Name: quantitative and qualitative method for sphingomyelin by lc-ms using two stable isotopically labeled sphingomyelin species
Uploaded: 2018-05-07T13:00:00
Description: Watch this Scientific Journal Video about Quantitative and Qualitative Method for Sphingomyelin by LC-MS Using Two Stable Isotopically Labeled Sphingomyelin Species at JoVE.com

This work was supported by a research grant from the Ministry of Education, Culture, Sports, Science and Technology of Japan (KAKENHI) to K.H. (#15K01691), Y.F. (#15K08625), K.Y. (#26461532), and a grant for the study of Intractable Disease Project from Ministry of Health, Labour and Welfare (K.Y. #201510032A). We thank the Edanz Group (www.edanzediting.com/ac) for editing a draft of this manuscript.

Consult all relevant material safety data sheets (MSDS) before use. Wear gloves to minimize sample contamination by skin-derived SM. The present protocol was applied to HeLa cells grown in Eagle&#39;s minimum essential medium supplemented with 10% fetal bovine serum (FBS), 2 mM L-glutamine, 1,000 U/L penicillin, and 100 mg/L streptomycin.
1. Preparation of Lipid Samples
NOTE: It is important that all glassware including test tubes with Teflon-lined screw caps...

<ol>
	<li>Huitema, K., van den Dikkenberg, J., Brouwers, J. F., Holthuis, 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=Identification+of+a+family+of+animal+sphingomyelin+synthases.">Identification of a family of animal sphingomyelin synthases.</a> EMBO J. 23 (1), 33-44 (2004).</li><li>Kihara, Y., Mizuno, H., Chun, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lysophospholipid+receptors+in+drug+discovery.">Lysophospholipid receptors in drug discovery.</a> Exp Cell Res. 333 (2), 171-177 (2015).</li><li>Kihara, A. <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+degradation+pathways,+functions,+and+pathology+of+ceramides+and+epidermal+acylceramides.">Synthesis and degradation pathways, functions, and pathology of ceramides and epidermal acylceramides.</a> Prog Lipid Res. 63, 50-69 (2016).</li><li>Merrill, A. H., Sullards, M. C., Allegood, J. C., Kelly, S., Wang, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sphingolipidomics:+high-throughput,+structure-specific,+and+quantitative+analysis+of+sphingolipids+by+liquid+chromatography+tandem+mass+spectrometry.">Sphingolipidomics: high-throughput, structure-specific, and quantitative analysis of sphingolipids by liquid chromatography tandem mass spectrometry.</a> Methods. 36 (2), 207-224 (2005).</li><li>Houjou, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+and+selective+identification+of+molecular+species+in+phosphatidylcholine+and+sphingomyelin+by+conditional+neutral+loss+scanning+and+MS3.">Rapid and selective identification of molecular species in phosphatidylcholine and sphingomyelin by conditional neutral loss scanning and MS3.</a> Rapid Commun Mass Spectrom. 18 (24), 3123-3130 (2004).</li><li>Hama, K., Fujiwara, Y., Tabata, H., Takahashi, H., Yokoyama, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comprehensive+Quantitation+Using+Two+Stable+Isotopically+Labeled+Species+and+Direct+Detection+of+N-Acyl+Moiety+of+Sphingomyelin.">Comprehensive Quantitation Using Two Stable Isotopically Labeled Species and Direct Detection of N-Acyl Moiety of Sphingomyelin.</a> Lipids. , (2017).</li><li>Bligh, E. G., Dyer, W. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rapid+method+of+total+lipid+extraction+and+purification.">A rapid method of total lipid extraction and purification.</a> Can. J. Biochem. Physiol. 37, 911-917 (1959).</li><li>Gu, H., Liu, G., Wang, J., Aubry, A. F., Arnold, M. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selecting+the+correct+weighting+factors+for+linear+and+quadratic+calibration+curves+with+least-squares+regression+algorithm+in+bioanalytical+LC-MS/MS+assays+and+impacts+of+using+incorrect+weighting+factors+on+curve+stability,+data+quality,+and+assay+performance.">Selecting the correct weighting factors for linear and quadratic calibration curves with least-squares regression algorithm in bioanalytical LC-MS/MS assays and impacts of using incorrect weighting factors on curve stability, data quality, and assay performance.</a> Anal Chem. 86 (18), 8959-8966 (2014).</li><li>Folch, J., Lees, M., Sloane Stanley, G. H. <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+method+for+the+isolation+and+purification+of+total+lipides+from+animal+tissues.">A simple method for the isolation and purification of total lipides from animal tissues.</a> J Biol Chem. 226 (1), 497-509 (1957).</li><li>Thomas, M. 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=Ozone-induced+dissociation:+elucidation+of+double+bond+position+within+mass-selected+lipid+ions.">Ozone-induced dissociation: elucidation of double bond position within mass-selected lipid ions.</a> Anal Chem. 80 (1), 303-311 (2008).</li><li>Baba, T., Campbell, J. L., Le Blanc, J. C., Baker, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In-depth+sphingomyelin+characterization+using+electron+impact+excitation+of+ions+from+organics+and+mass+spectrometry.">In-depth sphingomyelin characterization using electron impact excitation of ions from organics and mass spectrometry.</a> J Lipid Res. 57 (5), 858-867 (2016).</li><li>Ryan, E., Nguyen, C. Q. N., Shiea, C., Reid, G. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detailed+Structural+Characterization+of+Sphingolipids+via+193+nm+Ultraviolet+Photodissociation+and+Ultra+High+Resolution+Tandem+Mass+Spectrometry.">Detailed Structural Characterization of Sphingolipids via 193 nm Ultraviolet Photodissociation and Ultra High Resolution Tandem Mass Spectrometry.</a> J Am Soc Mass Spectrom. , (2017).</li><li>Pham, H. T., Ly, T., Trevitt, A. J., Mitchell, T. W., Blanksby, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differentiation+of+complex+lipid+isomers+by+radical-directed+dissociation+mass+spectrometry.">Differentiation of complex lipid isomers by radical-directed dissociation mass spectrometry.</a> Anal Chem. 84 (17), 7525-7532 (2012).</li></ol>

In the present qualitative method, we obtained MS3 product ions of a SPC and an N-acyl moiety. It is critical to properly assign both a SPC and an N-acyl moiety. To this end, it should be noted that other phosphorylcholine-containing molecules can also be detected as MS3 product ions. Diacyl-phosphatidylcholine (PC) and plasmalogen-PC are abundantly present in mammalian cells, and their hydrophobicity is similar to that of SM. Therefore, diacyl-PC and plasmalogen-PC with an isotope...

Sphingomyelin (SM) is a common sphingolipid in mammalian cells. SM is synthesized intracellularly1 and present as a precursor for other sphingolipids such as a sphingosine-1-phosphate and a ceramide, which have crucial roles in immune cell trafficking and skin barrier homeostasis, respectively2,3. Thus, the precise analysis of the SM metabolism is important for elucidating the physiological and pathological roles of sphingolipids.
SM is composed of a ceramide and a phosphorylcholine that is linked to the 1-hydroxy group of the ceramide, which is further composed of a sphingosine and an N-acyl moiety. A variety in the carbon and double bond numbers in both the sphingosine and N-acyl moiety results in the number of ceramide (and SM) species. Recent advances in LC-ESI-MS/MS has enabled quantitative and qualitative analysis of SM4,5. In the qualitative analysis, the number of carbon and double bonds of a sphingoid LCB of SM was identified by assigning product ion spectra of LCB. However, structural information of the N-acyl moiety was not directly obtained because its corresponding product ions have not been reported, and therefore N-acyl moieties were deduced by differential analysis between precursor ions and product ions corresponding to LCB in both positive and negative ion modes4,5. In this report, we present a method to detect the product ions of both LCB and N-acyl moiety simultaneously in MS3 mode using triple quadrupole and quadrupole linear ion trap mass spectrometry, which facilitates the precise structural speculation of each SM species6.
The ion suppression (or enhancement) effects caused by the matrix in biological samples hamper the accurate quantification in LC-ESI-MS analysis, and therefore, it is desirable to construct calibration curves for all analytes of interest in the identical matrix of the biological sample. However, this strategy is not feasible because it is almost impossible to prepare all SM species in biological samples, especially in comprehensive analysis. Thus, it is practical to construct a calibration curve and determine the quantitative range using a representative SM species spiked in the biological samples. We used two isotopically-labeled SM species to construct a calibration curve; one was used for an internal standard and the other for a standard compound. We detected a small amount of isotopically-labeled SM species as a standard compound spiked in biological samples and successfully obtained a calibration curve and the quantitative range6.

<table border="0" cellpadding="0" cellspacing="0" style="width:737px;" width="738">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">PBS</td>
			<td style="width:131px;">ThermoFisher</td>
			<td style="width:119px;">10010023</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">100 mm tissue culture dish</td>
			<td style="width:131px;">IWAKI</td>
			<td style="width:119px;">3020-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Cell scraper</td>
			<td style="width:131px;">IWAKI</td>
			<td style="width:119px;">9000-220</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Siliconized 2.0 mL tube</td>
			<td style="width:131px;">Fisher Scientific</td>
			<td style="width:119px;">02-681-321</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Test tube</td>
			<td style="width:131px;">IWAKI</td>
			<td style="width:119px;">TST SCR 16-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Teflon-lined screw cap</td>
			<td style="width:131px;">IWAKI</td>
			<td style="width:119px;">9998CAP415-15</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Disposable glass tube</td>
			<td style="width:131px;">IWAKI</td>
			<td style="width:119px;">9832-1310</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:321px;">CAPCELL PAK C18 ACR 3 &#181;m 1.5 mm I.D. x 100 mm</td>
			<td style="width:131px;">Shiseido</td>
			<td style="width:119px;">92223</td>
			<td>Guard cartridge is inserted into cartridge holder, and linked to C18 column</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:321px;">CAPCELL C18 MGII S-3 2.0 mm x 10 mm GUARD CARTRIDGE</td>
			<td style="width:131px;">Shiseido</td>
			<td style="width:119px;">12197</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Cartridge holder</td>
			<td style="width:131px;">Shiseido</td>
			<td style="width:119px;">12415</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Acetonitrile</td>
			<td style="width:131px;">Wako</td>
			<td style="width:119px;">018-19853</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">2-Propanol (Isopropyl Alcohol)</td>
			<td style="width:131px;">Wako</td>
			<td style="width:119px;">161-09163</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Methanol</td>
			<td style="width:131px;">Wako</td>
			<td style="width:119px;">134-14523</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Formic acid</td>
			<td style="width:131px;">Wako</td>
			<td style="width:119px;">066-00466</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">28% Ammonia water</td>
			<td style="width:131px;">Wako</td>
			<td style="width:119px;">016-03146</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Sonicator (bath type)</td>
			<td style="width:131px;">SHARP</td>
			<td style="width:119px;">UT-206H</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Vortex mixer for glass test tube</td>
			<td style="width:131px;">TAITEC</td>
			<td style="width:119px;">Mix-EVR</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">1.4 mL glass vial</td>
			<td style="width:131px;">Tomsic</td>
			<td style="width:119px;">500-1982</td>
			<td>Samples are stored in 1.4 mL glass vial sealed with screw cap and 8 mm septum at -20&#176;C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">8 mm septum</td>
			<td style="width:131px;">Tomsic</td>
			<td style="width:119px;">200-3322</td>
			<td>When samples are analyzed, screw caps are replaced with screw caps with slit septum</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Screw cap for 1.4 mm glass vial</td>
			<td style="width:131px;">Tomsic</td>
			<td style="width:119px;">500-2762</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Screw cap with slit septum</td>
			<td style="width:131px;">Shimadzu GLC</td>
			<td style="width:119px;">GLCTV-803</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">PVDF 0.22 &#181;m filter</td>
			<td style="width:131px;">Millipore</td>
			<td style="width:119px;">SLGVR04NL</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:321px;">Triple quadrupole and quadrupole linear ion trap mass spectrometry</td>
			<td style="width:131px;">SCIEX</td>
			<td style="width:119px;">QTRAP4500</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:321px;">The software for data acquisition and analysis of product ion spectra</td>
			<td style="width:131px;">SCIEX</td>
			<td style="width:119px;">Analyst</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:321px;">The software for data integration in quantitative analysis</td>
			<td style="width:131px;">SCIEX</td>
			<td style="width:119px;">MultiQuant</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">HPLC system</td>
			<td style="width:131px;">Shimadzu</td>
			<td style="width:119px;">Nexera</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Glass bottle</td>
			<td style="width:131px;">Sansyo</td>
			<td style="width:119px;">85-0002</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">d18:1/24:0 sphingomyelin</td>
			<td style="width:131px;">Avanti Polar Lipids</td>
			<td style="width:119px;">860592P</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Sphingosylphosphorylcholine</td>
			<td style="width:131px;">Merck</td>
			<td style="width:119px;">567735</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fetal bovine serum</td>
			<td style="width:131px;">ThermoFisher&#160;</td>
			<td style="width:119px;">26140079</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">L-glutamine</td>
			<td style="width:131px;">ThermoFisher&#160;</td>
			<td style="width:119px;">25030081</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:321px;">Penicillin and streptomycin</td>
			<td style="width:131px;">Sigma</td>
			<td style="width:119px;">P4333</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Eagle&#8217;s minimum essential medium</td>
			<td style="width:131px;">Sigma</td>
			<td style="width:119px;">M4655</td>
			<td></td>
		</tr>
	</tbody>
</table>

quantitative and qualitative method for sphingomyelin by lc-ms using two stable isotopically labeled sphingomyelin species

We present a method of analyzing sphingomyelin (SM) qualitatively and quantitatively by liquid chromatography-electrospray Ionization-tandem mass spectrometry (LC-ESI-MS/MS). SM is a common sphingolipid composed of a phosphorylcholine and a ceramide as the hydrophilic and hydrophobic component, respectively. A number of SM species are present in mammalian cells due to a variety in the sphingoid long chain base (LCB) and an N-acyl moiety in the ceramide. In this report, we show a method of estimating the number of carbon and double bonds in a LCB and an N-acyl moiety based on their corresponding product ions in MS/MS/MS (MS3) experiments. In addition, we present a quantitative analysis method for SM using two stable isotopically labeled SM species, which facilitates determining the range used in SM quantitation. The present method will be useful in characterizing a variety of SM species in biological samples and industrial products such as cosmetics.

Chemically synthesized d18:1/24:0 SM (Figure 1A) and d18:1/24:0 SM in lipid samples extracted from HeLa cells (Figure 1B) were analyzed by LC-ESI-MS3 employing [M+HCOO]- and [M-CH3]- as first and second precursor ions, respectively. Note that the spectrum intensity of demethylated-sphingosylphosphorylcholine (SPC) (m/z 449) is larger than that ...

Watch this Scientific Journal Video about Quantitative and Qualitative Method for Sphingomyelin by LC-MS Using Two Stable Isotopically Labeled Sphingomyelin Species at JoVE.com

Quantitative and Qualitative Method for Sphingomyelin by LC-MS Using Two Stable Isotopically Labeled Sphingomyelin Species

Here, we present a protocol to quantify and qualify each sphingomyelin species using multiple reaction monitoring and MS/MS/MS mode, respectively.

We present a method of analyzing sphingomyelin (SM) qualitatively and quantitatively by liquid chromatography-electrospray Ionization-tandem mass ...

The overall goal of this procedure is to precisely analyze the amount and the structure of each Sphingomyelin species in biological samples. This method can help answer key questions in the lipid field pertaining to lipid biology and lipid The main advantage of this technique is that we can characterize a variety of Sphingomyelin species in biological samples by chromatography mass spectrometry system. To begin, remove the culture media from a 10 centimeter tissue culture dish containing HeLa cells and rinse the cells twice with six milliliters of ice cold PBS.Then add one milliliter of the ice cold PBS into the 10 centimeter tissue culture dish and use a cell scraper to harvest the cells. Once removed from the dish's surface, transfer the cells into two milliliter siliconized plastic tubes. Following centrifugation, remove the supernatant and add one milliliter methanol to each cell pellet.Then briefly vortex the tubes. Next, place the samples into a bath-type sonicator and sonicate at 200 watts for five minutes. When finished, transfer the whole cell homogenate into test tubes equipped with Teflon lined screw caps.Now add one milliliter of methanol, one milliliter of chloroform, 0.8 milliliters of double distilled water in 50 microliters of 10 micromolar of an internal standard into each test tube. Cap the tubes and vortex them vigorously at 2, 500 rpm for five minutes at room temperature. Then add an additional one milliliter of chloroform and one milliliter of double distilled water to each tube.Again, vortex the tubes vigorously at 2, 500 rpm for five minutes at room temperature. Next, centrifuge the samples in order to completely separate the aqueous and organic phases. Transfer the lower phase into disposable glass tubes.Add two milliliters of chloroform into the test tubes. Then vortex the tubes vigorously at 2, 500 rpm for five minutes at room temperature to sufficiently mix with the upper phase and interphasial fluff. Following a second centrifugation, transfer the modified lower phase into the disposable glass tubes along with the initial lower phase.Now place the glass tubes under a nitrogen stream for approximately 60 minutes and completely remove the organic solvents in the collected lower phase. Finally, reconstitute the samples with 500 microliters of methanol or ethanol. Filter the resulting mixture with a 0.02 micron filter into glass vials.Then store the sample at minus 20 degrees Celsius. Perform serial dilutions of the standard compound and add 50 microliters of each concentration into separate test tubes. Next, prepare three quality control samples by adding an amount within three times the lower boundary of the standard curve to the first sample, an amount near the center of the curve for the second sample, and an amount near the upper boundary of the standard curve for the third sample.Then add the cell homogenate in one milliliter of methanol into each test tube and extract the total lipid fraction from each sample using the method just shown. To begin, prepare the mobile phase. Mix together acetonitrile, methanol, and double distilled water at a two to two to one ratio for the aqueous phase.Use isopropanol for the organic phase in glass bottles with Teflon lined screw caps. Then sonicate both of the mobile phases for five minutes in a bath-type sonicator. Then add formic acid to a final concentration of 26.4 millimolar and ammonium hydroxide at 14.9 millimolar into each mobile phase.For qualitative analysis, activate the high performance liquid chromatography system. Put inlet tubes into the glass bottles that contain the mobile phases and purge the HPLC lines. Then link a C18 HPLC column to the HPLC system.Keep the temperature in the column oven at 50 degrees Celsius and condition the column with the aqueous mobile phase at 100 microliters per minute. During the run, place the samples into a sample rack of the auto sampler. Set the parameters of the triple quadruple and quadruple linear ion trap mass spectrometry system for three-stage mass spectrometry analysis as listed in table one and table two of the accompanying text protocol.Also, set the parameters for the first and second precursor ions of the SM species of interest as described in more detail in the accompanying text protocol. Create a batch file and submit the batch file to obtain the data of MS three product ion spectra of each Sphingomyelin species by liquid chromatography electrospray ionization tandem mass spectrometric analysis. Obtain the three-phase MS product ion spectra of the Sphingomyelin species of interest by liquid chromatography electrospray ionization tandem mass spectrometry analysis.Then assign each MS three product ion spectra of the Sphingomyelin by comparing the mass to charge ratio of the product ion spectra in the exact mass of the Sphingoid long-chain base and n-acyl moiety of interest. Quantitatively analyze the Sphingomyelin using liquid chromatography electrospray ionization tandem mass spectrometry analysis as described in the accompanying text protocol. Then process the multiple reaction monitoring data using the software for data integration to obtain the data of the peak area for the extracted ion chromatogram of each Sphingomyelin species.Quantify each Sphingomyelin species and construct the standard curves as described in the accompanying text protocol. The spectrum of both chemically synthesized Sphingomyelin and Sphingomyelin in lipid samples extracted from HeLa cells are shown here. Of note, the spectrum intensity of demethylated sphingosylphosphorylcholine is larger than that of the SM n-acyl moiety in both samples.Also of interest, the spectrum corresponding to sphingosine-1-phosphate is useful to speculate the number of carbon and double bonds of the sphingoid long-chain base of the Sphingomyelin. In the present quantitative method, it is critical to precisely prepare samples for constructing the calibration curve in validating this method. The curve fitting up low concentration was clearly improved by using the weighting factor equals one over x squared as compared with that using the weighting factor of one or one over x.This technique paved the way for researchers in the field of biology and industry to characterize a variety of Sphingomyelin species in biological samples and industry products such as cosmetics. After watching this video, you should have a good understanding of how to precisely analyze the amount and the structure of each Sphingomyelin species in biological samples. Don't forget that working with absorbents can be extremely hazardous and precautions such as using proper glass wears should always be taken while performing this procedure.In addition, it is important to wear gloves to prevent the contamination of lipids derived from your hands.

quantitative-qualitative-method-for-sphingomyelin-lc-ms-using-two

Research

JoVE Journal

Biochemistry

A Method for Measuring Metabolism in Sorted Subpopulations of Complex Cell Communities Using Stable Isotope Tracing

Mammalian cell types exhibit specialized metabolism, and there is ample evidence that various co-existing cell types engage in metabolic cooperation. Moreover, even cultures of a single cell type may contain cells in distinct metabolic states, such as resting or cycling cells. Methods for measuring metabolic activities of such subpopulations are valuable tools for understanding cellular metabolism. Complex cell populations are most commonly separated using a cell sorter, and subpopulations isolated by this method can be analyzed by metabolomics methods. However, a problem with this approach is that the cell sorting procedure subjects cells to stresses that may distort their metabolism.
To overcome these issues, we reasoned that the mass isotopomer distributions (MIDs) of metabolites from cells cultured with stable isotope-labeled nutrients are likely to be more stable than absolute metabolite concentrations, because MIDs are formed over longer time scales and should be less affected by short-term exposure to cell sorting conditions. Here, we describe a method based on this principle, combining cell sorting with liquid chromatography-high resolution mass spectrometry (LC-HRMS). The procedure involves analyzing three types of samples: (1) metabolite extracts obtained directly from the complex population; (2) extracts of "mock sorted" cells passed through the cell sorter instrument without gating any specific population; and (3) extracts of the actual sorted populations. The mock sorted cells are compared against direct extraction to verify that MIDs are indeed not altered by the cell sorting procedure itself, prior to analyzing the actual sorted populations. We show example results from HeLa cells sorted according to cell cycle phase, revealing changes in nucleotide metabolism.

This article describes a method for studying cellular metabolism in complex communities of multiple cell types, using a combination of stable isotope tracing, cell sorting to isolate specific cell types, and mass spectrometry.

Mammalian cell types exhibit specialized metabolism, and there is ample evidence that various co-existing cell types engage in metabolic cooperation. ...

A Protein Preparation Method for the High-throughput Identification of Proteins Interacting with a Nuclear Cofactor Using LC-MS/MS Analysis

Transcriptional coregulators are vital to the efficient transcriptional regulation of nuclear chromatin structure. Coregulators play a variety of roles in regulating transcription. These include the direct interaction with transcription factors, the covalent modification of histones and other proteins, and the occasional chromatin conformation alteration. Accordingly, establishing relatively quick methods for identifying proteins that interact within this network is crucial to enhancing our understanding of the underlying regulatory mechanisms. LC-MS/MS-mediated protein binding partner identification is a validated technique used to analyze protein-protein interactions. By immunoprecipitating a previously-identified member of a protein complex with an antibody (occasionally with an antibody for a tagged protein), it is possible to identify its unknown protein interactions via mass spectrometry analysis. Here, we present a method of protein preparation for the LC-MS/MS-mediated high-throughput identification of protein interactions involving nuclear cofactors and their binding partners. This method allows for a better understanding of the transcriptional regulatory mechanisms of the targeted nuclear factors.

We have established a method for the purification of coregulatory interaction proteins using the LC-MS/MS system.

Transcriptional coregulators are vital to the efficient transcriptional regulation of nuclear chromatin structure. Coregulators play a variety of roles in ...

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 ...

Efficient Purification and LC-MS/MS-based Assay Development for Ten-Eleven Translocation-2 5-Methylcytosine Dioxygenase

The epigenetic transcription regulation mediated by 5-methylcytosine (5mC) has played a critical role in eukaryotic development. Demethylation of these epigenetic marks is accomplished by sequential oxidation by ten-eleven translocation dioxygenases (TET1-3), followed by the thymine-DNA glycosylase-dependent base excision repair. Inactivation of the TET2 gene due to genetic mutations or by other epigenetic mechanisms is associated with a poor prognosis in patients with diverse cancers, especially hematopoietic malignancies. Here, we describe an efficient single step purification of enzymatically active untagged human TET2 dioxygenase using cation exchange chromatography. We further provide a liquid chromatography-tandem mass spectrometry (LC-MS/MS) approach that can separate and quantify the four normal DNA bases (A, T, G, and C), as well as the four modified cytosine bases (5-methyl, 5-hydroxymethyl, 5-formyl, and 5-carboxyl). This assay can be used to evaluate the activity of wild type and mutant TET2 dioxygenases.

Here, we present a protocol for an efficient single step purification of the active untagged human ten-eleven translocation-2 (TET2) 5-methylcytosine dioxygenase using ion-exchange chromatography and its assay using a liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based approach.

The epigenetic transcription regulation mediated by 5-methylcytosine (5mC) has played a critical role in eukaryotic development. Demethylation of these ...

Ubiquitin Chain Analysis by Parallel Reaction Monitoring

Assessment of the global profile of ubiquitin chain topologies within a proteome is of interest to answer a wide range of biological questions. The protocol outlined here takes advantage of the di-glycine (-GG) modification left after the tryptic digestion of ubiquitin incorporated in a chain. By quantifying these topology-characteristic peptides the relative abundance of each ubiquitin chain topology can be determined. The steps required to quantify these peptides by a parallel reaction monitoring experiment are reported taking into consideration the stabilization of ubiquitin chains. Preparation of heavy controls, cell lysis, and digestion are described along with the appropriate mass spectrometer setup and data analysis workflow. An example data set with perturbations in ubiquitin topology is presented, accompanied by examples of how optimization of the protocol can affect results. By following the steps outlined, a user will be able to perform a global assessment of the ubiquitin topology landscape within their biological context.

This method describes the assessment of global changes in ubiquitin chain topology. The assessment is performed by the application of a mass spectrometry-based targeted proteomics approach.

Assessment of the global profile of ubiquitin chain topologies within a proteome is of interest to answer a wide range of biological questions. The ...

Single-Molecule Imaging of EWS-FLI1 Condensates Assembling on DNA

The fusion genes resulting from chromosomal translocation have been found in many solid tumors or leukemia. EWS-FLI1, which belongs to the FUS/EWS/TAF15 (FET) family of fusion oncoproteins, is one of the most frequently involved fusion genes in Ewing sarcoma. These FET family fusion proteins typically harbor a low-complexity domain (LCD) of FET protein at their N-terminus and a DNA-binding domain (DBD) at their C-terminus. EWS-FLI1 has been confirmed to form biomolecular condensates at its target binding loci due to LCD-LCD and LCD-DBD interactions, and these condensates can recruit RNA polymerase II to enhance gene transcription. However, how these condensates are assembled at their binding sites remains unclear. Recently, a single-molecule biophysics method-DNA Curtains-was applied to visualize these assembling processes of EWS-FLI1 condensates. Here, the detailed experimental protocol and data analysis approaches are discussed for the application of DNA Curtains in studying the biomolecular condensates assembling on target DNA.

Here, we describe the use of the single-molecule imaging method, DNA Curtains, to study the biophysical mechanism of EWS-FLI1 condensates assembling on DNA.

The fusion genes resulting from chromosomal translocation have been found in many solid tumors or leukemia. EWS-FLI1, which belongs to the FUS/EWS/TAF15 ...

A Robust Single-Particle Cryo-Electron Microscopy (cryo-EM) Processing Workflow with cryoSPARC, RELION, and Scipion

Recent advances in both instrumentation and image processing software have made single-particle cryo-electron microscopy (cryo-EM) the preferred method for structural biologists to determine high-resolution structures of a wide variety of macromolecules. Multiple software suites are available to new and expert users for image processing and structure calculation, which streamline the same basic workflow: movies acquired by the microscope detectors undergo correction for beam-induced motion and contrast transfer function (CTF) estimation. Next, particle images are selected and extracted from averaged movie frames for iterative 2D and 3D classification, followed by 3D reconstruction, refinement, and validation. Because various software packages employ different algorithms and require varying levels of expertise to operate, the 3D maps they generate often differ in quality and resolution. Thus, users regularly transfer data between a variety of programs for optimal results. This paper provides a guide for users to navigate a workflow across the popular software packages: cryoSPARC v3, RELION-3, and Scipion 3 to obtain a near-atomic resolution structure of the adeno-associated virus (AAV). We first detail an image processing pipeline with cryoSPARC v3, as its efficient algorithms and easy-to-use GUI allow users to quickly arrive at a 3D map. In the next step, we use PyEM and in-house scripts to convert and transfer particle coordinates from the best quality 3D reconstruction obtained in cryoSPARC v3 to RELION-3 and Scipion 3 and recalculate 3D maps. Finally, we outline steps for further refinement and validation of the resultant structures by integrating algorithms from RELION-3 and Scipion 3. In this article, we describe how to effectively utilize three processing platforms to create a single and robust workflow applicable to a variety of data sets for high-resolution structure determination.

A Robust Single-Particle Cryo-Electron Microscopy cryo-EM Processing Workflow with cryoSPARC, RELION, and Scipion

This article describes how to effectively utilize three cryo-EM processing platforms, i.e., cryoSPARC v3, RELION-3, and Scipion 3, to create a single and robust workflow applicable to a variety of single-particle data sets for high-resolution structure determination.

Recent advances in both instrumentation and image processing software have made single-particle cryo-electron microscopy (cryo-EM) the preferred method ...

Analyzing the Interaction of Fluorescent-Labeled Proteins with Artificial Phospholipid Microvesicles using Quantitative Flow Cytometry

In the human body, most of the major physiologic reactions involved in the immune response and blood coagulation proceed on the membranes of cells. An important first step in any membrane-dependent reaction is binding of protein on the phospholipid membrane. An approach to studying protein interaction with lipid membranes has been developed using fluorescently labeled proteins and flow cytometry. This method allows the study of protein-membrane interactions using live cells and natural or artificial phospholipid vesicles. The advantage of this method is the simplicity and availability of reagents and equipment. In this method, proteins are labeled using fluorescent dyes. However, both self-made and commercially available, fluorescently labeled proteins can be used. After conjugation with a fluorescent dye, the proteins are incubated with a source of the phospholipid membrane (microvesicles or cells), and the samples are analyzed by flow cytometry. The obtained data can be used to calculate the kinetic constants and equilibrium Kd. In addition, it is possible to estimate the approximate number of protein binding sites on the phospholipid membrane using special calibration beads.

Here, we describe a set of methods for characterizing the interaction of proteins with membranes of cells or microvesicles.

In the human body, most of the major physiologic reactions involved in the immune response and blood coagulation proceed on the membranes of cells. An ...

Stable Isotope Tracing &amp; LC-MS Analysis to Measure DHODH and SDH Activities

Oxygen-Independent Assays to Measure Mitochondrial Function in Mammals

The flow of electrons in the mitochondrial electron transport chain (ETC) supports multifaceted biosynthetic, bioenergetic, and signaling functions in mammalian cells. As oxygen (O2) is the most ubiquitous terminal electron acceptor for the mammalian ETC, the O2 consumption rate is frequently used as a proxy for mitochondrial function. However, emerging research demonstrates that this parameter is not always indicative of mitochondrial function, as fumarate can be employed as an alternative electron acceptor to sustain mitochondrial functions in hypoxia. This article compiles a series of protocols that allow researchers to measure mitochondrial function independently of the O2 consumption rate. These assays are particularly useful when studying mitochondrial function in hypoxic environments. Specifically, we describe methods to measure mitochondrial ATP production, de novo pyrimidine biosynthesis, NADH oxidation by complex I, and superoxide production. In combination with classical respirometry experiments, these orthogonal and economical assays will provide researchers with a more comprehensive assessment of mitochondrial function in their system of interest.

Author Spotlight: Oxygen-Independent Assays to Measure Mitochondrial Function in Mammals  

Here, we present a compilation of assays to directly measure mitochondrial function in mammalian cells independently of their ability to consume molecular oxygen.

The flow of electrons in the mitochondrial electron transport chain (ETC) supports multifaceted biosynthetic, bioenergetic, and signaling functions in ...