then, repeat the method using the alkaline earth ligand solutions.Finally, use the following solutions to carry out the same method. Then, calculate the change in charge size ratios for the various protein metal ion interactions. Shown here is the electropherogram for the AtHIRD11 sample obtained during the CGE experiments.The peptide size increases from left to right. Peak number four has the largest mass and indicates the intact protein. The smaller peaks, two and three, represent smaller impurities.This figure represents the electropherogram for acetanilide during the ACE experiments. The acetanilide solution shows only one high peak since it should have no impurities. The detection time for the peak maximum indicates the migration time of the electroosmotic flow and is used for the calculation of the interaction.This electropherogram of the AtHIRD11 sample during the ACE experiment was performed in the absence of SDS and metal ions. Besides the two impurities from the CGE electropherogram, at least five peaks, which are related to the protein itself, are present. A graphical evaluation of the measured migration time shifts in the presence of the various metal ions for peak six, is shown here.It is represented by the calculated value Delta R over RF.Each result indicates how strong of a shift has occurred by its value and its sign as indicated by the overall change in charge of the protein metal ion complexes. Once mastered, the technique can be done for one interaction partner in eight hours including the CGE interaction if it's performed properly. While attempting this procedure, it is important to remember to change the protein solutions for long time measurements since degradation products can increase over time and to change the Tris Buffer solutions in order to obtain more precise results.After watching this video, you should have a good understanding of how to cut and clean a capillary, as well as, set up an affinity capillary electrophoresis method, in order to evaluate the binding behavior of intrinsic disordered proteins.

analysis-athird11-intrinsic-disorder-binding-towards-metal-ions

Research

JoVE Journal

Biochemistry

Sheathless Capillary Electrophoresis&#8211;Mass Spectrometry for Metabolic Profiling of Biological Samples

In metabolomics, a wide range of analytical techniques is used for the global profiling of (endogenous) metabolites in complex samples. In this paper, a protocol is presented for the analysis of anionic and cationic metabolites in biological samples by capillary electrophoresis&#8211;mass spectrometry (CE-MS). CE is well-suited for the analysis of highly polar and charged metabolites as compounds are separated on the basis of their charge-to-size ratio. A recently developed sheathless interfacing design, i.e., a porous tip interface, is used for coupling CE to electrospray ionization (ESI) MS. This interfacing approach allows the effective use of the intrinsically low-flow property of CE in combination with MS, resulting in nanomolar detection limits for a broad range of polar metabolite classes. The protocol presented here is based on employing a bare fused-silica capillary with a porous tip emitter at low-pH separation conditions for the analysis of a broad array of metabolite classes in biological samples. It is demonstrated that the same sheathless CE-MS method can be used for the profiling of cationic metabolites, including amino acids, nucleosides and small peptides, or anionic metabolites, including sugar phosphates, nucleotides and organic acids, by only switching the MS detection and separation voltage polarity. Highly information-rich metabolic profiles in various biological samples, such as urine, cerebrospinal fluid and extracts of the glioblastoma cell line, can be obtained by this protocol in less than 1 hr of CE-MS analysis.

Sheathless Capillary Electrophoresis&amp;#8211;Mass Spectrometry for Metabolic Profiling of Biological Samples

A protocol for metabolic profiling of biological samples by capillary electrophoresis&#8211;mass spectrometry using a sheathless porous tip interface design is presented.

In metabolomics, a wide range of analytical techniques is used for the global profiling of (endogenous) metabolites in complex samples. In this paper, a ...

Characterization of Multi-subunit Protein Complexes of Human MxA Using Non-denaturing Polyacrylamide Gel-electrophoresis

The formation of oligomeric complexes is a crucial prerequisite for the proper structure and function of many proteins. The interferon-induced antiviral effector protein MxA exerts a broad antiviral activity against many viruses. MxA is a dynamin-like GTPase and has the capacity to form oligomeric structures of higher order. However, whether oligomerization of MxA is required for its antiviral activity is an issue of debate. We describe here a simple protocol to assess the oligomeric state of endogenously or ectopically expressed MxA in the cytoplasmic fraction of human cell lines by non-denaturing polyacrylamide gel electrophoresis (PAGE) in combination with Western blot analysis. A critical step of the protocol is the choice of detergents to prevent aggregation and/or precipitation of proteins particularly associated with cellular membranes such as MxA, without interfering with its enzymatic activity. Another crucial aspect of the protocol is the irreversible protection of the free thiol groups of cysteine residues by iodoacetamide to prevent artificial interactions of the protein. This protocol is suitable for a simple assessment of the oligomeric state of MxA and furthermore allows a direct correlation of the antiviral activity of MxA interface mutants with their respective oligomeric states.

This article describes a simple and rapid protocol to evaluate the oligomeric state of the dynamin-like GTPase MxA protein from lysates of human cells using a combination of non-denaturing PAGE with western blot analysis.

The formation of oligomeric complexes is a crucial prerequisite for the proper structure and function of many proteins. The interferon-induced antiviral ...

Capillary Electrophoresis Separation of Monoclonal Antibody Isoforms Using a Neutral Capillary

Biotherapeutic proteins, such as monoclonal antibodies (mAbs), are feasible alternatives for the treatment of chronic-degenerative diseases. The biological activity of these proteins depends on their physicochemical properties. The use of high-performance techniques like chromatography and capillary electrophoresis has been described for the analysis of physicochemical heterogeneity of mAbs. Nowadays, capillary zone electrophoresis (CZE) technique constitutes one of the most resolutive and sensitive assays for the analysis of biomolecules. Besides, the electro-driven separation in CZE is governed by extensive properties of matter and offers the advantage of analyzing proteins close to their native state. However, the successful implementation of this technique for routine analysis depends on the skills of the analyst at the critical steps during sample and system preparation. The purpose of this tutorial is to detail the steps to succeed in the CZE analysis of mAbs. Further, this protocol can be used for the development and improvement of skills of the personnel involved in protein analytical chemistry laboratories.

Here, we present a comprehensive capillary zone electrophoresis protocol for the assessment of intrinsic physicochemical heterogeneity of monoclonal antibodies as a quality attribute.

Biotherapeutic proteins, such as monoclonal antibodies (mAbs), are feasible alternatives for the treatment of chronic-degenerative diseases. The ...

Analyzing Supercomplexes of the Mitochondrial Electron Transport Chain with Native Electrophoresis, In-gel Assays, and Electroelution

The mitochondrial electron transport chain (ETC) transduces the energy derived from the breakdown of various fuels into the bioenergetic currency of the cell, ATP. The ETC is composed of 5 massive protein complexes, which also assemble into supercomplexes called respirasomes (C-I, C-III, and C-IV) and synthasomes (C-V) that increase the efficiency of electron transport and ATP production. Various methods have been used for over 50 years to measure ETC function, but these protocols do not provide information on the assembly of individual complexes and supercomplexes. This protocol describes the technique of native gel polyacrylamide gel electrophoresis (PAGE), a method that was modified more than 20 years ago to study ETC complex structure. Native electrophoresis permits the separation of ETC complexes into their active forms, and these complexes can then be studied using immunoblotting, in-gel assays (IGA), and purification by electroelution. By combining the results of native gel PAGE with those of other mitochondrial assays, it is possible to obtain a completer picture of ETC activity, its dynamic assembly and disassembly, and how this regulates mitochondrial structure and function. This work will also discuss limitations of these techniques. In summary, the technique of native PAGE, followed by immunoblotting, IGA, and electroelution, presented below, is a powerful way to investigate the functionality and composition of mitochondrial ETC supercomplexes.

This protocol describes the separation of functional mitochondrial electron transport chain complexes (Cx) I-V and supercomplexes thereof using native electrophoresis to reveal information about their assembly and structure. The native gel can be subjected to immunoblotting, in-gel assays, and purification by electroelution to further characterize individual complexes.

The mitochondrial electron transport chain (ETC) transduces the energy derived from the breakdown of various fuels into the bioenergetic currency of the ...

Horizontal Gel Electrophoresis for Enhanced Detection of Protein-RNA Complexes

Native polyacrylamide gel electrophoresis is a fundamental tool of molecular biology that has been used extensively for the biochemical analysis of RNA-protein interactions. These interactions have been traditionally analyzed with polyacrylamide gels generated between two glass plates and samples electrophoresed vertically. However, polyacrylamide gels cast in trays and electrophoresed horizontally offers several advantages. For example, horizontal gels used to analyze complexes between fluorescent RNA substrates and specific proteins can be imaged multiple times as electrophoresis progresses. This provides the unique opportunity to monitor RNA-protein complexes at several points during the experiment. In addition, horizontal gel electrophoresis makes it possible to analyze many samples in parallel. This can greatly facilitate time course experiments as well as analyzing multiple reactions simultaneously to compare different components and conditions. Here we provide a detailed protocol for generating and using horizontal native gel electrophoresis for analyzing RNA-Protein interactions.

Native polyacrylamide gel electrophoresis is a fundamental tool for analyzing RNA-protein interactions. Traditionally most experiments have used vertical gels. However, horizontal gels provide several advantages, such as the opportunity to monitor complexes during electrophoresis. We provide a detailed protocol for generating and using horizontal native gel electrophoresis.

Native polyacrylamide gel electrophoresis is a fundamental tool of molecular biology that has been used extensively for the biochemical analysis of ...

DNA Polymerase Activity Assay Using Near-infrared Fluorescent Labeled DNA Visualized by Acrylamide Gel Electrophoresis

For any enzyme, robust, quantitative methods are required for characterization of both native and engineered enzymes. For DNA polymerases, DNA synthesis can be characterized using an in vitro DNA synthesis assay followed by polyacrylamide gel electrophoresis. The goal of this assay is to quantify synthesis of both natural DNA and modified DNA (M-DNA). These approaches are particularly useful for resolving oligonucleotides with single nucleotide resolution, enabling observation of individual steps during enzymatic oligonucleotide synthesis. These methods have been applied to the evaluation of an array of biochemical and biophysical properties such as the measurement of steady-state rate constants of individual steps of DNA synthesis, the error rate of DNA synthesis, and DNA binding affinity. By using modified components including, but not limited to, modified nucleoside triphosphates (NTP), M-DNA, and/or mutant DNA polymerases, the relative utility of substrate-DNA polymerase pairs can be effectively evaluated. Here, we detail the assay itself, including the changes that must be made to accommodate nontraditional primer DNA labeling strategies such as near-infrared fluorescently labeled DNA. Additionally, we have detailed crucial technical steps for acrylamide gel pouring and running, which can often be technically challenging.

This protocol describes the characterization of DNA polymerase synthesis of modified DNA through observation of changes to near-infrared fluorescently labeled DNA using gel electrophoresis and gel imaging. Acrylamide gels are used for high resolution imaging of the separation of short nucleic acids, which migrate at different rates depending on size.

For any enzyme, robust, quantitative methods are required for characterization of both native and engineered enzymes. For DNA polymerases, DNA synthesis ...

Highly Sensitive and Quantitative Detection of Proteins and Their Isoforms by Capillary Isoelectric Focusing Method

Immunoblotting has become a routine technique in many laboratories for protein characterization from biological samples. The following protocol provides an alternative strategy, capillary isoelectric focusing (cIEF), with many advantages compared to conventional immunoblotting. This is an antibody-based, automated, rapid, and quantitative method in which a complete western blotting procedure takes place inside an ultrathin capillary. This technique does not require a gel to transfer to a membrane, stripping of blots, or x-ray films, which are typically required for conventional immunoblotting. Here, proteins are separated according to their charge (isoelectric point; pI), using less than a microliter (400 nL) of total protein lysate. After electrophoresis, proteins are immobilized onto the capillary walls by ultraviolet light treatment, followed by primary and secondary (horseradish peroxidase (HRP) conjugated) antibody incubation, whose binding is detected through enhanced chemiluminescence (ECL), generating a light signal that can be captured and recorded by a charge-coupled device (CCD) camera. The digital image can be analyzed and quantified (peak area) using software. This high throughput procedure can handle 96 samples at a time; is highly sensitive, with protein detection in the picogram range; and produces highly reproducible results because of automation. All of these aspects are extremely valuable when the quantity of samples (e.g., tissue samples and biopsies) is a limiting factor. The technique has wider applications as well, including screening of drugs or antibodies, biomarker discovery, and diagnostic purposes.

Capillary isoelectric focusing is an antibody-based, ultrasensitive, high throughput technique, enabling detailed characterization of proteins and their isoforms from extremely small biological samples. The following describes a protocol for detection and quantification of specific proteins and their isoforms in an automated and robotized manner.

Immunoblotting has become a routine technique in many laboratories for protein characterization from biological samples. The following protocol provides ...

Use of Two Dimensional Semi-denaturing Detergent Agarose Gel Electrophoresis to Confirm Size Heterogeneity of Amyloid or Amyloid-like Fibers

Amyloid or amyloid-like fibers have been associated with many human diseases, and are now being discovered to be important for many signaling pathways. The ability to readily detect the formation of these fibers under various experimental conditions is essential for understanding their potential function. Many methods have been used to detect the fibers, but not without some drawbacks. For example, electron microscopy (EM), or staining with Congo Red or Thioflavin T often requires purification of the fibers. On the other hand, semi-denaturing detergent agarose gel electrophoresis (SDD-AGE) allows detection of the SDS-resistant amyloid-like fibers in the cell extracts without purification. In addition, it allows the comparison of the size difference of the fibers. More importantly, it can be used to identify specific proteins within the fibers by Western blotting. It is less time consuming and more easily accessible to a wider number of labs. SDD-AGE results often show variable degree of heterogeneity. It raises the question whether part of the heterogeneity results from the dissociation of the protein complex during the electrophoresis in the presence of SDS. For this reason, we have employed a second dimension of SDD-AGE to determine if the size heterogeneity seen in SDD-AGE is truly a result of fiber heterogeneity in vivo and not a result of either degradation or dissociation of some of the proteins during electrophoresis. This method allows fast, qualitative confirmation that the amyloid or amyloid-like fibers are not partially dissociating during the SDD-AGE process.

Here we use two-dimensional semi-denaturing agarose gel electrophoresis to confirm the presence of amyloid-like fibers of heterogeneous size and exclude the possibility that the size heterogeneity is due to dissociation of the amyloid fibers during the gel running process.

Amyloid or amyloid-like fibers have been associated with many human diseases, and are now being discovered to be important for many signaling pathways. ...

Analysis of Thylakoid Membrane Protein Complexes by Blue Native Gel Electrophoresis

Photosynthetic electron transfer chain (ETC) converts solar energy to chemical energy in the form of NADPH and ATP. Four large protein complexes embedded in the thylakoid membrane harvest solar energy to drive electrons from water to NADP+ via two photosystems, and use the created proton gradient for production of ATP. Photosystem PSII, PSI, cytochrome b6f (Cyt b6f) and ATPase are all multiprotein complexes with distinct orientation and dynamics in the thylakoid membrane. Valuable information about the composition and interactions of the protein complexes in the thylakoid membrane can be obtained by solubilizing the complexes from the membrane integrity by mild detergents followed by native gel electrophoretic separation of the complexes. Blue native polyacrylamide gel electrophoresis (BN-PAGE) is an analytical method used for the separation of protein complexes in their native and functional form. The method can be used for protein complex purification for more detailed structural analysis, but it also provides a tool to dissect the dynamic interactions between the protein complexes. The method was developed for the analysis of mitochondrial respiratory protein complexes, but has since been optimized and improved for the dissection of the thylakoid protein complexes. Here, we provide a detailed up-to-date protocol for analysis of labile photosynthetic protein complexes and their interactions in Arabidopsis thaliana.

A protocol for the elucidation of plant thylakoid protein complex organization and composition with blue native polyacrylamide gel electrophoresis (BN-PAGE) and 2D-SDS-PAGE is described. The protocol is optimized for Arabidopsis thaliana, but can be used for other plant species with minor modifications.

Photosynthetic electron transfer chain (ETC) converts solar energy to chemical energy in the form of NADPH and ATP. Four large protein complexes embedded ...

Hybrid Clear/Blue Native Electrophoresis for the Separation and Analysis of Mitochondrial Respiratory Chain Supercomplexes

Complexes of the oxidative phosphorylation machinery form supramolecular protein arrangements named supercomplexes (SCs), which are believed to confer structural and functional advantages to mitochondria. SCs have been identified in many species, from yeast to mammal, and an increasing number of studies report disruption of their organization in genetic and acquired human diseases. As a result, an increasing number of laboratories are interested in analyzing SCs, which can be methodologically challenging. This article presents an optimized protocol that combines the advantages of Blue- and Clear-Native PAGE methods to resolve and analyze SCs in a time-effective manner. With this hybrid CN/BN-PAGE method, mitochondrial SCs extracted with optimal amounts of the mild detergent digitonin are exposed briefly to the anionic dye Coomassie Blue (CB) at the beginning of the electrophoresis, without exposure to other detergents. This short exposure to CB allows to separate and resolve SCs as effectively as with traditional BN-PAGE methods, while avoiding the negative impact of high CB levels on in-gel activity assays, and labile protein-protein interactions within SCs. With this protocol it is thus possible to combine precise and rapid in gel activity measurements with analytical techniques involving 2D electrophoresis, immuno-detection, and/or proteomics for advanced analysis of SCs.

Here we present a protocol to extract, resolve and identify mitochondrial supercomplexes which minimizes exposure to detergents and Coomassie Blue. This protocol offers an optimal balance between resolution, and preservation of enzyme activities, while minimizing the risk of losing labile protein-protein interactions.

Complexes of the oxidative phosphorylation machinery form supramolecular protein arrangements named supercomplexes (SCs), which are believed to confer ...