この研究は、カナダの自然科学工学研究評議会、ケベック自然とテクノロジー、カナダイノベーション財団、マギル大学のスタートアップ資金によって支援されました。

<ol>
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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. 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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. 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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. 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開示するものは何もありません。

このプロトコルで提示されるHDX-MSワークフローは、タンパク質中の構造的に動的な要素の空間分布をマッピングし、これらのダイナミクスが摂動(リガンド結合、酵素変異生成など)にどのように変化するかを調査するための非常に堅牢なプラットフォームを提供します。HDX-MSは、立体構造ダイナミクスの調査に一般的に使用される他の構造生物学アプローチに対して、いくつかの明確な利点?...

タンパク質は、フェムト秒スケールの結合振動から、何秒間にわたって起こり得るタンパク質ドメイン全体の再配置に至るまで、時間スケールで異なる立体構造をサンプリングする構造的に動的な分子である1。これらの立体構造変動は、しばしば酵素/タンパク質機能の重要な側面です。例えば、リガンド結合によって誘導される立体構造変化は、触媒に必要な活性部位残基を組織し、連続的な運動機構で基質結合部位を定義し、反応性中間体を環境から遮蔽するか、またはアロステリックネットワークを介して酵素機能を調節することによって、酵素機能を調節するために非常に重要である。最近の研究では、立体構造ダイナミクスは進化を通して保存することができ、保存された分子運動への摂動は基質特異性の変化および新しい酵素機能の出現と相関することができることを示している2,3。
近年、水素-重水素交換質量分析(HDX-MS)は、リガンド結合や変異形成などの摂動にタンパク質の立体構造の景観がどのように応答するかを調査する強力な技術として急速に出現している4、5、6、7。典型的なHDX-MS実験(図1)では、目的のタンパク質をD2Oで調製したバッファーに入れ、溶媒交換可能なプロトンを重水素に置換する。ペプチド結合のアミド部分の交換速度は、pH、局所アミノ酸配列、およびアミド8の局所構造環境に強く依存する。水素結合相互作用に関与しているアミド(αヘリックスやβシートに存在するものなど)は、バルク溶媒にさらされているタンパク質の非構造化領域のアミドよりもゆっくりと交換します。したがって、重水素の取り込みの程度は、酵素の構造の反映である。立体構造が動的な酵素、またはリガンド結合時に構造的な転移を起す酵素は、測定可能なHDX応答をもたらすと予想されるであろう。
構造化アミドの遅い為替レートの機械化基準を図25,8,9に示します。HDXを受けるためには、特定の酸/塩基化学機構を介してHDX交換を触媒する溶媒分子が交換可能なアミドにアクセスできるように、まず一時的に展開された立体構造をサンプリングする必要があります。最終的に、化学為替レート(kchem)と折り畳み速度(kオープンおよびkクローズ)の相対マグニチュードは、実験5,8で測定されたHDXレートを決定する。この単純な運動モデルから、重水素取り込みの程度が基礎となる立体ダイナミクス(kopenとk close)を反映することは明らかです。ほとんどのHDX-MS実験は、交換反応に続いて、目的のタンパク質がペプチドに消化され、各ペプチドによる重水素取り込みが質量7の増加として測定されるボトムアップワークフローで行われる。このように、HDX-MSは、酵素立体構造ダイナミクスへの摂動をペプチドの局所空間スケールにマッピングすることを可能にし、摂動が目的の酵素の異なる領域のダイナミクスをどのように変化させるかを評価することを可能にする。
タンパク質構造力学を解明するためのHDX-MSアプローチの利点は数多くあります。まず、この方法は、第四級構造10の系において少量の天然タンパク質またはタンパク質複合体に対して実施することができる。ボトムアップHDX-MSワークフローが目的のタンパク質配列をカバーする十分な数の確実に同定されたペプチドを提供する限り、アッセイに使用される酵素調製物が高度に精製される11,12である必要さえありません。さらに、HDX-MSは、単一分子蛍光研究13で用いられるような部位特異的タンパク質標識を必要とせずに、近い在来条件下での立体構造ダイナミクスに関する情報を提供することができ、また、調査できるタンパク質またはタンパク質複合体(核磁気共鳴[NMR]分光法などのアプローチを困難にする)にサイズ制限はない。最後に、時間分解HDX-MS法は、X線結晶学15、16、17、18で研究することが困難である本質的に障害を持つタンパク質を研究するために使用することができる。HDX-MSの主な制限は、データが低い構造分解能であるということです。HDX-MSデータは、立体ダイナミクスが変化している場所を指し示し、結合された立体構造の変化を明らかにするのに役立ちますが、観察された変化を駆動する正確な分子メカニズムに関する多くの洞察を提供することはあまりありません。電子捕獲解離法とタンパク質HDX-MSデータの組み合わせにおける最近の進歩は、交換部位を単一アミノ酸残基19にマッピングする約束を示しているが、HDX-MSデータによって転送される構造モデルを明確にするために、生化学的および構造的研究をフォローアップすることが依然としてしばしば必要である。
以下、HDX-MSアッセイの開発のための詳細なプロトコルが20を提示される。以下に示すサンプル調製プロトコルは、一般的に、水性バッファーに良好な溶解性を示す任意のタンパク質に適用できる必要があります。より特殊なサンプル調製方法およびHDX-MSワークフローは、洗浄剤またはリン脂質21、22、23、24の存在下でのアッセイが必要以上にタンパク質に対して利用可能である。HDX-MS データ収集のインストゥルメンタル設定は、液体クロマトグラフィー システムに結合された高分解能の四重極時間質量分析計について説明されています。同様の複雑性と分解能のデータは、市販の液体クロマトグラフィー質量分析(LC-MS)システムの中から収集できます。市販のソフトウェアパッケージを用いたデータ処理の重要な側面も提供される。また、より広範な HDX-MS コミュニティ12の推奨事項と一致するデータ収集と分析のガイドラインも示します。本記載のプロトコルは、HalM2の動的構造特性を研究するために用いられる、抗菌ペプチド天然物20の多段階成熟を触媒するランチペプチド合成酵素である。我々は、HDX-MSを用いて、これまでの特徴付けが排除された基質結合部位およびアロステリック特性を明らかにする方法を示す。タンパク質HDX-MSに関する他のいくつかのプロトコルが近年25,26で公開されている。現在の作業と共に、これらの以前の貢献は、読者に実験計画のいくつかの柔軟性を提供する必要があります。

<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

水素重水素交換質量分析(HDX-MS)は、酵素の立体構造変化と酵素基質相互作用の生物物理特性解析に対する強力な方法です。その多くの利点の中で、HDX-MSは少量の材料しか消費せず、酵素/基質標識を必要とせずに近い天然条件下で行うことができるので、大きな酵素および多タンパク質複合体に対しても酵素立体構造ダイナミクスに関する空間的に解決された情報を提供することができます。この方法は、D2Oで調製した緩衝液への目的の酵素の希釈によって開始される。これは、重水素(N-D)とのペプチド結合アミド(N-H)中のプロチウムの交換を引き起こす。所望の交換時点で、反応アリコートがクエンチされ、酵素がペプチドにタンパク質化され、ペプチドが超高性能液体クロマトグラフィー(UPLC)によって分離され、各ペプチドの質量の変化(重水素に対する水素交換による)がMSによって記録される。各ペプチドによる重水素の取り込みの量は、そのペプチドの局所水素結合環境に強く依存する。酵素交換重水素の非常に動的な領域に存在するペプチドは非常に迅速に存在するのに対し、整然とした領域に由来するペプチドは、はるかにゆっくりと交換を受ける。このようにして、HDXレートは局所的な酵素立体構造ダイナミクスについて報告する。異なるリガンドの存在下で重水素の取り込みレベルへの摂動は、リガンド結合部位をマッピングし、アロステリックネットワークを同定し、酵素機能における立体構造ダイナミクスの役割を理解するために使用することができる。ここでは、ランチペプチドと呼ばれるペプチド天然物の生合成をより深く理解するためにHDX-MSを使用した方法を説明します。ランチペプチドは、従来の構造生物学のアプローチでは研究が困難な大規模で多機能な構造動的酵素によって翻訳後に修飾される遺伝的にコードされたペプチドです。HDX-MSは、これらのタイプの酵素の機械特性を調査するための理想的で適応可能なプラットフォームを提供します。

タンパク質分解消化の品質とサンプル注射の各セットのワークフローの再現性を評価する必要があります。したがって、HDX-MSアッセイを行う前に、目的のタンパク質のタンパク質分解、逆相液体クロマトグラフィーと気相イオン移動度を用いたペプチドの分離、およびMSを用いたペプチドの検出に有効な条件を確立することが不可欠です。この目的のために、対象となるタンパク質(重水素の?...

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

ランチペプチド合成酵素は、ペプチド天然物の生合成中に多段階反応を触媒する。ここでは、ランチペプチド合成酵素の立体ダイナミクス、ならびにペプチド天然物生合成に関与する他の同様の酵素を研究するために使用できる、連続的なボトムアップ、水素重水素交換質量分析(HDX-MS)ワークフローについて述べています。

ペプチド生合成酵素を調べた水素重水素交換質量分析(HDX-MS)プラットフォーム

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 ビュー.  McGill University. ランチペプチド合成酵素は、ペプチド天然物の生合成中に多段階反応を触媒する。ここでは、ランチペプチド合成酵素の立体ダイナミクス、ならびにペプチド天然物生合成に関与する他の同様の酵素を研究するために使用できる、連続的なボトムアップ、水素重水素交換質量分析(HDX-MS)ワークフローについて述べています。

ビデオ: 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.

時間分解エレクトロスプレーイオン化水素 - 重水素交換質量分析タンパク質の構造とダイナミクスを学ぶために

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

生化学

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.

ブルーネイティブPAGEおよびタンパク質相関プロファイリングによってアフィニティー精製タンパク質複合体の解決

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.

定量的質量分析のための脂肪滴の分離

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.

質量分析を用いた識別 RNA 結合領域のための試料作製

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.

ペプチド ベースのマトリックスのためにサンプルを固定ホルマリンの最適な準備支援レーザー脱離イオン化質量分析イメージング ワークフロー

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.

Hsp33 の酸化還元規制シャペロン活性を定義および水素重水素交換質量分析法による Hsp33 の構造変化をマッピング

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.

ペプチド濃縮と質量分析によるタンパク質ユビキチン化部位の検出

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.

アンジオテンシンIIによるニトロペプチドプロファイリングと同定

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.

自動ワークステーションを用いた質量分析のためのプラズマサンプル調製

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.

プローブエレクトロスプレーイオン化質量分析のためのサンプル調製

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