Name: a semi-high-throughput adaptation of the nadh-coupled atpase assay for screening small molecule inhibitors
Uploaded: 2019-08-17T14:00:00
Description: Watch this Scientific Journal Video about A Semi-High-Throughput Adaptation of the NADH-Coupled ATPase Assay for Screening Small Molecule Inhibitors at JoVE.com

This work was supported by a grant from the National Institute of Neurological Disorders and Stroke and National Institute on Drug Abuse NS096833 (CAM).

1. Preparing stock solutions and reagents
<ol>
	<li>Prepare dithiothreitol (DTT) stock solution by dissolving crystalline DTT in distilled water to a final concentration of 1000 mM. Adjust the pH to 7.0 with 1 M NaOH solution. Aliquot and store at -20 &#176;C.</li>
	<li>Prepare ATP stock solution by dissolving crystalline ATP in distilled water to a final concentration of 100 mM. Adjust the pH to 7.0 with 1 M NaOH solution. Aliquot and store at -20 &#176;C.</li>
	<li>Prepare 10x NADH buffer containing 70 mM 3-(N-morpho...

<ol>
	<li>Heissler, S. M., Sellers, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Kinetic+Adaptations+of+Myosins+for+Their+Diverse+Cellular+Functions.">Kinetic Adaptations of Myosins for Their Diverse Cellular Functions.</a> Traffic. 17 (8), 839-859 (2016).</li><li>Hartman, M. A., Spudich, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+myosin+superfamily+at+a+glance.">The myosin superfamily at a glance.</a> Journal of Cell Science. 125 (Pt 7), 1627-1632 (2012).</li><li>Berg, J. S., Powell, B. C., Cheney, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+millennial+myosin+census.">A millennial myosin census.</a> Molecular Biology of the Cell. 12 (4), 780-794 (2001).</li><li>Sebe-Pedros, A., Grau-Bove, X., Richards, T. A., Ruiz-Trillo, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evolution+and+classification+of+myosins,+a+paneukaryotic+whole-genome+approach.">Evolution and classification of myosins, a paneukaryotic whole-genome approach.</a> Genome Biology and Evolution. 6 (2), 290-305 (2014).</li><li>Newell-Litwa, K. A., Horwitz, R., Lamers, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-muscle+myosin+II+in+disease:+mechanisms+and+therapeutic+opportunities.">Non-muscle myosin II in disease: mechanisms and therapeutic opportunities.</a> Disease Models &amp; Mechanisms. 8 (12), 1495-1515 (2015).</li><li>He, Y. M., Gu, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Research+progress+of+myosin+heavy+chain+genes+in+human+genetic+diseases.">Research progress of myosin heavy chain genes in human genetic diseases.</a> Yi Chuan. 39 (10), 877-887 (2017).</li><li>Rauscher, A. A., Gyimesi, M., Kovacs, M., Malnasi-Csizmadia, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeting+Myosin+by+Blebbistatin+Derivatives:+Optimization+and+Pharmacological+Potential.">Targeting Myosin by Blebbistatin Derivatives: Optimization and Pharmacological Potential.</a> Trends in Biochemical Sciences. 43 (9), 700-713 (2018).</li><li>Straight, A. F., 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=Dissecting+temporal+and+spatial+control+of+cytokinesis+with+a+myosin+II+Inhibitor.">Dissecting temporal and spatial control of cytokinesis with a myosin II Inhibitor.</a> Science. 299 (5613), 1743-1747 (2003).</li><li>Sirigu, 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=Highly+selective+inhibition+of+myosin+motors+provides+the+basis+of+potential+therapeutic+application.">Highly selective inhibition of myosin motors provides the basis of potential therapeutic application.</a> Proceedings of the National Academy of Sciences of the United States of America. 113 (47), E7448-E7455 (2016).</li><li>Green, E. 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=A+small-molecule+inhibitor+of+sarcomere+contractility+suppresses+hypertrophic+cardiomyopathy+in+mice.">A small-molecule inhibitor of sarcomere contractility suppresses hypertrophic cardiomyopathy in mice.</a> Science. 351 (6273), 617-621 (2016).</li><li>Morgan, B. 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=Discovery+of+omecamtiv+mecarbil+the+first,+selective,+small+molecule+activator+of+cardiac+Myosin.">Discovery of omecamtiv mecarbil the first, selective, small molecule activator of cardiac Myosin.</a> ACS Medicinal Chemistry Letters. 1 (9), 472-477 (2010).</li><li>Kepiro, 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=para-Nitroblebbistatin,+the+non-cytotoxic+and+photostable+myosin+II+inhibitor.">para-Nitroblebbistatin, the non-cytotoxic and photostable myosin II inhibitor.</a> Angewandte Chemie International Edition. 53 (31), 8211-8215 (2014).</li><li>Varkuti, B. H., 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+highly+soluble,+non-phototoxic,+non-fluorescent+blebbistatin+derivative.">A highly soluble, non-phototoxic, non-fluorescent blebbistatin derivative.</a> Scientific Reports. 6, 26141 (2016).</li><li>Verhasselt, 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=Discovery+of+(S)-3'-hydroxyblebbistatin+and+(S)-3'-aminoblebbistatin:+polar+myosin+II+inhibitors+with+superior+research+tool+properties.">Discovery of (S)-3'-hydroxyblebbistatin and (S)-3'-aminoblebbistatin: polar myosin II inhibitors with superior research tool properties.</a> Organic and Biomolecular Chemistry. 15 (9), 2104-2118 (2017).</li><li>Verhasselt, S., Roman, B. I., Bracke, M. E., Stevens, C. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+synthesis+and+comparative+analysis+of+the+tool+properties+of+new+and+existing+D-ring+modified+(S)-blebbistatin+analogs.">Improved synthesis and comparative analysis of the tool properties of new and existing D-ring modified (S)-blebbistatin analogs.</a> European Journal of Medicinal Chemistry. 136, 85-103 (2017).</li><li>Warren, G. B., Toon, P. A., Birdsall, N. J., Lee, A. G., Metcalfe, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reconstitution+of+a+calcium+pump+using+defined+membrane+components.">Reconstitution of a calcium pump using defined membrane components.</a> Proceedings of the National Academy of Sciences of the United States of America. 71 (3), 622-626 (1974).</li><li>Kiianitsa, K., Solinger, J. A., Heyer, W. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rad54+protein+exerts+diverse+modes+of+ATPase+activity+on+duplex+DNA+partially+and+fully+covered+with+Rad51+protein.">Rad54 protein exerts diverse modes of ATPase activity on duplex DNA partially and fully covered with Rad51 protein.</a> Journal of Biological Chemistry. 277 (48), 46205-46215 (2002).</li><li>Hanzelmann, P., Schindelin, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+Basis+of+ATP+Hydrolysis+and+Intersubunit+Signaling+in+the+AAA++ATPase+p97.">Structural Basis of ATP Hydrolysis and Intersubunit Signaling in the AAA+ ATPase p97.</a> Structure. 24 (1), 127-139 (2016).</li><li>Hackney, D. D., Jiang, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assays+for+kinesin+microtubule-stimulated+ATPase+activity.">Assays for kinesin microtubule-stimulated ATPase activity.</a> Methods in Molecular Biology. 164, 65-71 (2001).</li><li>Kiianitsa, K., Solinger, J. A., Heyer, W. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=NADH-coupled+microplate+photometric+assay+for+kinetic+studies+of+ATP-hydrolyzing+enzymes+with+low+and+high+specific+activities.">NADH-coupled microplate photometric assay for kinetic studies of ATP-hydrolyzing enzymes with low and high specific activities.</a> Analytical Biochemistry. 321 (2), 266-271 (2003).</li><li>Carter, S. G., Karl, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inorganic+phosphate+assay+with+malachite+green:+an+improvement+and+evaluation.">Inorganic phosphate assay with malachite green: an improvement and evaluation.</a> Journal of Biochemical and Biophysical Methods. 7 (1), 7-13 (1982).</li><li>Henkel, R. D., VandeBerg, J. L., Walsh, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+microassay+for+ATPase.">A microassay for ATPase.</a> Analytical Biochemistry. 169 (2), 312-318 (1988).</li><li>Rowlands, M. G., 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=High-throughput+screening+assay+for+inhibitors+of+heat-shock+protein+90+ATPase+activity.">High-throughput screening assay for inhibitors of heat-shock protein 90 ATPase activity.</a> Analytical Biochemistry. 327 (2), 176-183 (2004).</li><li>Rule, C. S., Patrick, M., Sandkvist, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+In+Vitro+ATPase+Activity+for+Enzymatic+Characterization.">Measuring In Vitro ATPase Activity for Enzymatic Characterization.</a> Journal of Visualized Experiments. (114), 54305 (2016).</li><li>Pardee, J. D., Spudich, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+of+muscle+actin.">Purification of muscle actin.</a> Methods in Cell Biology. 24, 271-289 (1982).</li><li>Zhang, J. H., Chung, T. D., Oldenburg, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Simple+Statistical+Parameter+for+Use+in+Evaluation+and+Validation+of+High+Throughput+Screening+Assays.">A Simple Statistical Parameter for Use in Evaluation and Validation of High Throughput Screening Assays.</a> Journal of Biomolecular Screening. 4 (2), 67-73 (1999).</li><li>Kovacs, M., Toth, J., Hetenyi, C., Malnasi-Csizmadia, A., Sellers, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanism+of+blebbistatin+inhibition+of+myosin+II.">Mechanism of blebbistatin inhibition of myosin II.</a> Chem Journal of Biological Chemistry. 279 (34), 35557-35563 (2004).</li><li>Allingham, J. S., Smith, R., Rayment, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+structural+basis+of+blebbistatin+inhibition+and+specificity+for+myosin+II.">The structural basis of blebbistatin inhibition and specificity for myosin II.</a> Nature Structural &amp; Molecular Biology. 12 (4), 378-379 (2005).</li><li>Kettlun, A. 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=Purification+and+Characterization+of+2+Isoapyrases+from+Solanum-Tuberosum+Var+Ultimus.">Purification and Characterization of 2 Isoapyrases from Solanum-Tuberosum Var Ultimus.</a> Phytochemistry. 31 (11), 3691-3696 (1992).</li><li>Hulme, E. C., Trevethick, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ligand+binding+assays+at+equilibrium:+validation+and+interpretation.">Ligand binding assays at equilibrium: validation and interpretation.</a> British Journal of Pharmacology. 161 (6), 1219-1237 (2010).</li><li>Motulsky, H. J., Neubig, R. 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Critical steps in the protocol
Optimize plate layout by running several plates with negative control only (ATPase reaction with no inhibitor). Inspect the results carefully for patterns in reaction rates. For example, these may arise from edge effects and/or imperfections in the hydrophilic surface coating of &#34;non-binding&#34; plates. If a pattern is observed, change plate type and/or plate layout to minimize the artifacts. For example, a typical dose-response curve (16 co...

Myosins are mechanochemical energy transducers that hydrolyze adenosine triphosphate (ATP) to generate directional movement along the filaments of the actin cytoskeleton in eukaryotes1,2. They have both structurally and kinetically adapted to their various intracellular functions, such as the transport of organelles, muscle contraction or the generation of cytoskeletal tension1,2. The myosin superfamily is represented by ~40 myosin genes belonging to ~12 distinct myosin classes in the human genome3,4. Members of the myosin classes play various roles in a highly diverse set of disorders, such as several cancers, neurological disorders, skeletal myopathies, and hypertrophic cardiomyopathy5,6. Given the large number of physiological and pathological functions of these molecular motors, it is not surprising that they are becoming increasingly recognized as drug targets for a variety of conditions7. Significant progress has been made recently in the discovery of new myosin inhibitors8,9,10 and activators11, and to improve the properties of existing ones12,13,14,15.
The nicotinamide adenine dinucleotide (NADH)-coupled ATPase assay has long been used to measure the ATPase activity of various enzymes, such as the sarcoplasmic reticulum Ca2+ pump ATPase16, the DNA repair ATPase Rad5417, the AAA+ ATPase p9718 or the microtubule motor kinesin19. The assay employs an ATP regeneration cycle. The adenosine diphosphate (ADP) generated by the ATPase is regenerated to ATP by pyruvate kinase (PK), which transforms one molecule of phosphoenolpyruvate (PEP) to pyruvate in parallel. Subsequently, pyruvate is reduced to lactate by lactate dehydrogenase (LDH). That, in turn, oxidizes one molecule of NADH to NAD. Therefore, the decrease in NADH concentration as a function of time equals the ATP hydrolysis rate. The ATP regeneration cycle keeps the ATP concentration nearly constant and the ADP concentration low as long as PEP is available. This results in linear time courses, making it simple to determine the initial reaction rates and helps to avoid product inhibition by ADP19. Although the NADH-coupled ATPase assay has already been adapted to a 96-well format20, the high reaction volumes (~150 &#181;L) make it relatively expensive due to the high demand of reagents, rendering it less amenable to rapid screening of large numbers of compounds. Alternative methods, such as the malachite green assay19,21, which relies on the detection of the phosphate produced by the ATPase enzyme, were proven more suitable for miniaturization and high-throughput screening22,23,24. However, an endpoint assay is more likely to be affected by several artifacts (discussed below), which may remain undiscovered in the absence of full-time courses.
Here, the NADH-coupled ATPase assay has been optimized for semi-high throughput screening of small molecule inhibitors. Skeletal and cardiac muscle myosin II&#39;s and the myosin inhibitors blebbistatin8, para-aminoblebbistatin13 and para-nitroblebbistatin12 are used to demonstrate the power of the assay, which relies on NADH fluorescence as a readout. This protocol is amenable to screening projects focused on any ADP producing enzymes.

<table border="0" cellpadding="0" cellspacing="0" style="width:956px;" width="955">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:515px;">384-well Low Flange Black Flat Bottom Polystyrene NBS Microplate</td>
			<td style="width:147px;">Corning</td>
			<td style="width:123px;">3575</td>
			<td style="width:172px;"></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">ATP (Adenosine 5&#8242;-triphosphate disodium salt hydrate)</td>
			<td>Sigma</td>
			<td>A7699</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">Aurora FRD-IB Dispenser</td>
			<td>Aurora Discovery, Inc.</td>
			<td>00017425</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">Biomek NXP Multichannel Laboratory Automation Workstation</td>
			<td>Beckman Coulter</td>
			<td>A31841</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Blebbistatin</td>
			<td style="width:147px;">AMRI</td>
			<td style="width:123px;">N/A</td>
			<td>Custom synthesis</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BSA (Bovine Serum Albumin, Protease-Free)</td>
			<td>Akron Biotech</td>
			<td>AK1391&#160;</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">Centrifuge 5430 R, refrigerated, with Rotor FA-35-6-30</td>
			<td>Eppendorf</td>
			<td>022620663</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">Centrifuge 5430, non-refrigerated, with Rotor A-2-MTP</td>
			<td>Eppendorf</td>
			<td>022620568</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DMSO (Dimethyl sulfoxide)</td>
			<td>&#160;Sigma</td>
			<td>D2650</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">DTT (DL-Dithiothreitol)</td>
			<td>&#160;Sigma</td>
			<td>D5545</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">E1 ClipTip Multichannel Pipette; 384-format; 8-channel</td>
			<td>Thermo Scientific</td>
			<td>4672010</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">E1 ClipTip Multichannel Pipette; 96-format; 8-channel</td>
			<td>Thermo Scientific</td>
			<td>4672080</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">EGTA (Ethylene glycol-bis(2-aminoethylether)-N,N,N&#8242;,N&#8242;-tetraacetic acid)</td>
			<td>&#160;Sigma</td>
			<td>E3889</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">EnVision 2104 Multilabel Plate Reader</td>
			<td>PerkinElmer</td>
			<td>2104-0010</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">Glycerol</td>
			<td>&#160;Sigma</td>
			<td>G2025</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">LDH (L-Lactic Dehydrogenase from rabbit muscle)</td>
			<td>Sigma</td>
			<td>L1254</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MgCl2.6H2O (Magnesium chloride hexahydrate)</td>
			<td>&#160;Sigma</td>
			<td>M2670</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">Microplate Shaker</td>
			<td>VWR</td>
			<td>&#160; 12620-926&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microplate, 384 well, PP, Small Volume, Deep Well, Natural</td>
			<td>Greiner Bio-One</td>
			<td>784201</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">MOPS (3-(N-Morpholino)propanesulfonic acid)</td>
			<td>&#160;Sigma</td>
			<td>M1254</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">Myosin Motor Protein (full length) (Bovine cardiac muscle)</td>
			<td>Cytoskeleton&#160;</td>
			<td>MY03</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">Myosin Motor Protein (full length) (Rabbit skeletal muscle)</td>
			<td>Cytoskeleton&#160;</td>
			<td>MY02</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">NADH (&#946;-Nicotinamide adenine dinucleotide, reduced disodium salt hydrate)</td>
			<td>Sigma</td>
			<td>N8129</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NaN3 (Sodium azide)</td>
			<td>&#160;Sigma</td>
			<td>71289</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">NaOH (Sodium hydroxide)</td>
			<td>&#160;Sigma</td>
			<td>S8045</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">Optical Filter CFP 470/24nm (Emission)</td>
			<td>PerkinElmer</td>
			<td>2100-5850</td>
			<td>Barcode 240</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">Optical Filter Fura2 380/10nm (Excitation)</td>
			<td>PerkinElmer</td>
			<td>2100-5390</td>
			<td>Barcode 112</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">Optical Module: Beta Lactamase</td>
			<td>PerkinElmer</td>
			<td>2100-4270</td>
			<td>Barcode 418</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">OriginPro 2017 software</td>
			<td>OriginLab</td>
			<td style="width:123px;">N/A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">para-Aminoblebbistatin</td>
			<td style="width:147px;">AMRI</td>
			<td style="width:123px;">N/A</td>
			<td>Custom synthesis</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">para-Nitroblebbistatin</td>
			<td style="width:147px;">AMRI</td>
			<td style="width:123px;">N/A</td>
			<td>Custom synthesis</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">PEP (Phospho(enol)pyruvic acid monopotassium salt)</td>
			<td>Sigma</td>
			<td>P7127</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">PK (Pyruvate Kinase from rabbit muscle)</td>
			<td>Sigma</td>
			<td>P9136</td>
			<td></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:20px;">Rabbit Muscle Acetone Powder</td>
			<td>Pel Freez Biologicals</td>
			<td>41995-2</td>
			<td></td>
		</tr>
	</tbody>
</table>

a semi-high-throughput adaptation of the nadh-coupled atpase assay for screening small molecule inhibitors

ATPase enzymes utilize the free energy stored in adenosine triphosphate to catalyze a wide variety of endergonic biochemical processes in vivo that would not occur spontaneously. These proteins are crucial for essentially all aspects of cellular life, including metabolism, cell division, responses to environmental changes and movement. The protocol presented here describes a nicotinamide adenine dinucleotide (NADH)-coupled ATPase assay that has been adapted to semi-high throughput screening of small molecule ATPase inhibitors. The assay has been applied to cardiac and skeletal muscle myosin II's, two actin-based molecular motor ATPases, as a proof of principle. The hydrolysis of ATP is coupled to the oxidation of NADH by enzymatic reactions in the assay. First, the ADP generated by the ATPase is regenerated to ATP by pyruvate kinase (PK). PK catalyzes the transition of phosphoenolpyruvate (PEP) to pyruvate in parallel. Subsequently, pyruvate is reduced to lactate by lactate dehydrogenase (LDH), which catalyzes the oxidation of NADH in parallel. Thus, the decrease in ATP concentration is directly correlated to the decrease in NADH concentration, which is followed by change to the intrinsic fluorescence of NADH. As long as PEP is available in the reaction system, the ADP concentration remains very low, avoiding inhibition of the ATPase enzyme by its own product. Moreover, the ATP concentration remains nearly constant, yielding linear time courses. The fluorescence is monitored continuously, which allows for easy estimation of the quality of data and helps to filter out potential artifacts (e.g., arising from compound precipitation or thermal changes).

The typical plate layout map used for screening experiments is shown in Figure 1. The first and last rows are reserved for NADH calibration and positive control (20 &#181;M para-aminoblebbistatin, 0.5% DMSO), respectively. The remaining rows (B to O) are used to test the inhibitory activity of compounds. Here, fifteen-step serial 1:2 dilutions starting from 10 mM compound concentration in DMSO are prepared and transferred from the compound plate to t...

Watch this Scientific Journal Video about A Semi-High-Throughput Adaptation of the NADH-Coupled ATPase Assay for Screening Small Molecule Inhibitors at JoVE.com

A Semi-High-Throughput Adaptation of the NADH-Coupled ATPase Assay for Screening Small Molecule Inhibitors

A nicotinamide adenine dinucleotide (NADH)-coupled ATPase assay has been adapted to semihigh throughput screening of small molecule myosin inhibitors. This kinetic assay is run in a 384-well microplate format with total reaction volumes of only 20 &#181;L per well. The platform should be applicable to virtually any ADP producing enzyme.

ATPase enzymes utilize the free energy stored in adenosine triphosphate to catalyze a wide variety of endergonic biochemical processes in vivo that would ...

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