Chemical tagging of amino acids is an important tool in proteomics analysis, and has been used to introduce isotope labels and mass defect labels into proteolytic peptides by derivatization of cysteine or lysine residues. Here, we present a new reagent with chemical specificity for tryptophan residues. Previously, 2-nitrobenzenesulfenyl chloride has been used as a highly specific reagent for labeling tryptophan residues. We show that this tag undergoes UV dissociation during matrix assisted laser desorption/ionization (MALDI). The multiplicity of photofragments increases the difficulty of characterizing the derivatization products. To overcome this problem, we have synthesized a new reagent, 2-(trifluoromethyl)benzenesulfenyl chloride, which is shown to react quantitatively with tryptophan in peptides and proteins. Most significantly, it exhibits high photostability in MALDI-Fourier transform mass spectrometry analyses.
HamdanM. and RighettiP.G., “Modern strategies for protein quantification in proteome analysis: Advantages and limitations”, Mass Spectrom. Rev.21, 287 (2002). doi: 10.1002/mas.10032
2.
LeitnerA. and LindnerW., “Current chemical tagging strategies for proteome analysis by mass spectrometry”, J. Chromatogr. B813, 1 (2004).
3.
GygiS.P.RistB.GerberS.A.TurecekF.GelbM.H. and AebersoldR., “Quantitative analysis of complex protein mixtures using isotope-coded affinity tags”, Nat. Biotechnol.17, 994 (1999). doi: 10.1038/13690
4.
HernandezH.NiehauserS.BoltzS.A.GawandiV.PhillipsR.S. and AmsterI.J., “Mass defect labeling of cysteine for improving peptide assignment in shotgun proteomic analyses”, Anal. Chem.78, 3417 (2006). doi: 10.1021/ac0600407
5.
HaleJ.E.ButlerJ.P.KniermanM.D. and BeckerG.W., “Increased sensitivity of tryptic peptide detection by MALDI-TOF mass spectrometry is achieved by conversion of lysine to homoarginine”, Anal. Biochem.287, 110 (2000). doi: 10.1006/abio.2000.4834
6.
BeardsleyR.L.KartyJ.A. and ReillyJ.P., “Enhancing the intensities of lysine-terminated tryptic peptide ions in matrix-assisted laser desorption/ionization mass spectrometry”, Rapid Commun. Mass Spectrom.14, 2147 (2000). doi: 10.1002/1097-0231(20001215)14:23<2147::AID-RCM145>3.0.CO;2-M
7.
BranciaF.L.OliverS.G. and GaskellS.J., “Improved matrix-assisted laser desorption/ionization mass spectrometric analysis of tryptic hydrolysates of proteins following guanidination of lysine-containing peptides”, Rapid Commun. Mass Spectrom.14, 2070 (2000). doi: 10.1002/1097-0231(20001115)14:21<2070::AID-RCM133>3.0.CO;2-G
8.
KeoughT.LaceyM.P. and YoungquistR.S., “Derivatization procedures to facilitate de novo sequencing of lysine-terminated tryptic peptides using postsource decay matrix-assisted laser desorption/ionization mass spectrometry”, Rapid Commun. Mass Spectrom.14, 2348 (2000). doi: 10.1002/1097-0231(20001230)14:24<2348::AID-RCM175>3.0.CO;2-8
9.
CagneyG. and EmiliA., “De novo peptide sequencing and quantitative profiling of complex protein mixtures using mass-coded abundance tagging”, Nat. Biotechnol.20, 163 (2002). doi: 10.1038/nbt0202-163
10.
CreightonT.E., Proteins: Structures and Molecular Properties, 2nd Edn.W.H. Freeman and Company, New York, USA, (1993).
11.
WeilL.JamesS. and BuchertA.R., “Photooxidation of Crystalline Chymotrypsin in the Presence of Methylene Blue Arch”, Biochem. Biophys.46, 266 (1953). doi: 10.1016/0003-9861(53)90200-8
PrevieroA.ColettiM.A. and GalzignaL., “Modification of Tryptophan Residues in Trypsin Alpha-Chymotrypsin + Pep sinogen”, Biochem. Biophys. Res. Commun.16, 195 (1964). doi: 10.1016/0006-291X(64)90360-2
14.
PatchornikA.LawsonW.B. and WitkopB., “Selective Cleavage of Peptide Bonds. 2. The Tryptophyl Peptide Bond and the Cleavage of Glucagon”, J. Am. Chem. Soc.80, 4747 (1958). doi: 10.1021/ja01550a090
15.
KoshlandD.E.KarkhanisY.D.LathamH.G., “Environmentally-Sensitive Reagent with Selectivity for Tryptophan Residue in Proteins”, J. Am. Chem. Soc.86, 1448 (1964). doi: 10.1021/ja01061a045
16.
ScoffoneE.FontanaA. and RocchiR., “Selective Modification of Tryptophan Residue in Peptides and Proteins Using Sulfenyl Halides”, Biochem. Biophys. Res. Commun.25, 170 (1966). doi: 10.1016/0006-291X(66)90575-4
17.
ScoffoneE.FontanaA. and RocchiR., “Sulfenyl Halides as Modifying Reagents for Polypeptides and Proteins. I. Modification of Tryptophan Residues”, Biochemistry7, 971 (1968). doi: 10.1021/bi00843a014
18.
FontanaA. and ScoffoneE., “Sulfenyl Halides as Modifying Reagents for Polypeptides and Proteins”, Methods Enzymol.25, 482 (1972).
19.
FontanaA.VeroneseF.M. and BoccuE., “Reaction of Sulfenyl Halides with Cytochrome—Novel Method for Heme Cleavage”, Febs Lett.32, 135 (1973). doi: 10.1016/0014-5793(73)80756-2
20.
TanakaS.MohriN.KiharaH. and OhnoM., “Selective Separation of Tryptophan-Containing Peptides Via Hydrophobic Modification with 2-Nitro-4-Carboxy-Phenylsulfenyl Chloride”, J. Biochem.97, 1377 (1985).
21.
KuyamaH.WatanabeM.TodaC.AndoE.TanakaK. and NishimuraO., “An approach to quantitative proteome analysis by labeling tryptophan residues”, Rapid Commun. Mass Spectrom.17, 1642 (2003). doi: 10.1002/rcm.1100
22.
BandgarB.P.SadavarteV.S.ShindeS.D. and KambleV.T., “Rapid Synthesis of Thiophenols under Mild and Non-Aqueous Conditions”, Sulfur Letters24, 123 (2000).
23.
MarshallA.ClarkA.JenningsR.LedinghamK.W.D.SanderJ. and SinghalR.P., “Laser-Induced Dissociation, Ionization and Fragmentation Processes in Nitroaromatic Molecules”, Int. J. Mass Spectrom. Ion Processes116, 143 (1992). doi: 10.1016/0168-1176(92)80124-J
24.
KosmidisC.LedinghamK.W.D.ClarkA.MarshallA.JenningsR.SanderJ. and SinghalR.P., “On the Dissociation Pathways of Nitrobenzene”, Int. J. Mass Spectrom. Ion Processes135, 229 (1994). doi: 10.1016/0168-1176(94)04008-7
25.
LowW.KangJ.DiGruccioM.KirbyD.PerrinM. and FischerW. H., “MALDI-MS analysis of peptides modified with photolabile arylazido groups”, J. Am. Soc. Mass Spectrom.15, 1156 (2004). doi: 10.1016/j.jasms.2004.04.023
