Ces travaux ont été appuyés par le Conseil de recherches en sciences naturelles et en génie du Canada, le Fonds de recherche du Québec nature et technologie, la Fondation canadienne pour l’innovation et les fonds de démarrage de l’Université McGill.

<ol>
	<li>Karplus, M., McCammon, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+dynamics+simulations+of+biomolecules.">Molecular dynamics simulations of biomolecules.</a> Nature Structural &amp; Molecular Biology. 9 (9), 646-652 (2002).</li><li>Campbell, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+protein+dynamics+in+the+evolution+of+new+enzyme+function.">The role of protein dynamics in the evolution of new enzyme function.</a> Nature Chemical Biology. 12 (11), 944-950 (2016).</li><li>Tokuriki, N., Tawfik, D. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Protein+dynamism+and+evolvability.">Protein dynamism and evolvability.</a> Science. 324 (5924), 203-207 (2009).</li><li>Wales, T. E., Engen, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+exchange+mass+spectrometry+for+the+analysis+of+protein+dynamics.">Hydrogen exchange mass spectrometry for the analysis of protein dynamics.</a> Mass Spectrometry Reviews. 25 (1), 158-170 (2006).</li><li>Konermann, L., Pan, J., Liu, Y. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen+exchange+mass+spectrometry+for+studying+protein+structure+and+dynamics.">Hydrogen exchange mass spectrometry for studying protein structure and dynamics.</a> Chemical Society Reviews. 40 (3), 1224 (2011).</li><li>Katta, V., Chait, B. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conformational+changes+in+proteins+probed+by+hydrogen-exchange+electrospray-ionization+mass+spectrometry.">Conformational changes in proteins probed by hydrogen-exchange electrospray-ionization mass spectrometry.</a> Rapid Communications in Mass Spectrometry. 5 (4), 214 (1991).</li><li>Zhang, Z., Smith, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+amide+hydrogen+exchange+by+mass+spectrometry:+a+new+tool+for+protein+structure+elucidation.">Determination of amide hydrogen exchange by mass spectrometry: a new tool for protein structure elucidation.</a> Protein Science. 2 (4), 522 (1993).</li><li>Smith, D. L., Deng, Y., Zhang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+the+non-covalent+structure+of+proteins+by+amide+hydrogen+exchange+and+mass+spectrometry.">Probing the non-covalent structure of proteins by amide hydrogen exchange and mass spectrometry.</a> Journal of Mass Spectrometry. 32 (2), 135-146 (1997).</li><li>Bai, Y., Milne, J. S., Mayne, L., Englander, S. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primary+structure+effects+on+peptide+group+hydrogen+exchange.">Primary structure effects on peptide group hydrogen exchange.</a> Proteins. 17 (1), 75-86 (1993).</li><li>Xiao, K., 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=Revealing+the+architecture+of+protein+complexes+by+an+orthogonal+approach+combining+HDXMS,+CXMS,+and+disulfide+trapping.">Revealing the architecture of protein complexes by an orthogonal approach combining HDXMS, CXMS, and disulfide trapping.</a> Nature Protocols. 13 (6), 1403-1428 (2018).</li><li>Smith, D. L., Deng, Y., Zhang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Probing+the+non-covalent+structure+of+proteins+by+amide+hydrogen+exchange+and+mass+spectrometry.">Probing the non-covalent structure of proteins by amide hydrogen exchange and mass spectrometry.</a> Journal of Mass Spectrometry. 32 (2), 135-146 (1997).</li><li>Masson, G. 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=Recommendations+for+performing,+interpreting+and+reporting+hydrogen+deuterium+exchange+mass+spectrometry+(HDX-MS)+experiments.">Recommendations for performing, interpreting and reporting hydrogen deuterium exchange mass spectrometry (HDX-MS) experiments.</a> Nature Methods. 16 (7), 595-602 (2019).</li><li>Liu, 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=An+Efficient+Site-Specific+Method+for+Irreversible+Covalent+Labeling+of+Proteins+with+a+Fluorophore.">An Efficient Site-Specific Method for Irreversible Covalent Labeling of Proteins with a Fluorophore.</a> Scientific Reports. 5, 16883 (2015).</li><li>Marion, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Overcoming+the+overlap+problem+in+the+assignment+of+proton+NMR+spectra+of+larger+proteins+by+use+of+three-dimensional+heteronuclear+proton-nitrogen-15+Hartmann-Hahn-multiple+quantum+coherence+and+nuclear+Overhauser-multiple+quantum+coherence+spectroscopy:+application+to+interleukin+1.beta.">Overcoming the overlap problem in the assignment of proton NMR spectra of larger proteins by use of three-dimensional heteronuclear proton-nitrogen-15 Hartmann-Hahn-multiple quantum coherence and nuclear Overhauser-multiple quantum coherence spectroscopy: application to interleukin 1.beta.</a> Biochemistry. 28 (15), 6150-6156 (1989).</li><li>Balasubramaniam, D., Komives, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen-exchange+mass+spectrometry+for+the+study+of+intrinsic+disorder+in+proteins.">Hydrogen-exchange mass spectrometry for the study of intrinsic disorder in proteins.</a> Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics. 1834 (6), 1202-1209 (2013).</li><li>Goswami, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Time+window+expansion+for+HDX+analysis+of+an+intrinsically+disordered+protein.">Time window expansion for HDX analysis of an intrinsically disordered protein.</a> Journal of the American Society for Mass Spectrometry. 24 (10), 1584-1592 (2013).</li><li>Keppel, T. R., Howard, B. A., Weis, D. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mapping+Unstructured+Regions+and+Synergistic+Folding+in+Intrinsically+Disordered+Proteins+with+Amide+H/D+Exchange+Mass+Spectrometry.">Mapping Unstructured Regions and Synergistic Folding in Intrinsically Disordered Proteins with Amide H/D Exchange Mass Spectrometry.</a> Biochemistry. 50 (40), 8722-8732 (2011).</li><li>Mitchell, J. L., 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=Functional+Characterization+and+Conformational+Analysis+of+the+Herpesvirus+saimiri+Tip-C484+Protein.">Functional Characterization and Conformational Analysis of the Herpesvirus saimiri Tip-C484 Protein.</a> Journal of Molecular Biology. 366 (4), 1282-1293 (2007).</li><li>Pan, J., Han, J., Borchers, C. H., Konermann, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrogen/deuterium+exchange+mass+spectrometry+with+top-down+electron+capture+dissociation+for+characterizing+structural+transitions+of+a+17+kDa+protein.">Hydrogen/deuterium exchange mass spectrometry with top-down electron capture dissociation for characterizing structural transitions of a 17 kDa protein.</a> Journal of the American Chemical Society. 131 (35), 12801-12808 (2009).</li><li>Habibi, Y., Uggowitzer, K. A., Issak, H., Thibodeaux, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insights+into+the+Dynamic+Structural+Properties+of+a+Lanthipeptide+Synthetase+using+Hydrogen-Deuterium+Exchange+Mass+Spectrometry.">Insights into the Dynamic Structural Properties of a Lanthipeptide Synthetase using Hydrogen-Deuterium Exchange Mass Spectrometry.</a> Journal of the American Chemical Society. 141 (37), 14661-14672 (2019).</li><li>Hebling, C. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conformational+analysis+of+membrane+proteins+in+phospholipid+bilayer+nanodiscs+by+hydrogen+exchange+mass+spectrometry.">Conformational analysis of membrane proteins in phospholipid bilayer nanodiscs by hydrogen exchange mass spectrometry.</a> Analytical Chemistry. 82 (13), 5415-5419 (2010).</li><li>Duc, N. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effective+application+of+bicelles+for+conformational+analysis+of+G+protein-coupled+receptors+by+hydrogen/deuterium+exchange+mass+spectrometry.">Effective application of bicelles for conformational analysis of G protein-coupled receptors by hydrogen/deuterium exchange mass spectrometry.</a> Journal of the American Society for Mass Spectrometry. 26 (5), 808-817 (2015).</li><li>Canul-Tec, J. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structure+and+allosteric+inhibition+of+excitatory+amino+acid+transporter+1.">Structure and allosteric inhibition of excitatory amino acid transporter 1.</a> Nature. 544 (7651), 446-451 (2017).</li><li>Reading, E., 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=Interrogating+Membrane+Protein+Conformational+Dynamics+within+Native+Lipid+Compositions.">Interrogating Membrane Protein Conformational Dynamics within Native Lipid Compositions.</a> Angewandte Chemie International Edition. 56 (49), 15654-15657 (2017).</li><li>Hentze, N., Mayer, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analyzing+protein+dynamics+using+hydrogen+exchange+mass+spectrometry.">Analyzing protein dynamics using hydrogen exchange mass spectrometry.</a> Journal of Visualized Experiments. (81), e50839 (2013).</li><li>Lento, 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=Time-resolved+ElectroSpray+Ionization+Hydrogen-deuterium+Exchange+Mass+Spectrometry+for+Studying+Protein+Structure+and+Dynamics.">Time-resolved ElectroSpray Ionization Hydrogen-deuterium Exchange Mass Spectrometry for Studying Protein Structure and Dynamics.</a> Journal of Visualized Experiments. (122), e55464 (2017).</li><li>Schowen, K. B., Schowen, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Solvent+isotope+effects+on+enzyme+systems.">Solvent isotope effects on enzyme systems.</a> Methods in Enzymology. 87, 551-606 (1982).</li><li>Lau, A. M. C., Ahdash, Z., Martens, C., Politis, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deuteros:+software+for+rapid+analysis+and+visualization+of+data+from+differential+hydrogen+deuterium+exchange-mass+spectrometry.">Deuteros: software for rapid analysis and visualization of data from differential hydrogen deuterium exchange-mass spectrometry.</a> Bioinformatics. 35 (7), 3171-3173 (2019).</li><li>Houde, D., Berkowitz, S. A., Engen, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+utility+of+hydrogen/deuterium+exchange+mass+spectrometry+in+biopharmaceutical+comparability+studies.">The utility of hydrogen/deuterium exchange mass spectrometry in biopharmaceutical comparability studies.</a> Journal of Pharmaceutical Sciences. 100 (6), 2071 (2011).</li><li>Burkitt, W., O'Connor, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+the+repeatability+and+reproducibility+of+hydrogen/deuterium+exchange+mass+spectrometry+measurements.">Assessment of the repeatability and reproducibility of hydrogen/deuterium exchange mass spectrometry measurements.</a> Rapid Communications in Mass Spectrometry. 22 (23), 3893-3901 (2008).</li><li>Rob, T., Gill, P. K., Golemi-Kotra, D., Wilson, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+electrospray+ms-coupled+microfluidic+device+for+sub-second+hydrogen/deuterium+exchange+pulse-labelling+reveals+allosteric+effects+in+enzyme+inhibition.">An electrospray ms-coupled microfluidic device for sub-second hydrogen/deuterium exchange pulse-labelling reveals allosteric effects in enzyme inhibition.</a> Lab on a Chip. 13, 2528-2532 (2013).</li></ol>

Nous n’avons rien à divulguer.

Le flux de travail HDX-MS présenté dans ce protocole fournit une plate-forme remarquablement robuste pour cartographier la distribution spatiale des éléments structurellement dynamiques dans les protéines et pour étudier comment ces dynamiques changent en réponse à la perturbation (liaison ligand, mutagenèse enzymatique, etc.). HDX-MS présente plusieurs avantages distincts par rapport à d’autres approches de biologie structurelle qui sont couramment utilisées pour étudier la dynamique conformationnelle. Pl...

Les protéines sont des molécules structurellement dynamiques qui échantillonnent différentes conformations sur des échelles de temps allant des vibrations des liaisons femtosecondes aux réarrangements de domaines protéiques entiers qui peuvent se produire sur plusieurs secondes1. Ces fluctuations conformationnelles sont souvent des aspects critiques de la fonction enzymatique/protéique. Par exemple, les changements conformationnels induits par la liaison ligand sont souvent d’une importance cruciale pour moduler la fonction enzymatique, soit en organisant les résidus actifs du site nécessaires à la catalyse, en définissant les sites de liaison du substrat dans les mécanismes cinétiques séquentiels, en protégeant les intermédiaires réactifs de l’environnement, soit en modulant la fonction enzymatique par l’intermédiaire de réseaux allotériques. Des études récentes ont également montré que la dynamique conformationnelle peut être conservée tout au long de l’évolution et que les perturbations des mouvements moléculaires conservés peuvent être corrélées avec des changements dans la spécificité du substrat et l’émergence de nouvelles fonctions enzymatiques2,3.
Ces dernières années, la spectrométrie de masse d’échange hydrogène-deutérium (HDX-MS) est rapidement apparue comme une technique puissante pour sonder la façon dont les paysages conformationnels protéiques réagissent aux perturbations telles que la liaison ligand ou la mutagenèse4,5,6,7. Dans une expérience typique de HDX-MS (figure 1), une protéine d’intérêt est placée dans le tampon préparé dans D2O, ce qui déclenche le remplacement des protons échangeables de solvants par deutérium. Le taux de change de l’amide moiety des liaisons peptidiques dépend fortement du pH, de la séquence locale d’acides aminés, et de l’environnement structurel local de l’amide8. Les amidons engagés dans des interactions de liaison hydrogène (comme celles présentes dans les α-hélices et les feuilles de β) s’échangent plus lentement que les amides dans les régions non structurées de la protéine qui sont exposées au solvant en vrac. Ainsi, l’étendue de l’absorption de deutérium est un reflet de la structure de l’enzyme. On s’attendrait à ce que les enzymes qui sont conformationally dynamiques, ou qui subissent des transitions structurelles sur la liaison ligand, produisent une réponse mesurable de HDX.
La base mécaniste du taux de change lent d’un amide structuré est indiquée dans la figure 25,8,9. Pour subir le HDX, la région structurée doit d’abord échantillonner transitoirement une conformation dépliée, de sorte que les molécules solvantes qui catalysent l’échange HDX via un mécanisme chimique acide/de base spécifique, aient accès à l’amide échangeable. En fin de compte, les magnitudes relatives du taux de change chimique (kchem) et les taux de pliage et de refolding (kouvert et kfermer) déterminer le taux HDX mesuré dans l’expérience5,8. De ce modèle cinétique simple, il est clair que l’étendue de l’absorption de deutérium reflétera la dynamique conformationnelle sous-jacente (telle que définie par kouvert et kfermer). La plupart des expériences HDX-MS sont réalisées dans un flux de travail ascendant où, suite à la réaction d’échange, la protéine d’intérêt est digérée en peptides et l’absorption de deutérium par chaque peptide est mesurée comme une augmentation de la masse7. De cette façon, HDX-MS permet de cartographier les perturbations de la dynamique conformationnelle des enzymes à l’échelle spatiale locale des peptides, ce qui permet au chercheur d’évaluer comment la perturbation modifie la dynamique dans différentes régions de l’enzyme d’intérêt.
Les avantages de l’approche HDX-MS pour élucider la dynamique structurelle des protéines sont nombreux. Tout d’abord, la méthode peut être effectuée avec de petites quantités de protéines indigènes ou sur des complexes protéiques dans des systèmes à structure quaternaire10. Il n’est même pas nécessaire que la préparation enzymatique utilisée dans l’analyse soit fortement purifiée11,12, tant que le flux de travail HDX-MS ascendant fournit un nombre suffisant de peptides identifiés avec confiance qui couvrent la séquence protéique d’intérêt. En outre, HDX-MS peut fournir des informations sur la dynamique conformationnelle dans des conditions quasi natives sans avoir besoin d’étiquetage protéique spécifique au site comme cela serait utilisé dans les études de fluorescence à moléculeunique 13, et il n’y a pas de limite de taille au complexe protéique ou protéique qui peut être étudié (ce qui rend difficiles des approches telles que la spectroscopie par résonance magnétique nucléaire [NMR])7,14. Enfin, des méthodes HDX-MS résolues dans le temps peuvent être utilisées pour étudier les protéines intrinsèquement désordonnées, qui sont difficiles à étudier avec la cristallographie aux rayons X15,16,17,18. La principale limitation de HDX-MS est que les données sont de faible résolution structurelle. Les données HDX-MS sont utiles pour indiquer où la dynamique conformationnelle évolue et pour révéler des changements conformationnels couplés, mais elles ne fournissent pas souvent beaucoup d’informations sur le mécanisme moléculaire précis qui conduit au changement observé. Les progrès récents dans la combinaison des méthodes de dissociation de capture d’électrons avec les données de protéine HDX-MS se sont révélés prometteurs pour cartographier les sites d’échange aux résidus d’acides aminéssimples 19, mais le suivi des études biochimiques et structurelles sont encore souvent nécessaires pour fournir la clarté aux modèles structurels transmis par les données HDX-MS.
Ci-dessous, un protocole détaillé pour le développement d’un essai HDX-MS est présenté20. Les protocoles de préparation de l’échantillon présentés ci-dessous devraient être généralement applicables à toute protéine qui présente une bonne solubilité dans les tampons aqueux. Des méthodes de préparation d’échantillons plus spécialisées et des workflows HDX-MS sont disponibles pour les protéines que nécessaire en présence de détergent ou de phospholipides21,22,23,24. Les paramètres instrumentaux de collecte de données HDX-MS sont décrits pour un spectromètre de masse quadrupole haute résolution couplé au système de chromatographie liquide. Des données d’une complexité et d’une résolution similaires pourraient être recueillies sur l’un ou l’autre d’un certain nombre de systèmes de spectrométrie de masse chromatographie liquide (LC-MS) disponibles dans le commerce. Des aspects clés du traitement des données à l’aide d’un logiciel disponible dans le commerce sont également fournis. Nous présentons également des lignes directrices pour la collecte et l’analyse des données qui sont conformes aux recommandations formulées par l’ensemble de la communauté HDX-MS12. Le protocole décrit est utilisé pour étudier les propriétés structurelles dynamiques de HalM2, une synthétase lanthipeptide qui catalyse la maturation en plusieurs étapes d’un produit naturel peptidique antimicrobien20. Nous montrons comment HDX-MS peut être utilisé pour révéler les sites de liaison du substrat et les propriétés allostériques qui ont échappé à la caractérisation précédente. Plusieurs autres protocoles sur la protéine HDX-MS ont été publiés ces dernières années25,26. Avec le présent travail, ces contributions antérieures devraient fournir au lecteur une certaine flexibilité dans la conception expérimentale.

<table>
	<tbody>
		<tr>
			<td>Reagents</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>[glu-1]-fibrinopeptide B (Glu-Fib)</td>
			<td>BioBasic</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>0.5 mL Amicon Ultracel 10k centrifugal filtration device (Millipore)</td>
			<td>Milipore Sigma</td>
			<td>UFC501096</td>
			<td></td>
		</tr>
		<tr>
			<td>acetonitrile</td>
			<td>Fisher</td>
			<td>A955-1</td>
			<td></td>
		</tr>
		<tr>
			<td>AMP-PNP</td>
			<td>SIGMA</td>
			<td>A2647-25MG</td>
			<td></td>
		</tr>
		<tr>
			<td>ATP</td>
			<td>SIGMA</td>
			<td>a2383-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>D2O</td>
			<td>ALDRICH</td>
			<td>435767-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>formic acid</td>
			<td>Thermo Fisher</td>
			<td>28905</td>
			<td></td>
		</tr>
		<tr>
			<td>guanidine-HCl</td>
			<td>VWR</td>
			<td>97063-764</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Fisher</td>
			<td>BP310-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium chloride</td>
			<td>SiGMA-Aldrich</td>
			<td>63068-250G</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium chloride</td>
			<td>BioBasic</td>
			<td>PB0440</td>
			<td></td>
		</tr>
		<tr>
			<td>potassium phosphate</td>
			<td>BioBasic</td>
			<td>PB0445</td>
			<td></td>
		</tr>
		<tr>
			<td>TCEP Hydrochloride</td>
			<td>TRC Canada</td>
			<td>T012500</td>
			<td>peptide was synthesized upon request</td>
		</tr>
		<tr>
			<td>Name of Material/ Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr>
			<td>software</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Deuteros</td>
			<td>Andy M C Lau, et al</td>
			<td>version 1.08</td>
			<td></td>
		</tr>
		<tr>
			<td>DynamX</td>
			<td>Waters</td>
			<td>version 3.0</td>
			<td></td>
		</tr>
		<tr>
			<td>MassLynx</td>
			<td>Waters</td>
			<td>version 4.1</td>
			<td></td>
		</tr>
		<tr>
			<td>Protein Lynx 
			Global Server (PLGS)</td>
			<td>Waters</td>
			<td>version 3.0.3</td>
			<td></td>
		</tr>
		<tr>
			<td>PyMOL</td>
			<td>Schr&#246;dinger</td>
			<td>version 2.2.2</td>
			<td></td>
		</tr>
		<tr>
			<td>Name of Material/ Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr>
			<td>Instrument and equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ACQUITY UPLC BEH C18 analytical Column</td>
			<td>Waters</td>
			<td>186002346</td>
			<td></td>
		</tr>
		<tr>
			<td>ACQUITY UPLC BEH C8 VanGuard Pre-column</td>
			<td>Waters</td>
			<td>186003978</td>
			<td></td>
		</tr>
		<tr>
			<td>ACQUITY UPLC M-Class HDX System</td>
			<td>Waters</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>HDX Manager</td>
			<td>Waters</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>microtip pH electrode</td>
			<td>Thermo Fisher</td>
			<td>13-620-291</td>
			<td></td>
		</tr>
		<tr>
			<td>Waters Enzymate BEH column or Pepsin solumn</td>
			<td>Waters</td>
			<td>186007233</td>
			<td></td>
		</tr>
		<tr>
			<td>Waters Synapt G2-Si</td>
			<td>Waters</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

a hydrogen-deuterium exchange mass spectrometry (hdx-ms) platform for investigating peptide biosynthetic enzymes

La spectrométrie de masse d’échange hydrogène-deutérium (HDX-MS) est une méthode puissante pour la caractérisation biophysique des changements conformationnels enzymatiques et des interactions enzyme-substrat. Parmi ses nombreux avantages, HDX-MS ne consomme que de petites quantités de matière, peut être effectuée dans des conditions quasi natives sans avoir besoin d’étiquetage enzymatique/substrat, et peut fournir des informations spatialement résolues sur la dynamique conformationnelle des enzymes, même pour les grandes enzymes et les complexes multiprotéines. La méthode est initiée par la dilution de l’enzyme d’intérêt dans tampon préparé en D2O. Cela déclenche l’échange de protium dans les amides de liaison peptidique (N-H) avec le deutérium (N-D). Aux points de temps d’échange désirés, les aliquots de réaction sont trempés, l’enzyme est protéolysée en peptides, les peptides sont séparés par chromatographie liquide ultra-performante (UPLC), et le changement de masse de chaque peptide (dû à l’échange d’hydrogène contre du deutérium) est enregistré par la SEp. La quantité d’absorption de deutérium par chaque peptide dépend fortement de l’environnement local de liaison hydrogène de ce peptide. Les peptides présents dans les régions très dynamiques de l’échange d’enzymes deutérium très rapidement, tandis que les peptides dérivés de régions bien ordonnées subissent des échanges beaucoup plus lentement. De cette façon, le taux HDX rend compte de la dynamique conformationnelle des enzymes locales. Les perturbations des niveaux d’absorption du deutérium en présence de différents ligands peuvent ensuite être utilisées pour cartographier les sites de liaison ligand, identifier les réseaux allotériques et comprendre le rôle de la dynamique conformationnelle dans la fonction enzymatique. Ici, nous montrons comment nous avons utilisé HDX-MS pour mieux comprendre la biosynthèse d’un type de peptide produits naturels appelés lanthipeptides. Les lanthipeptides sont des peptides génétiquement codés qui sont modifiés post-translationnellement par de grandes enzymes multifonctionnelles et conformationnelles dynamiques qui sont difficiles à étudier avec les approches traditionnelles de biologie structurale. HDX-MS fournit une plate-forme idéale et adaptable pour étudier les propriétés mécanistes de ces types d’enzymes.

Il est nécessaire d’évaluer la qualité de la digestion protéolytique et la reproductibilité du flux de travail pour chaque ensemble d’injections d’échantillons. Ainsi, avant d’effectuer des essais HDX-MS, il est essentiel d’établir des conditions efficaces pour la protéolyse de la protéine d’intérêt, pour la séparation des peptides à l’aide de la chromatographie liquide de phase inverse et de la mobilité des ions de phase gazeuse, et pour la détection des peptides à l’aide de SP. À cette ...

Watch this Scientific Journal Video about A Hydrogen-Deuterium Exchange Mass Spectrometry HDX-MS Platform for Investigating Peptide Biosynthetic Enzymes at JoVE.com

A Hydrogen-Deuterium Exchange Mass Spectrometry HDX-MS Platform for Investigating Peptide Biosynthetic Enzymes

Les synthetases de lanthipeptide catalysent les réactions en plusieurs étapes pendant la biosynthèse des produits naturels peptidiques. Ici, nous décrivons un flux de travail continu, ascendant, de spectrométrie de masse d’échange hydrogène-deutérium (HDX-MS) qui peut être employé pour étudier la dynamique conformationnelle des synthetases de lanthipeptide, aussi bien que d’autres enzymes semblables impliquées dans la biosynthèse de produit naturel de peptide.

Une plate-forme de spectrométrie de masse d’échange hydrogène-deutérium (HDX-MS) pour étudier les enzymes biosynthétiques peptidiques

Hydrogen-deuterium exchange mass spectrometry (HDX-MS) is a powerful method for the biophysical characterization of enzyme conformational changes and ...

a-hydrogen-deuterium-exchange-mass-spectrometry-hdx-ms-platform-for

Research

JoVE Journal

Biochemistry

A Hydrogen-Deuterium Exchange Mass Spectrometry (HDX-MS) Platform for Investigating Peptide Biosynthetic Enzymes

7.8K vues.  McGill University. Les synthetases de lanthipeptide catalysent les réactions en plusieurs étapes pendant la biosynthèse des produits naturels peptidiques. Ici, nous décrivons un flux de travail continu, ascendant, de spectrométrie de masse d’échange hydrogène-deutérium (HDX-MS) qui peut être employé pour étudier la dynamique conformationnelle des synthetases de lanthipeptide, aussi bien que d’autres enzymes semblables impliquées dans la biosynthèse de produit naturel de pep...

Vidéo: A Hydrogen-Deuterium Exchange Mass Spectrometry HDX-MS Platform for Investigating Peptide Biosynthetic Enzymes

Time-resolved ElectroSpray Ionization Hydrogen-deuterium Exchange Mass Spectrometry for Studying Protein Structure and Dynamics

Intrinsically disordered proteins (IDPs) have long been a challenge to structural biologists due to their lack of stable secondary structure elements. Hydrogen-Deuterium Exchange (HDX) measured at rapid time scales is uniquely suited to detect structures and hydrogen bonding networks that are briefly populated, allowing for the characterization of transient conformers in native ensembles. Coupling of HDX to mass spectrometry offers several key advantages, including high sensitivity, low sample consumption and no restriction on protein size. This technique has advanced greatly in the last several decades, including the ability to monitor HDX labeling times on the millisecond time scale. In addition, by incorporating the HDX workflow onto a microfluidic platform housing an acidic protease microreactor, we are able to localize dynamic properties at the peptide level. In this study, Time-Resolved ElectroSpray Ionization Mass Spectrometry (TRESI-MS) coupled to HDX was used to provide a detailed picture of residual structure in the tau protein, as well as the conformational shifts induced upon hyperphosphorylation.

Conformational flexibility plays a critical role in protein function. Herein, we describe the use of time-resolved electrospray ionization mass spectrometry coupled to hydrogen-deuterium exchange for probing the rapid structural changes that drive function in ordered and disordered proteins.

Résolue en temps d&#39;échange hydrogène Ionisation ElectroSpray-deuterium spectrométrie de masse pour l&#39;étude de la structure des protéines et dynamique

Intrinsically disordered proteins (IDPs) have long been a challenge to structural biologists due to their lack of stable secondary structure elements. ...

Recherche

Biochimie

Resolving Affinity Purified Protein Complexes by Blue Native PAGE and Protein Correlation Profiling

Most proteins act in association with others; hence, it is crucial to characterize these functional units in order to fully understand biological processes. Affinity purification coupled to mass spectrometry (AP-MS) has become the method of choice for identifying protein-protein interactions. However, conventional AP-MS studies provide information on protein interactions, but the organizational information is lost. To address this issue, we developed a strategy to unravel the distinct functional assemblies a protein might be involved in, by resolving affinity-purified protein complexes prior to their characterization by mass spectrometry. Protein complexes isolated through affinity purification of a bait protein using an epitope tag and competitive elution are separated through blue native electrophoresis. Comparison of protein migration profiles through correlation profiling using quantitative mass spectrometry allows assignment of interacting proteins to distinct molecular entities. This method is able to resolve protein complexes of close molecular weights that might not be resolved by traditional chromatographic techniques such as gel filtration. With little more work than conventional AP-geLC-MS/MS, we demonstrate this strategy may in many cases be adequate for obtaining protein complex topological information concomitantly to identifying protein interactions.

Here we present protocols for affinity purification of protein complexes and their separation by blue native PAGE, followed by protein correlation profiling using label free quantitative mass spectrometry. This method is useful to resolve interactomes into distinct protein complexes.

Résoudre les complexes protéiques purifiés par affinité de Blue native PAGE et le profilage de corrélation des protéines

Most proteins act in association with others; hence, it is crucial to characterize these functional units in order to fully understand biological ...

Lipid Droplet Isolation for Quantitative Mass Spectrometry Analysis

Lipid droplets are vital to the replication of a variety of different pathogens, most prominently the Hepatitis C Virus (HCV), as the putative site of virion morphogenesis. Quantitative lipid droplet proteome analysis can be used to identify proteins that localize to or are displaced from lipid droplets under conditions such as virus infections. Here, we describe a protocol that has been successfully used to characterize the changes in the lipid droplet proteome following infection with HCV. We use Stable Isotope Labeling with Amino Acids in Cell Culture (SILAC) and thus label the complete proteome of one population of cells with &#34;heavy&#34; amino acids to quantitate the proteins by mass spectrometry. For lipid droplet isolation, the two cell populations (i.e.&#160;HCV-infected/&#34;light&#34; amino acids and uninfected control/&#34;heavy&#34; amino acids) are mixed 1:1 and lysed mechanically in hypotonic buffer. After removing the nuclei and cell debris by low speed centrifugation, lipid droplet-associated proteins are enriched by two subsequent ultracentrifugation steps followed by three washing steps in isotonic buffer. The purity of the lipid droplet fractions is analyzed by western blotting with antibodies recognizing different subcellular compartments. Lipid droplet-associated proteins are then separated by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) followed by Coomassie staining. After tryptic digest, the peptides are quantified by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Using this method, we identified proteins recruited to lipid droplets upon HCV infection that might represent pro- or antiviral host factors. Our method can be applied to a variety of different cells and culture conditions, such as infection with pathogens, environmental stress, or drug treatment.

Lipid droplets are important organelles for the replication of several pathogens, including the Hepatitis C Virus (HCV). We describe a method to isolate lipid droplets for quantitative mass spectrometry of associated proteins; it can be used under a variety of conditions, such as virus infection, environmental stress, or drug treatment.

Isolation Lipid Droplet pour l&#39;analyse quantitative de spectrométrie de masse

Lipid droplets are vital to the replication of a variety of different pathogens, most prominently the Hepatitis C Virus (HCV), as the putative site of ...

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.

Préparation de l’échantillon d’Identification basé sur la spectrométrie de masse des régions de liaison à l’ARN

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

Optimal Preparation of Formalin Fixed Samples for Peptide Based Matrix Assisted Laser Desorption/Ionization Mass Spectrometry Imaging Workflows

The use of matrix-assisted laser desorption/ionization, mass spectrometry imaging (MALDI MSI) has rapidly expanded, since this technique analyzes a host of biomolecules from drugs and lipids to N-glycans. Although various sample preparation techniques exist, detecting peptides from formaldehyde preserved tissues remains one of the most difficult challenges for this type of mass spectrometric analysis. For this reason, we have created and optimized a robust methodology that preserves the spatial information contained within the sample, while eliciting the greatest number of ionizable peptides. We have also aimed to achieve this in a cost effective and simple way, thereby eliminating potential bias or preparation error, which can occur when using automated instrumentation. The end result is a reproducible and inexpensive protocol.

This protocol describes a reproducible and reliable method for the sublimation-based preparation of formalin fixed tissue destined for imaging mass spectrometry.

Une préparation optimale du formol fixé des échantillons à base de peptides Matrix Assisted Laser Desorption/Ionization Mass Spectrometry Imaging Workflows

The use of matrix-assisted laser desorption/ionization, mass spectrometry imaging (MALDI MSI) has rapidly expanded, since this technique analyzes a host ...

Defining Hsp33's Redox-regulated Chaperone Activity and Mapping Conformational Changes on Hsp33 Using Hydrogen-deuterium Exchange Mass Spectrometry

Living organisms regularly need to cope with fluctuating environments during their life cycle, including changes in temperature, pH, the accumulation of reactive oxygen species, and more. These fluctuations can lead to a widespread protein unfolding, aggregation, and cell death. Therefore, cells have evolved a dynamic and stress-specific network of molecular chaperones, which maintain a "healthy" proteome during stress conditions. ATP-independent chaperones constitute one major class of molecular chaperones, which serve as first-line defense molecules, protecting against protein aggregation in a stress-dependent manner. One feature these chaperones have in common is their ability to utilize structural plasticity for their stress-specific activation, recognition, and release of the misfolded client. 
In this paper, we focus on the functional and structural analysis of one such intrinsically disordered chaperone, the bacterial redox-regulated Hsp33, which protects proteins against aggregation during oxidative stress. Here, we present a toolbox of diverse techniques for studying redox-regulated chaperone activity, as well as for mapping conformational changes of the chaperone, underlying its activity. Specifically, we describe a workflow which includes the preparation of fully reduced and fully oxidized proteins, followed by an analysis of the chaperone anti-aggregation activity in vitro using light-scattering, focusing on the degree of the anti-aggregation activity and its kinetics. To overcome frequent outliers accumulated during aggregation assays, we describe the usage of Kfits, a novel graphical tool which allows easy processing of kinetic measurements. This tool can be easily applied to other types of kinetic measurements for removing outliers and fitting kinetic parameters. To correlate the function with the protein structure, we describe the setup and workflow of a structural mass spectrometry technique, hydrogen-deuterium exchange mass spectrometry, that allows the mapping of conformational changes on the chaperone and substrate during different stages of Hsp33 activity. The same methodology can be applied to other protein-protein and protein-ligand interactions.

Defining Hsp33&#039;s Redox-regulated Chaperone Activity and Mapping Conformational Changes on Hsp33 Using Hydrogen-deuterium Exchange Mass Spectrometry

One of the most challenging stress conditions that organisms encounter during their lifetime involves the accumulation of oxidants. During oxidative stress, cells heavily rely on molecular chaperones. Here, we present methods used to investigate the redox-regulated anti-aggregation activity, as well as to monitor structural changes governing the chaperone function using HDX-MS.

Définition d’activité réglementée Redox chaperon de Hsp33 et de cartographie des changements conformationnels sur Hsp33 à l’aide de la spectrométrie de masse d’hydrogène deutérium Exchange

Living organisms regularly need to cope with fluctuating environments during their life cycle, including changes in temperature, pH, the accumulation of ...

Detection of Protein Ubiquitination Sites by Peptide Enrichment and Mass Spectrometry

The posttranslational modification of proteins by the small protein ubiquitin is involved in many cellular events. After tryptic digestion of ubiquitinated proteins, peptides with a diglycine remnant conjugated to the epsilon amino group of lysine (&#39;K-&#949;-diglycine&#39; or simply &#39;diGly&#39;) can be used to track back the original modification site. Efficient immunopurification of diGly peptides combined with sensitive detection by mass spectrometry has resulted in a huge increase in the number of ubiquitination sites identified up to date. We have made several improvements to this workflow, including offline high pH reverse-phase fractionation of peptides prior to the enrichment procedure, and the inclusion of more advanced peptide fragmentation settings in the ion routing multipole. Also, more efficient cleanup of the sample using a filter-based plug in order to retain the antibody beads results in a greater specificity for diGly peptides. These improvements result in the routine detection of more than 23,000 diGly peptides from human cervical cancer cells (HeLa) cell lysates upon proteasome inhibition in the cell. We show the efficacy of this strategy for in-depth analysis of the ubiquitinome profiles of several different cell types and of in vivo samples, such as brain tissue. This study presents an original addition to the toolbox for protein ubiquitination analysis to uncover the deep cellular ubiquitinome.

We present a method for the purification, detection, and identification of diGly peptides that originate from ubiquitinated proteins from complex biological samples. The presented method is reproducible, robust, and outperforms published methods with respect to the level of depth of the ubiquitinome analysis.

Détection des sites d’ubiquitination des protéines par l’enrichissement du peptide et la spectrométrie de masse

The posttranslational modification of proteins by the small protein ubiquitin is involved in many cellular events. After tryptic digestion of ...

Nitropeptide Profiling and Identification Illustrated by Angiotensin II

Protein nitration is one of the most important post-translational modifications (PTM) on tyrosine residues and it can be induced by chemical actions of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in eukaryotic cells. Precise identification of nitration sites on proteins is crucial for understanding the physiological and pathological processes related to protein nitration, such as inflammation, aging, and cancer. Since the nitrated proteins are of low abundance in cells even under induced conditions, no universal and efficient methods have been developed for the profiling and identification of protein nitration sites. Here we describe a protocol for nitropeptide enrichment by using a chemical reduction reaction and biotin labeling, followed by high resolution mass spectrometry. In our method, nitropeptide derivatives can be identified with high accuracy. Our method exhibits two advantages compared to the previously reported methods. First, dimethyl labeling is used to block the primary amine on nitropeptides, which can be used to generate quantitative results. Second, a disulfide bond containing NHS-biotin reagent is used for the enrichment, which can be further reduced and alkylated to enhance the detection signal on a mass spectrometer. This protocol has been successfully applied to the model peptide Angiotensin II in the current paper.

Proteomic profiling of tyrosine-nitrated proteins has been a challenging technique due to the low abundance of the 3-nitrotyrosine modification. Here we describe a novel approach for nitropeptide enrichment and profiling by using Angiotensin II as the model. This method can be extended for other in vitro or in vivo systems.

Profilage et identification de Nitropeptide illustrépar Angiotensin II

Protein nitration is one of the most important post-translational modifications (PTM) on tyrosine residues and it can be induced by chemical actions of ...

A Plasma Sample Preparation for Mass Spectrometry using an Automated Workstation

Sample preparation for mass spectrometry analysis in proteomics requires enzymatic cleavage of proteins into a peptide mixture. This process involves numerous incubation and liquid transfer steps in order to achieve denaturation, reduction, alkylation, and cleavage. Adapting this workflow onto an automated workstation can increase efficiency and reduce coefficients of variance, thereby providing more reliable data for statistical comparisons between sample types. We previously described an automated proteomic sample preparation workflow1. Here, we report the development of a more efficient and better controlled workflow with the following advantages: 1) The number of liquid transfer steps is reduced from nine to six by combining reagents; 2) Pipetting time is reduced by selective tip pipetting using a 96-position pipetting head with multiple channels; 3) Potential throughput is increased by the availability of up to 45 deck positions; 4) Complete enclosure of the system provides improved temperature and environmental control and reduces the potential for contamination of samples or reagents; and 5) The addition of stable isotope labeled peptides, as well as &#946;-galactosidase protein, to each sample makes monitoring and quality control possible throughout the entire process. These hardware and process improvements provide good reproducibility and improve intra-assay and inter-assay precision (CV of less than 20%) for LC-MS based protein and peptide quantification. The entire workflow for digesting 96 samples in a 96-well plate can be completed in approximately 5 hours.

Here, we present an automated plasma protein digestion method for mass spectrometry-based quantitative proteomic analysis. In this protocol, the liquid transferring and incubation steps for protein denaturation, reduction, alkylation, and trypsin digestion reactions are streamlined and automated. It takes approximately five hours to prepare a 96-well plate with desired precision.

Préparation d’un échantillon de plasma pour la spectrométrie de masse à l’aide d’un poste de travail automatisé

Sample preparation for mass spectrometry analysis in proteomics requires enzymatic cleavage of proteins into a peptide mixture. This process involves ...

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.

Préparation d’échantillons pour la spectrométrie de masse d’ionisation de l’électrospray de sonde

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