Name: preparation and in vivo use of an activity-based probe for n-acylethanolamine acid amidase
Uploaded: 2016-11-23T13:00:00
Description: Watch this Scientific Journal Video about Preparation and In Vivo Use of an Activity-based Probe for N-acylethanolamine Acid Amidase at JoVE.com

The authors thank the Nikon Imaging Center at Istituto Italiano di Tecnologia, Genova, Italy (NIC@IIT).

Caution: All chemistry reactions should be carried out in a ventilated fume hood and with the use of a lab coat, gloves, and protective goggles. The reactions should be also carried out in a nitrogen environment.
Ethical statement: Our procedures involving animals are performed in accordance with the Italian regulations on the protection of animals used for experimental and other scientific purposes (D.M. 116192), and European Economic Community regulations (O.J. of E.C. L 358/1 12/18/1986).
NOTE: Synthesis of [(3S)-2-...

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Y., Tsuboi, K., Okamoto, Y., Nagahata, S., Ueda, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proteolytic+activation+and+glycosylation+of+N-acylethanolamine-hydrolyzing+acid+amidase,+a+lysosomal+enzyme+involved+in+the+endocannabinoid+metabolism.">Proteolytic activation and glycosylation of N-acylethanolamine-hydrolyzing acid amidase, a lysosomal enzyme involved in the endocannabinoid metabolism.</a> Biochim Biophys Acta. 1771, 1397-1405 (2007).</li><li>Wang, 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=Amino+acid+residues+crucial+in+pH+regulation+and+proteolytic+activation+of+N-acylethanolamine-hydrolyzing+acid+amidase.">Amino acid residues crucial in pH regulation and proteolytic activation of N-acylethanolamine-hydrolyzing acid amidase.</a> Biochim Biophys Acta. 1781, 710-717 (2008).</li><li>West, J. 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T., Makriyannis, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mass+spectrometric+characterization+of+human+N-acylethanolamine-hydrolyzing+acid+amidase.">Mass spectrometric characterization of human N-acylethanolamine-hydrolyzing acid amidase.</a> J Proteome Res. 11, 972-981 (2012).</li><li>Bandiera, T., Ponzano, S., Piomelli, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advances+in+the+discovery+of+N-acylethanolamine+acid+amidase+inhibitors.">Advances in the discovery of N-acylethanolamine acid amidase inhibitors.</a> Pharmacol Res. 86, 11-17 (2014).</li><li>Sasso, O., 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=Antinociceptive+effects+of+the+N-acylethanolamine+acid+amidase+inhibitor+ARN077+in+rodent+pain+models.">Antinociceptive effects of the N-acylethanolamine acid amidase inhibitor ARN077 in rodent pain models.</a> Pain. 154, 350-360 (2013).</li><li>Duranti, 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=N-(2-oxo-3-oxetanyl)carbamic+acid+esters+as+N-acylethanolamine+acid+amidase+inhibitors:+synthesis+and+structure-activity+and+structure-property+relationships.">N-(2-oxo-3-oxetanyl)carbamic acid esters as N-acylethanolamine acid amidase inhibitors: synthesis and structure-activity and structure-property relationships.</a> J Med Chem. 55, 4824-4836 (2012).</li><li>Ponzano, 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=Synthesis+and+structure-activity+relationship+(SAR)+of+2-methyl-4-oxo-3-oxetanylcarbamic+acid+esters,+a+class+of+potent+N-acylethanolamine+acid+amidase+(NAAA)+inhibitors.">Synthesis and structure-activity relationship (SAR) of 2-methyl-4-oxo-3-oxetanylcarbamic acid esters, a class of potent N-acylethanolamine acid amidase (NAAA) inhibitors.</a> J Med Chem. 56, 6917-6934 (2013).</li><li>Solorzano, 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=Synthesis+and+structure-activity+relationships+of+N-(2-oxo-3-oxetanyl)amides+as+N-acylethanolamine-hydrolyzing+acid+amidase+inhibitors.">Synthesis and structure-activity relationships of N-(2-oxo-3-oxetanyl)amides as N-acylethanolamine-hydrolyzing acid amidase inhibitors.</a> J Med Chem. 53, 5770-5781 (2010).</li><li>Vitale, R., 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=Synthesis,+structure-activity,+and+structure-stability+relationships+of+2-substituted-N-(4-oxo-3-oxetanyl)+N-acylethanolamine+acid+amidase+(NAAA)+inhibitors.">Synthesis, structure-activity, and structure-stability relationships of 2-substituted-N-(4-oxo-3-oxetanyl) N-acylethanolamine acid amidase (NAAA) inhibitors.</a> ChemMedChem 9. 9, 323-336 (2014).</li><li>Fiasella, 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=3-Aminoazetidin-2-one+derivatives+as+N-acylethanolamine+acid+amidase+(NAAA)+inhibitors+suitable+for+systemic+administration.">3-Aminoazetidin-2-one derivatives as N-acylethanolamine acid amidase (NAAA) inhibitors suitable for systemic administration.</a> ChemMedChem 9. 9, 1602-1614 (2014).</li><li>Armirotti, 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=beta-Lactones+Inhibit+N-acylethanolamine+Acid+Amidase+by+S-Acylation+of+the+Catalytic+N-Terminal+Cysteine.">beta-Lactones Inhibit N-acylethanolamine Acid Amidase by S-Acylation of the Catalytic N-Terminal Cysteine.</a> ACS Med Chem Lett. 3, 422-426 (2012).</li><li>Nuzzi, 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=Potent+alpha-amino-beta-lactam+carbamic+acid+ester+as+NAAA+inhibitors.+Synthesis+and+structure-activity+relationship+(SAR)+studies.">Potent alpha-amino-beta-lactam carbamic acid ester as NAAA inhibitors. 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Enzyme activity is finely regulated at different levels, including RNA transcription, protein synthesis, protein translocation, post-translational modification, and protein-protein interaction. Often, enzyme expression alone does not account for its activity. ABPP was developed to study the activity of proteins in their native state. Two features are required: a chemical probe that covalently binds to the active site of an enzyme of interest and a reporter tag to detect the probe-labeled enzyme.
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Commonly used methods to investigate the expression patterns, interactions, and functions of proteins, including liquid chromatography-mass spectrometry platforms for shotgun analysis1,2, yeast two-hybrid methods3,4, and in vitro assays, are limited in that they are unable to assess the activity of proteins in their native state. Activity-based protein profiling (ABPP) can be used to fill this gap. In this approach, small-molecule probes capable of covalently binding to the active site of an enzyme of interest are conjugated to a reporter group that allows for target detection. Using click chemistry (CC), the reporter can be integrated into the probe or can be introduced after target engagement has occurred5,6. The latter procedure requires the use of probes containing appropriate chemical groups, such as a terminal alkyne or azide, which can be modified with a number of reporter reagents via bio-orthogonal reactions such as the Cu(I)-catalyzed Huisgen [3+2] cycloaddition7-9 or Staudinger ligation10,11.
Recently, we disclosed the compound ARN14686 as the first ABP for the in vitro and in vivo detection of the cysteine hydrolase, NAAA12. NAAA catalyzes the hydrolytic deactivation of saturated and monounsaturated FAEs, including oleoylethanolamide (OEA) and palmitoylethanolamide (PEA), which are endogenous agonists of the anti-inflammatory nuclear receptor PPAR-alpha13-15. NAAA is predominantly expressed in macrophages and other monocyte-derived cells, as well as in B-lymphocytes14,16, suggesting a role in the regulation of the innate immune response. The enzyme is synthesized in the rough endoplasmic reticulum in an inactive form and is activated in acidic compartments of the cell by an autoproteolytic mechanism17. The autoproteolytic cleavage generates a new N-terminal cysteine (C131 in mice and rats, C126 in humans), that is the nucleophile responsible for FAE hydrolysis18,19. Pharmacological inhibition of NAAA activity alters the FAE synthesis/degradation balance in favor of increased cellular levels of FAEs16,20,21. Several &#946;-lactone and &#946;-lactam derivatives have been shown to inhibit NAAA activity with high potency and selectivity16,22-26. These inhibitors act through S-acylation of the catalytic cysteine16,27,28.
The compound ARN14686 was designed based on the chemical structure of the systemically active, serine-derived &#946;-lactam NAAA inhibitor, ARN726 (4-cyclohexylbutyl-N-[(S)-2-oxoazetidin-3-yl]carbamate)16. The 4-butyl-cyclohexyl group of ARN726 was replaced with a C9 saturated aliphatic chain bearing a terminal alkyne tag for subsequent CC conjugation with an azide-bearing reporter tag. We chose to design a two-step ABP to minimally alter the structure of the original scaffold, thus maintaining the affinity of the probe for NAAA. Moreover, avoiding the introduction of bulky tags, such a probe could be more suitable for in vivo treatment than a direct ABP. ARN14686 inhibits NAAA with high potency (hNAAA IC50 = 6 nM, rNAAA IC50 = 13 nM) by forming a covalent adduct with the catalytic cysteine of the enzyme12. Experiments in live rats showed that the probe is selective in capturing NAAA expressed in lungs. Acid ceramidase, another cysteine amidase that shares 33-34% identity with NAAA, was also identified as a low-affinity target when using high probe concentrations (10 &#181;M in vitro, 10 mg/ml intravenous, i.v.)12. We have also used ARN14686 to study the presence of active NAAA in inflamed rat tissues following administration of complete Freund&#39;s adjuvant (CFA)29.
Here, we outline a protocol for the preparation of ARN14686 (Figure 1) and its application to the investigation of NAAA activation ex vivo. As an example, we describe an experimental procedure to visualize NAAA in rat paws after CFA administration. In this experiment, proteins are extracted from paw tissue after i.v. injection of the probe, and the ABP-labeled proteome is subjected to CC with biotin-azide. Biotinylated samples are enriched using streptavidin beads, and protein blots are performed. In another application, we describe the localization of active NAAA by fluorescence microscopy in mouse lungs from probe-treated mice. In this case, the tissue is sectioned and sections are subjected to CC for rhodamine addition. A workflow scheme is illustrated in Figure 2.

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		<col />
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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">1,1&#8217;-sulfonyldiimidazole&#160;</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">367818</td>
			<td style="width:471px;">Harmful</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">2-dipyridylcarbonate</td>
			<td style="width:205px;">Fluorochem</td>
			<td style="width:111px;">11331</td>
			<td style="width:471px;">Harmful</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">2-Methylbutan</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">M32631</td>
			<td>Flamable, toxic,hazardous to the aquatic environment</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">4-(Dimethylamino)pyridine</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">107700</td>
			<td style="width:471px;">Toxic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Acetic acid</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">695092</td>
			<td style="width:471px;">Flammable, Corrosive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Acetonitrile&#160;</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">34998</td>
			<td style="width:471px;">Flammable, Toxic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Activated charcoal</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">161551</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Ammonium chloride</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">A9434</td>
			<td style="width:471px;">Harmful</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Azide-PEG3-Biotin</td>
			<td style="width:205px;">Jena Biosciences</td>
			<td style="width:111px;">CLK-AZ104P4</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Azide-PEG3-Fluor 545</td>
			<td style="width:205px;">Jena Biosciences</td>
			<td style="width:111px;">CLK-AZ109</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">BCA protein assay kit</td>
			<td style="width:205px;">Thermo Fisher Scientific</td>
			<td style="width:111px;">23227</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Bio-spin columns</td>
			<td style="width:205px;">Biorad</td>
			<td style="width:111px;">732-6204</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Biotin</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">B4501</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Blocking buffer</td>
			<td style="width:205px;">Li-Cor Biosciences</td>
			<td style="width:111px;">927-40000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">b-mercaptoethanol</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">M6250</td>
			<td>Higly toxic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Bovin serum albumine (BSA)</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">A7030</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Bromophenol blue</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">B0126</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Bruker Avance III 400</td>
			<td style="width:205px;">Bruker</td>
			<td style="width:111px;"></td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Celite</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">419931</td>
			<td style="width:471px;">Health hazard</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Ceric ammonium nitrate&#160;</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">22249</td>
			<td style="width:471px;">Oxidizing, Harmful</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Chloral hydrate</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">C8383</td>
			<td>Higly toxic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">CuSO4.5H2O&#160;</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">209198</td>
			<td>Toxic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Cyclohexadiene</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">125415</td>
			<td style="width:471px;">Flammable, Health hazard</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Cyclohexane</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">34855</td>
			<td style="width:471px;">Flammable, Harmful, Health hazard, Environmental hazard</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Dichloromethane</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">34856</td>
			<td style="width:471px;">Harmful, Health hazard</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Diethyl ether</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">296082</td>
			<td style="width:471px;">Flammable, Harmful</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Dimethyl sulfoxide (DMSO)</td>
			<td style="width:205px;">Acros Organics</td>
			<td style="width:111px;">348441000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Dimethyl sulfoxide d6 (DMSO-d6)</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">175943</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Ethanol</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">2860</td>
			<td style="width:471px;">Flammable, Harmful</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Ethyl acetate</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">34858</td>
			<td style="width:471px;">Flammable, Harmful</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Glycerol</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">G5516</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Irdye 680-LT Streptavidin</td>
			<td style="width:205px;">Li-Cor Biosciences</td>
			<td style="width:111px;">925-68031</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">IRDye680-LT Streptavidin&#160;</td>
			<td style="width:205px;">Licor</td>
			<td style="width:111px;">925-68031</td>
			<td>Briefly centrifuge before use to precipitate protein complexes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Methanol</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">34966</td>
			<td>Highly toxic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Methanol</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">34860</td>
			<td style="width:471px;">Flammable, Toxic, Health hazard</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:423px;">N-(3-Dimethylaminopropyl)-N&#8242;-ethylcarbodiimide hydrochloride</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">E7750</td>
			<td style="width:471px;">Harmful, Corrosive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">N,N-diisopropylethylamine</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">D125806</td>
			<td style="width:471px;">Flammable, Corrosive, Toxic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">N,N-dimethylformamide</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">227056</td>
			<td style="width:471px;">Flammable, Harmful, Health hazard</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">N-Cbz-L-Serine</td>
			<td style="width:205px;">Fluorochem&#160;</td>
			<td style="width:111px;">M03053</td>
			<td style="width:471px;">Harmful</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Nikon A1 confocal microscopy</td>
			<td style="width:205px;">Nikon</td>
			<td style="width:111px;"></td>
			<td>Read&#160; the user manual</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">NuPAGE 4-12% Bis-Tris gel</td>
			<td style="width:205px;">Thermo Fisher Scientific</td>
			<td style="width:111px;">NP0335BOX</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Palladium on carbon</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">330108</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">p-anisidine</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">A88255</td>
			<td style="width:471px;">Toxic, Health hazard, Environmental hazard</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Paraformaldehyde</td>
			<td style="width:205px;">sigma Aldrich</td>
			<td style="width:111px;">441244</td>
			<td>Toxic, respiratory harmful, corrosive, falmable</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Poly(ethylene glycol)&#160;</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">P3265</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">ProLong Gold antifade mountant with DAPI&#160;</td>
			<td style="width:205px;">Thermo Fisher Scientific</td>
			<td style="width:111px;">P36931</td>
			<td>Avoid bubbles formation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Protease inhibitor cocktail</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">P8340</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Sodium bicarbonate</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">S6014</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Sodium dodecyl sulfate (SDS)&#160;</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">L3771</td>
			<td>Toxic, corrosive, falmmable</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Sodium hydride&#160;</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">452912</td>
			<td style="width:471px;">Flammable</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Sodium sulfate</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">239313</td>
			<td style="width:471px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Starion FLA-9000 immage scanner</td>
			<td style="width:205px;">FUJIFILM</td>
			<td style="width:111px;"></td>
			<td>Read&#160; the user manual</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Streptavidin agarose</td>
			<td style="width:205px;">Thermo Fisher Scientific</td>
			<td>20349</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Sucrose</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">S7903</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Tert-butanol</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">360538</td>
			<td>Toxic, flammable</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Tetrahydrofuran</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">186562</td>
			<td style="width:471px;">Flammable, Harmful, Health hazard</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Thiourea</td>
			<td style="width:205px;">Acros Organics</td>
			<td style="width:111px;">424542500</td>
			<td>Toxic, warm at 50 &#176;C to dissolve</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Tris</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">RDD008</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tris(2-carboxyethyl)phosphine (TCEP)</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">C4706</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tris[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]amine (TBTA)</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">678937</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Triton-x100</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">X100</td>
			<td>Toxic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Tween-20</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">P9416</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Tween-80</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">P1754</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Ultra turrax IKA T18 basic tissue homogenizer</td>
			<td style="width:205px;">IKA</td>
			<td style="width:111px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Undec-10-yn-1-ol</td>
			<td style="width:205px;">Fluorochem</td>
			<td style="width:111px;">13739</td>
			<td style="width:471px;">Harmful</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:423px;">Urea</td>
			<td style="width:205px;">Sigma Aldrich</td>
			<td style="width:111px;">U5378</td>
			<td>Toxic, warm at 50 &#176;C to dissolve</td>
		</tr>
	</tbody>
</table>

preparation and in vivo use of an activity-based probe for n-acylethanolamine acid amidase

Activity-based protein profiling (ABPP) is a method for the identification of an enzyme of interest in a complex proteome through the use of a chemical probe that targets the enzyme&#39;s active sites. A reporter tag introduced into the probe allows for the detection of the labeled enzyme by in-gel fluorescence scanning, protein blot, fluorescence microscopy, or liquid chromatography-mass spectrometry. Here, we describe the preparation and use of the compound ARN14686, a click chemistry activity-based probe (CC-ABP) that selectively recognizes the enzyme N-acylethanolamine acid amidase (NAAA). NAAA is a cysteine hydrolase that promotes inflammation by deactivating endogenous peroxisome proliferator-activated receptor (PPAR)-alpha agonists such as palmitoylethanolamide (PEA) and oleoylethanolamide (OEA). NAAA is synthesized as an inactive full-length proenzyme, which is activated by autoproteolysis in the acidic pH of the lysosome. Localization studies have shown that NAAA is predominantly expressed in macrophages and other monocyte-derived cells, as well as in B-lymphocytes. We provide examples of how ARN14686 can be used to detect and quantify active NAAA ex vivo in rodent tissues by protein blot and fluorescence microscopy.

ARN14686 was designed based on the scaffold of the NAAA inhibitor ARN726. The 4-butyl-cyclohexyl group of ARN726 was substituted with a C9 saturated aliphatic chain bearing a terminal alkyne tag (Figure 1). The alkyne tag was introduced in order to allow the use of a two-step labeling procedure to add a fluorophore or a biotin molecule via CC. This feature renders ARN14686 a very versatile tool to probe NAAA in vitro and in vivo.
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Watch this Scientific Journal Video about Preparation and In Vivo Use of an Activity-based Probe for N-acylethanolamine Acid Amidase at JoVE.com

Preparation and In Vivo Use of an Activity-based Probe for N-acylethanolamine Acid Amidase

Here, we describe the preparation and use of an activity-based probe (ARN14686, undec-10-ynyl-N-[(3S)-2-oxoazetidin-3-yl]carbamate) that allows for the detection and quantification of the active form of the proinflammatory enzyme N-acylethanolamine acid amidase (NAAA), both in vitro and ex vivo.

Preparation and In Vivo Use of an Activity-based Probe for N-acylethanolamine Acid Amidase

Activity-based protein profiling (ABPP) is a method for the identification of an enzyme of interest in a complex proteome through the use of a chemical ...

The overall goal of this procedure is to show the synthesis of activity based probe, ARN 14 six eight six specific for N-acylethanolamine acid amidase, or NAAA, and describe its use for detecting the catalytically active enzyme in cell extracts and tissue sections. This method can help answer questions about the in viva function of NAAA providing insights into NAAA activation in different physiological and pathological conditions such as inflammatory and neuro degenerative diseases. It's main advantage is that a simple manipulation is subsequent to NAAA reaction with a probe thus giving reliable information about the in viva activation state of the enzyme.Another advantage is that contrary to specific antibodies our probe detects only the active form of the enzyme which is useful for fluorescence microscopy status. Visual demonstration of this method is critical as it combines different expertise that built up to a complete story from proper synthesis to its final applications. In a 50 milliliter round bottom flask dissolve 350 milligrams of undecynenol and three point five milliliters of dry dichloromethane.Then add 25 milligrams of DMAP and 530 milligrams of DPC to this solution. Stir the mixture at room temperature for 16 hours. After 16 hours add 20 milliliters of dichloromethane to the solution.Transfer the mixture into a separating funnel. Add 15 milliliters of water. Shake the mixture and allow the two phases to separate.Next open the stopcock, collect the organic phase on the bottom close the stopcock and transfer the organic phase back to the funnel. Add 15 milliliters of a saturated sodium bicarbonate solution to the mixture. Shake the separating funnel and let the two phases separate.After drying the organic layer with sodium sulfate filter it through cotton into a tiered round bottom flask. Then evaporate the organic layer to dryness under reduced pressure using a rotary evaporator. Weigh the flask and obtain 600 milligrams of oil which is a mixture of two pyridyl undecynyl carbonate and undecynol two oxypyridine carboxylate in a ratio of one point seven to one.In a 10 milliliter round bottom flask dissolve 60 milligrams of oxo asetydenol ammonium asetate in two milliliters of dry dichloromethane. Cool the solution to zero degrees celsius in an ice bath then add 81 microliters of diazapropalethylamine drop wise. Next dissolve 350 milligrams of the crude mixture containing undecynol two oxypyridine carboxylate in two milliliters of dry dichloromethane.Add the dissolved mixture to the solution and stir at room temperature for 15 hours. Then evaporate the solvent to dryness under reduced pressure using a rotary evaporator. Purify the compound by silica gel column chromatography using an automated column chromatography apparatus.First absorb the sample onto silica gel. After equilibriating the column with cyclohexene load the sample into the cartridge. Elute the sample with ethyl acetate in cyclohexane from zero to 100, collecting the peaks into test tubes.Evaporate the solvent of the fractions corresponding to the compound to dryness under reduced pressure using a rotary evaporator to obtain 40 milligrams of a white solid. After pre clearing the sample as described in the text protocol add 11 point three microliters of a five millimolar stock of azide polyethylene glyco biotin and vortex. Then add 11 point three microliters of a 50 millimolar stock of freshly prepared TCEP to the sample and vortex.After premixing 34 microliters of a freshly prepared working solution of one point seven millimolar TBTA with 11 point three microliters of a 50 millimolar copper sulfate stock add 45 point three milliliters of this solution to the sample and vortex. Use labeled containers. Incubate the reaction at 25 degrees Celsius for at least two hours.After one hour incubation observe protein precipitation and mix the reaction. Centrifuge the sample for four minutes at 6, 500 times G at four degrees Celsius. After removing the supernatant add 750 microliters of cold methanol and resuspend the pellet by sonication using a probe sonicator for five seconds.Then centrifuge the sample for four minutes at 6, 500 times G at four degrees Celsius. And remove the supernatant with a syringe and needle. After washing two more times with cold methanol add 325 microliters of two point five percent SDS in PBS to the protein pellet.Sonicate the sample three times for five seconds. Next heat the sample for five minutes at 65 degrees Celsius. After sonicating centrifuge the sample for five minutes at 6, 500 times G at room temperature.Then transfer the supernatant to a clean 15 milliliter tube and add one point four milliliters of PBS to the supernatant to dilute the SDS concentration to zero point five percent. For streptavidin enrichment first bring the volume of the sample to four point two milliliters with PBS. Then add 40 microliters of a 50%slurry of prewashed streptavidin agarose using a cut end tip.Incubate the mixture for two hours at room temperature with rotation. After centrifuging for two minutes at 1, 400 times G remove the supernatant without drying the bead pellet. Use the residual supernatant to transfer the beads to a one milliliter spin column and wash the column by gravity with one milliliter of one percent SDS in PBS.Continue washing the beads with six molar urea followed by PBS as described in the text protocol. Then use 500 microliters of PBS to transfer the washed beads to a one point five milliliter tube. After centrifuging the sample for two minutes at 1, 400 times G gently aspirate the supernatant with a syringe and needle.To elute the resin bound proteins add 25 microliters of elution buffer to the resin pellet and incubate for 15 minutes at room temperature followed by 15 minutes at 95 degrees Celsius. Add approximately 400 microliters of click chemistry mix to tissue slices which have been prepared according to the text protocol. Pay attention that the chosen volume of click chemistry mix is sufficient to cover the slices.Then incubate the tissue slices for one hour at room temperature protected from light. Following incubation wash the samples with PBS for five minutes and then with cold methanol for five minutes. Next wash the tissue slices three times with a solution of one percent Tween 20 and zero point five millimolar EDTA in PBS for two minutes.Finally wash the slices one more time with PBS for five minutes. After air drying add a drop of antifade mountant with DAPI. Close the samples with cover slips and seal with polish.For probe synthesis undecynenol is activated by dipirydyl carbonate in the presence of catalytic four dimethyl aminyl pyridine to produce a mixed carbonate which is then reacted with the aminyl lactam the beta lactam or head of the probe reacts with the NAAA active site while the terminal alkyne can be functionalized with a reporter tag via click chemistry. ARN 14 six eight six was used to detect NAAA activation in cell extracts of rat inflamed paws by protein block. In naive rats, no NAAA signal is detected.Conversely in rats treated with complete Freunds Adjuvant a marked band corresponding to active NAAA is observed. Another application of ARN 14 six eight six is tissue imaging by fluorescence microscopy. Here red cells represent alveolar macrophages which are positive for active NAAA.NAAA is localized in diffused vesicular structures as appreciable at a higher magnification. After watching this video you should have a good understanding of how to synthesize and use ARN 14 six eight six to detect active NAAA in tissues both by protein blot and fluorescence microscopy. In addition even though this protocol is specific for our target, the probe applications that we describe would be easily adjusted for different activity based probes specific for targets other than NAAA.

preparation-vivo-use-an-activity-based-probe-for-n-acylethanolamine

Research

JoVE Journal

Biochemistry

An Efficient Method for the Isolation of Highly Purified RNA from Seeds for Use in Quantitative Transcriptome Analysis

Plant seeds accumulate large amounts of storage reserves comprising biodegradable organic matter. Humans rely on seed storage reserves for food and as industrial materials. Gene expression profiles are powerful tools for investigating metabolic regulation in plant cells. Therefore, detailed, accurate gene expression profiles during seed development are required for crop breeding. Acquiring highly purified RNA is essential for producing these profiles. Efficient methods are needed to isolate highly purified RNA from seeds. Here, we describe a method for isolating RNA from seeds containing large amounts of oils, proteins, and polyphenols, which have inhibitory effects on high-purity RNA isolation. Our method enables highly purified RNA to be obtained from seeds without the use of phenol, chloroform, or additional processes for RNA purification. This method is applicable to Arabidopsis, rapeseed, and soybean seeds. Our method will be useful for monitoring the expression patterns of low level transcripts in developing and mature seeds.

We have succeeded in establishing a method for RNA isolation from plant seeds containing large amounts of oils, proteins, and polyphenols, which have inhibitory effects on high-purity RNA isolation. Our method is suitable for monitoring the expression of genes with low level transcripts in seeds.

Plant seeds accumulate large amounts of storage reserves comprising biodegradable organic matter. Humans rely on seed storage reserves for food and as ...

Sample Preparation for Mass Spectrometry-based Identification of RNA-binding Regions

Noncoding RNAs play important roles in several nuclear processes, including regulating gene expression, chromatin structure, and DNA repair. In most cases, the action of noncoding RNAs is mediated by proteins whose functions are in turn regulated by these interactions with noncoding RNAs. Consistent with this, a growing number of proteins involved in nuclear functions have been reported to bind RNA and in a few cases the RNA-binding regions of these proteins have been mapped, often through laborious, candidate-based methods.
Here, we report a detailed protocol to perform a high-throughput, proteome-wide unbiased identification of RNA-binding proteins and their RNA-binding regions. The methodology relies on the incorporation of a photoreactive uridine analog in the cellular RNA, followed by UV-mediated protein-RNA crosslinking, and mass spectrometry analyses to reveal RNA-crosslinked peptides within the proteome. Although we describe the procedure for mouse embryonic stem cells, the protocol should be easily adapted to a variety of cultured cells.

We describe a protocol to identify RNA-binding proteins and map their RNA-binding regions in live cells using UV-mediated photocrosslinking and mass spectrometry.

Noncoding RNAs play important roles in several nuclear processes, including regulating gene expression, chromatin structure, and DNA repair. In most ...

Preparation of Keratin Hydrolysate from Chicken Feathers and Its Application in Cosmetics

Keratin hydrolysates (KHs) are established standard components in hair cosmetics. Understanding the moisturizing effects of KH is advantageous for skin-care cosmetics. The goals of the protocol are: (1) to process chicken feathers into KH by alkaline-enzymatic hydrolysis and purify it by dialysis, and (2) to test if adding KH into an ointment base (OB) increases hydration of the skin and improves skin barrier function by diminishing transepidermal water loss (TEWL). During alkaline-enzymatic hydrolysis feathers are first incubated at a higher temperature in an alkaline environment and then, under mild conditions, hydrolyzed with proteolytic enzyme. The solution of KH is dialyzed, vacuum dried, and milled to a fine powder. Cosmetic formulations comprising from oil in water emulsion (O/W) containing 2, 4, and 6 weight% of KH (based on the weight of the OB) are prepared. Testing the moisturizing properties of KH is carried out on 10 men and 10 women at time intervals of 1, 2, 3, 4, 24, and 48 h. Tested formulations are spread at degreased volar forearm sites. The skin hydration of stratum corneum (SC) is assessed by measuring capacitance of the skin, which is one of the most world-wide used and simple methods. TEWL is based on measuring the quantity of water transported per a defined area and period of time from the skin. Both methods are fully non-invasive. KH makes for an excellent occlusive; depending on the addition of KH into OB, it brings about a 30% reduction in TEWL after application. KH also functions as a humectant, as it binds water from the lower layers of the epidermis to the SC; at the optimum KH addition in the OB, up to 19% rise in hydration in men and 22% rise in women occurs.

The goal of the protocol is to prepare keratin hydrolysate from chicken feathers by alkaline-enzymatic hydrolysis and to test whether adding keratin hydrolysate into a cosmetics ointment base improves skin barrier function (heightening hydration and diminishing transepidermal water loss). Tests are conducted on men and woman volunteers.

Keratin hydrolysates (KHs) are established standard components in hair cosmetics. Understanding the moisturizing effects of KH is advantageous for ...

An In Vivo Estrogen Deficiency Mouse Model for Screening Exogenous Estrogen Treatments of Cardiovascular Dysfunction After Menopause

Postmenopausal women are at greater risk of developing cardiovascular diseases than premenopausal women. Female mice ovariectomized (OVX) at weaning display increased atherosclerotic lesions in the aorta compared with female mice with intact ovarian function. However, laboratory models involving estrogen-deficient mice with atherosclerosis-prone status are lacking. This deficit is crucial because clinical estrogen deficiency in menopausal women may aggravate the incidence of pre-existing or ongoing lipid disruption and atherosclerosis. In this study, we establish an in vivo estrogen-deficient mouse model by bilateral ovariectomy via a double dorsal-lateral incision in apolipoprotein E (apoE)-/- mice. We then compare the effects of 17&#946;-estradiol and pseudoprotodioscin (PPD) (a phytoestrogen) perorally administered via hazelnut spread. We find that although PPD exerts some effect on reducing final body weight and plasma TG in OVX apoE-/- mice, it has anti-atherosclerotic and cardiac-protective capacities comparable with its 17&#946;-estradiol counterpart. PPD is a phytoestrogen that has been reported to exert anti-tumor properties. Thus, the proposed method is applicable for screening phytoestrogens via peroral administration to substitute for traditional hormone replacement therapy in postmenopausal women, which has been reported to have potentially deleterious tumorigenetic capacity. Peroral administration via hazelnut spread is noninvasive, rendering it widely applicable to many patients. This article contains step-by-step demonstrations of bilateral ovariectomy via the double dorsal-lateral incision in apoE-/- mice and peroral 17&#946;-estradiol or phytoestrogen hormone replacement via hazelnut spread. Plasma lipid and cardiovascular function analyses using echocardiography follow.

Clinically, estrogen deficiency in menopausal women may aggravate the incidence of lipid disruption and atherosclerosis. We established an in vivo estrogen deficiency model by bilateral ovariectomy via a double dorsal-lateral incision in apoE-/- mice. The mouse model is applicable for screening exogenous estrogen treatments of cardiovascular dysfunction after menopause.

Postmenopausal women are at greater risk of developing cardiovascular diseases than premenopausal women. Female mice ovariectomized (OVX) at weaning ...

Use of Alu Element Containing Minigenes to Analyze Circular RNAs

In addition to linear mRNAs, many eukaryotic genes generate circular RNAs. Most circular RNAs are generated by joining a 5&#39; splice site with an upstream 3&#39; splice site within a pre-mRNA, a process called back-splicing. This circularization is likely aided by secondary structures in the pre-mRNA that bring the splice sites into close proximity. In human genes, Alu elements are thought to promote these secondary RNA structures, as Alu elements are abundant and exhibit base complementarities with each other when present in opposite directions in the pre-mRNA. Here, we describe the generation and analysis of large, Alu element containing reporter genes that form circular RNAs. Through optimization of cloning protocols, reporter genes with up to 20 kb insert length can be generated. Their analysis in co-transfection experiments allows the identification of regulatory factors. Thus, this method can identify RNA sequences and cellular components involved in circular RNA formation.

Use of Alu Element Containing Minigenes to Analyze Circular RNAs

We clone and analyze reporter genes generating circular RNAs. These reporter genes are larger than constructs to analyze linear splicing and contain Alu elements. To investigate the circular RNAs, the constructs are transfected into cells and resulting RNA is analyzed using RT-PCR after removal of linear RNA.

In addition to linear mRNAs, many eukaryotic genes generate circular RNAs. Most circular RNAs are generated by joining a 5&#39; splice site with an ...

Sample Preparation for Probe Electrospray Ionization Mass Spectrometry

Mass spectrometry (MS) is a powerful tool in analytical chemistry because it provides very accurate information about molecules, such as mass-to-charge ratios (m/z), which are useful to deduce molecular weights and structures. While it is essentially a destructive analytical method, recent advancements in the ambient ionization technique have enabled us to acquire data while leaving tissue in a relatively intact state in terms of integrity. Probe electrospray ionization (PESI) is a so-called direct method because it does not require complex and time-consuming pretreatment of samples. A fine needle serves as a sample picker, as well as an ionization emitter. Based on the very sharp and fine property of the probe tip, destruction of the samples is minimal, allowing us to acquire the real-time molecular information from living things in situ. Herein, we introduce three applications of PESI-MS technique that will be useful for biomedical research and development. One involves the application to solid tissue, which is the basic application of this technique for the medical diagnosis. As this technique requires only 10 mg of the sample, it may be very useful in the routine clinical settings. The second application is for in vitro medical diagnostics where human blood serum is measured. The ability to measure fluid samples is also valuable in various biological experiments where a sufficient volume of sample for conventional analytical techniques cannot be provided. The third application leans toward the direct application of probe needles in living animals, where we can obtain real-time dynamics of metabolites or drugs in specific organs. In each application, we can infer the molecules that have been detected by MS or use artificial intelligence to obtain a medical diagnosis.

This article introduces sample preparation methods for a unique real-time analytical method based on the ambient mass spectrometry. This method lets us perform real-time analysis of the biological molecules in vivo without any special pretreatments.

Mass spectrometry (MS) is a powerful tool in analytical chemistry because it provides very accurate information about molecules, such as mass-to-charge ...

Use of Microscale Thermophoresis to Measure Protein-Lipid Interactions

The ability to determine the binding affinity of lipids to proteins is an essential part of understanding protein-lipid interactions in membrane trafficking, signal transduction and cytoskeletal remodeling. Classic tools for measuring such interactions include surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC). While powerful tools, these approaches have setbacks. ITC requires large amounts of purified protein as well as lipids, which can be costly and difficult to produce. Furthermore, ITC as well as SPR are very time consuming, which could add significantly to the cost of performing these experiments. One way to bypass these restrictions is to use the relatively new technique of microscale thermophoresis (MST). MST is fast and cost effective using small amounts of sample to obtain a saturation curve for a given binding event. There currently are two types of MST systems available. One type of MST requires labeling with a fluorophore in the blue or red spectrum. The second system relies on the intrinsic fluorescence of aromatic amino acids in the UV range. Both systems detect the movement of molecules in response to localized induction of heat from an infrared laser. Each approach has its advantages and disadvantages. Label-free MST can use untagged native proteins; however, many analytes, including pharmaceuticals, fluoresce in the UV range, which can interfere with determination of accurate KD values. In comparison, labeled MST allows for a greater diversity of measurable pairwise interactions utilizing fluorescently labeled probes attached to ligands with measurable absorbances in the visible range as opposed to UV, limiting the potential for interfering signals from analytes.

Microscale thermophoresis obtains binding constants quickly at low material cost. Either labeled or label free microscale thermophoresis is commercially available; however, label free thermophoresis is not capable of the diversity of interaction measurements that can be performed using fluorescent labels. We provide a protocol for labeled thermophoresis measurements.

The ability to determine the binding affinity of lipids to proteins is an essential part of understanding protein-lipid interactions in membrane ...

Plant Sample Preparation for Nucleoside/Nucleotide Content Measurement with An HPLC-MS/MS

Nucleosides/nucleotides are building blocks of nucleic acids, parts of cosubstrates and coenzymes, cell signaling molecules, and energy carriers, which are involved in many cell activities. Here, we describe a rapid and reliable method for the absolute qualification of nucleoside/nucleotide contents in plants. Briefly, 100 mg of homogenized plant material was extracted with 1 mL of extraction buffer (methanol, acetonitrile, and water at a ratio of 2:2:1). Later, the sample was concentrated five times in a freeze dryer and then injected into an HPLC-MS/MS. Nucleotides were separated on a porous graphitic carbon (PGC) column and nucleosides were separated on a C18 column. The mass transitions of each nucleoside and nucleotide were monitored by mass spectrometry. The contents of the nucleosides and nucleotides were quantified against their external standards (ESTDs). Using this method, therefore, researchers can easily quantify nucleosides/nucleotides in different plants.

A precise and reproducible method for in vivo nucleosides/nucleotides quantification in plants is described here. This method employs an HPLC-MS/MS.

Nucleosides/nucleotides are building blocks of nucleic acids, parts of cosubstrates and coenzymes, cell signaling molecules, and energy carriers, which ...

Deciphering Molecular Mechanism of Histone Assembly by DNA Curtain Technique

Chromatin is a higher-order structure that packages eukaryotic DNA. Chromatin undergoes dynamic alterations according to the cell cycle phase and in response to environmental stimuli. These changes are essential for genomic integrity, epigenetic regulation, and DNA metabolic reactions such as replication, transcription, and repair. Chromatin assembly is crucial for chromatin dynamics and is catalyzed by histone chaperones. Despite extensive studies, the mechanisms by which histone chaperones enable chromatin assembly remains elusive. Moreover, the global features of nucleosomes organized by histone chaperones are poorly understood. To address these problems, this work describes a unique single-molecule imaging technique named DNA curtain, which facilitates the investigation of the molecular details of nucleosome assembly by histone chaperones. DNA curtain is a hybrid technique that combines lipid fluidity, microfluidics, and total internal reflection fluorescence microscopy (TIRFM) to provide a universal platform for real-time imaging of diverse protein-DNA interactions.Using DNA curtain, the histone chaperone function of Abo1, the Schizosaccharomyces pombe bromodomain-containing AAA+ ATPase, is investigated, and the molecular mechanism underlying histone assembly of Abo1 is revealed. DNA curtain provides a unique approach for studying chromatin dynamics.

DNA curtain, a high-throughput single-molecule imaging technique, provides a platform for real-time visualization of diverse protein-DNA interactions. The present protocol utilizes the DNA curtain technique to investigate the biological role and molecular mechanism of Abo1, a Schizosaccharomyces pombe bromodomain-containing AAA+ ATPase.

Chromatin is a higher-order structure that packages eukaryotic DNA. Chromatin undergoes dynamic alterations according to the cell cycle phase and in ...

Extracellular Glucose Depletion as an Indirect Measure of Glucose Uptake in Cells and Tissues Ex Vivo

The ongoing worldwide epidemic of diabetes increases the demand for the identification of environmental, nutritional, endocrine, genetic, and epigenetic factors affecting glucose uptake. The measurement of intracellular fluorescence is a widely used method to test the uptake of fluorescently-labeled glucose (FD-glucose) in cells in vitro, or for imaging glucose-consuming tissues in vivo. This assay assesses glucose uptake at a chosen time point. The intracellular analysis assumes that the metabolism of FD-glucose is slower than that of endogenous glucose, which participates in catabolic and anabolic reactions and signaling. However, dynamic glucose metabolism also alters uptake mechanisms, which would require kinetic measurements of glucose uptake in response to different factors. This article describes a method for measuring extracellular FD-glucose depletion and validates its correlation with intracellular FD-glucose uptake in cells and tissues ex vivo. Extracellular glucose depletion may be potentially applicable for high-throughput kinetic and dose-dependent studies, as well as identifying compounds with glycemic activity and their tissue-specific effects.

Extracellular Glucose Depletion as an Indirect Measure of Glucose Uptake in Cells and Tissues Ex Vivo

Extracellular depletion of fluorescently labeled glucose correlates with glucose uptake and could be used for high-throughput screening of glucose uptake in excised organs and cell cultures.

The ongoing worldwide epidemic of diabetes increases the demand for the identification of environmental, nutritional, endocrine, genetic, and epigenetic ...