Gas-Phase Ionization/Desolvation Processes and Their Effect on Protein Charge State Distribution under Matrix-Assisted Laser Desorption/Ionization Conditions
Restricted accessResearch articleFirst published online December, 2006
Gas-Phase Ionization/Desolvation Processes and Their Effect on Protein Charge State Distribution under Matrix-Assisted Laser Desorption/Ionization Conditions
The charge state distribution of proteins was studied as a function of experimental conditions, to improve the understanding of the matrix-assisted laser desorption/ionization (MALDI) mechanisms. The relative abundances of the multiply-charged ions appear to be a function of the matrix chosen, the laser fluence and the matrix-to-analyte molar ratio. A correlation is found between the matrix proton affinity and the yield of singly- versus multiply-charged ions. These results are in good agreement with a model in which gas-phase intracluster reactions play a significant role in analyte ion formation. A new model for endothermic desolvation processes in ultraviolet/MALDI is presented and discussed. It is based upon the existence of highly-charged precursor clusters and, complementary to the ion survivor model of Karas et al., assumes that two energy-dependent processes exist: (i) a soft desolvation involving consecutive losses of neutral matrix molecules, leading to a multiply-charged analyte and (ii) hard desolvation leading to a low charge state analyte, by consecutive losses of charged matrix molecules. These desolvations pathways are discussed in terms of kinetically limited processes. The efficiency of the two competitive desolvation processes seems related to the internal energy carried away by clusters during ablation.
BeavisR.C.ChaitB.T., “Factors affecting the ultraviolet laser desorption of proteins”, Rapid Commun. Mass Spectrom.3, 233 (1989). doi: 10.1002/rcm.1290030708
2.
HillenkampF.KarasM.BeavisR.C.ChaitB.T., “Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry of Biopolymers”, Anal. Chem.64, 1193 (1991).
3.
SimmonsT.A.LimbachP.A., “Influence of Co-matrix Proton Affinity on Oligonucleotide Ion Stability in Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry”, J. Am. Soc. Mass Spectrom.9, 668 (1998). doi: 10.1016/S1044-0305(98)00049-X
4.
HarveyD.J., “Matrix-assisted laser desorption/ionization mass spectrometry of carbohydrates”, Mass Spectrom. Rev.18, 349 (1999). doi: 10.1002/(SICI)1098-2787(1999)18:6<349::AID-MAS1>3.0.CO;2-H
5.
RäderH.J.SchreppW., “MALDI-TOF mass spectrometry in the analysis of synthetic polymers”, Acta Polymer49, 272 (1998). doi: 10.1002/(SICI)1521-4044(199806)49:6<272::AID-APOL272>3.0.CO;2-1
6.
DreisewerdK., “The Desorption Process in MALDI”, Chem. Rev.103, 395 (2003). doi: 10.1021/cr010375i
7.
PaltaufG.DyerP.E., “Photomechanical Processes and Effects in Ablation”, Chem. Rev.103, 487 (2003). doi: 10.1021/cr010436c
8.
BogartsA.ChenZ.GijbelsR.VertesA., “Laser ablation for analytical sampling: What can we learn from-modeling?”, Spectrochim. Acta B58, 1867 (2003). doi: 10.1016/j.sab.2003.08.004
9.
KnochenmussR.ZenobiR., “MALDI Ionization: The Role of In-Plume Processes”, Chem. Rev.103, 441 (2003). doi: 10.1021/cr0103773
10.
ChenY.VertesA., “Pumping Rate and Surface Morphology Dependence of Ionization Processes in Matrix-Assisted Laser Desorption Ionization”, J. Phys. Chem. A107, 9754 (2003). doi: 10.1021/jp035844u
11.
LandC.M.KinselG.R., “Investigation of the mechanism of intracluster proton transfer from sinapinic acid to biomolecular analytes”, J. Am. Soc. Mass Spectrom.9, 1060 (1998). doi: 10.1016/S1044-0305(98)00070-1
12.
WestanA.Huth-FehreT.DemirevP.BielawskiJ.MedinaN.SundqvistB.U.R.KarasM., “Matrix-assisted laser desorption/ionization: Dependence of the ion yield on the laser beam incidence angle”, Rapid Commun. Mass Spectrom.8, 388 (1994). doi: 10.1002/rcm.1290080510
13.
RiahiK.BolbachG.BrunotA.BretonF.SpiroM.BlaisJ.C., “Influence of laser focusing in matrix-assisted laser desorption/ionization”, Rapid Commun. Mass Spectrom.8, 242 (1994). doi: 10.1002/rcm.1290080304
14.
ZhouJ.LeeT.D., “Charge State Distribution Shifting of Protein Ions Observed in Matrix-Assisted Laser Desorption Ionization Mass Spectrometry”, J. Am. Soc. Mass Spectrom.6, 1183 (1995). doi: 10.1016/1044-0305(95)00578-1
15.
ZhongF.ZhaoS., “A study of factors influencing the formation of singly charged oligomers and multiply charged monomers by matrix-assisted laser desorption/ionization mass spectrometry”, Rapid Commun. Mass Spectrom.9, 570 (1995). doi: 10.1002/rcm.1290090705
16.
BencsuraA.NaveleV.SadeghiM.VertesA., “Matrix-Guest Energy Transfer in Matrix-assisted Laser Desorption”, Rapid Commun. Mass Spectrom.11, 679 (1997). doi: 10.1002/(SICI)1097-0231(199704)11:6<679::AID-RCM840>3.0.CO;2-Z
17.
ZighileiL.V.KodaliP.B.S.GarrisonB.J., “On the threshold behavior in laser ablation of organic solids”, Chem. Phys. Lett.276, 269 (1997). doi: 10.1016/S0009-2614(97)00808-7
18.
KnochenmussR.ZhigileiL.V., “Molecular Dynamics Model of Ultraviolet Matrix-Assisted Laser Desorption/Ionization Including Ionization Processes”, J. Chem. Phys. B109, 22947 (2005). doi: 10.1021/jp052945e
19.
ChanT.W.D.ColburnA.W.DerrickP.J.GardinerD.J.BowdenM., “Suppression of matrix ions in ultraviolet laser desorption: Scanning electron microscopy and raman spectroscopy of the solid samples”, Org. Mass Spectrom.27, 188 (1992). doi: 10.1002/oms.1210270307
20.
KnochenmussR.VertesA., “Time-delayed 2-Pulse Studies of MALDI Matrix Ionization Mechanisms”, J. Phys. Chem. B104, 5406 (2000). doi: 10.1021/jp000494m
21.
KnochenmussR.ZenobiR., “Ion formation in MALDI mass spectrometry”, Mass Spectrom. Rev.17, 337 (1998). doi: 10.1002/(SICI)1098-2787(1998)17:5<337::AID-MAS2 >3.0.CO;2-S
22.
KarasM.GlückmannM.ShaferJ., “Ionization in matrix-assisted laser desorption/ionization: Singly charged molecular ions are the lucky survivors”, J. Mass Spectrom.35, 1 (2000). doi: 10.1002/(SICI)1096-9888(200001)35:1<1::AID-JMS904>3.0.CO;2-0
23.
HornefferV.DreiswerdK.LüdemannH.C.HillenkampF.LägeM.StrupatK., “Is the incorporation of analytes into matrix crystals a prerequisite for matrix-assisted laser desorption/ionization mass spectrometry? A study of five positional isomers of dihydroxybenzoic acid”, Int. J. Mass Spectom185–187, 859 (1999). doi: 10.1016/S1387-3806(98)14218-5
24.
WestmanA.Huth-FehreT.BielawskiJ.SundqvistB.U.R., “Sample morphology effects in matrix-assisted laser desorption/ionization mass spectrometry of proteins”, J. Mass Spectrom.30, 206 (1995). doi: 10.1002/jms.1190300131
25.
KampmeierJ.DreiswerdK.SchürenbergM.StrupatK.KarasM., “Investigations of 2,5-DHB and succinic acid as matrices for IR and UV MALDI. Part: I UV and IR laser ablation in the MALDI process”, Int. J. Mass Spectrom. Ion Processes169/170, 31 (1997). doi: 10.1016/S0168-1176(97)00224-3
26.
StrupatK.KampmeierJ.HornefferV., “Investigations of 2,5-DHB and succinic acid as matrices for UV and IR MALDI. Part II: Crystallographic and mass spectrometric analysis”, Int. J. Mass Spectrom. Ion Processes169/170, 43 (1997). doi: 10.1016/S0168-1176(97)00225-5
27.
FournierI.BeavisR.C.BlaisJ.C.TabetJ.C.BolbachG., “Hysteresis effects observed in MALDI using oriented, protein-doped matrix crystals”, Int. J. Mass Spectrom. Ion Processes169/170, 19 (1997). doi: 10.1016/S0168-1176(97)00212-7
PuretzkyA.A.GeoheganD.B., “Gas-phase diagnostics and LIF-imaging of 3-hydroxypicolinic acid maldi-matrix plumes”, Chem. Phys. Lett.286, 425 (1998). doi: 10.1016/S0009-2614(98)00013-X
30.
BokelmannV.SpenglerB.KaufmannR., Eur. Mass Spectrom1, 81 (1995).
31.
GluckmannM.KarasM., “The initial ion velocity and its dependence on matrix, analyte and preparation method in ultraviolet matrix-assisted laser desorption/ionization”, J. Mass Spectrom.34, 467 (1999). doi: 10.1002/(SICI)1096-9888(199905)34:5<467::AID-JMS809>3.0.CO;2-8
32.
KinselG.R.Gimon-KinselM.E.GilligK.J.RussellD.H., “Investigation of the dynamics of matrix-assisted laser desorption/ionization ion formation using an electrostatic analyzer/time-of-flight mass spectrometer”, J. Mass Spectrom.34, 684 (1999). doi: 10.1002/(SICI)1096-9888(199906)34:6<684::AID-JMS822>3.0.CO;2-O
33.
KnochenmussR., “A quantitative model of ultraviolet matrix-assisted laser desorption/ionization”, J. Mass Spectrom.37, 867 (2002).
34.
KnochenmussR., “A Quantitative Model of Ultraviolet Matrix-Assisted Laser Desorption/Ionization Including Analyte Ion Generation”, Anal. Chem.75, 2199 (2003). doi: 10.1021/ac034032r
35.
KnochenmussR., “Photoionization Pathways and Free Electrons in UV-MALDI”, Anal. Chem.76, 3179 (2004). doi: 10.1021/ac035501s
36.
KnochenmussR.StortelderA.BreukerK.ZenobiR., “Secondary ion-molecule reactions in matrix-assisted laser desorption/ionization”, J. Mass Spectrom.35, 1237 (2000). 10.1002/1096-9888(200011)35:11<1237::AID-JMS74>3.0.CO;2-O
37.
KnochenmussR.DuboisF.DaleM.J.ZenobiR., “The Matrix Suppression Effect and Ionization Mechanisms in Matrix-assisted Laser Desorption/Ionization”, Rapid Commun. Mass Spectrom.10, 871 (1996). doi: 10.1002/(SICI)1097-0231(19960610)10:8<871::AID-RCM559>3.0.CO;2-R
38.
KnochenmussR.KarbachV.WiesliU.BreukerK.ZenobiR., “The matrix suppression effect in matrix-assisted laser desorption/ionization: Application to negative ions and further characteristics”, Rapid Commun. Mass Spectrom.12, 529 (1998). doi: 10.1002/(SICI)1097-0231(19980515)12:9<529::AID-RCM188>3.0.CO;2-E
39.
KarasM.KrügerR.“Ion Formation in MALDI: The Cluster Ionization Mechanism”, Chem. Rev, 103, 427 (2003). doi: 10.1021/cr010376a
40.
WuX.SadeghiM.VertesA., “Molecular Dynamics of Matrix-Assisted Laser Desorption of Leucine Enkephalin Guest Molecules from Nicotinic Acid Host Crystal”, J. Phys. Chem. B102, 4770 (1998). doi: 10.1021/jp9806361
41.
SadeghiM.WuX.VertesA., “Conformation Changes, Complexation, and Phase Transition in Matrix-Assisted Laser Desorption”, J. Phys. Chem. B104, 2578 (2001). doi: 10.1021/jp0032715
42.
KristyanS.BencsuraA.VertesA., “Modeling the cluster formation during infrared and ultraviolet matrix-assisted laser desorption ionization of oligonucleotides in succinic acid matrix with molecular mechanics”, Theoret. Chim. Acta107, 319 (2002). doi: 10.1007/s00214-002-0342-1
43.
ZhigileiL.V.KodaliP.B.S.GarrisonB.J., “A Microscopic View of Laser Ablation”, J. Phys. Chem. B102, 2845 (1998). doi: 10.1021/jp9733781
44.
DouY.ZhigileiL.V.PostawaZ.WinogradN.GarrisonB.J., “Thickness effects of water overlayer on its explosive evaporation at heated metal surfaces”, Nucl. Instrum. Meth. Phys. Res. B180, 105 (2001). doi: 10.1016/S0168-583X(01)00403-7
45.
ZhigileiL.V.LeveugleE.GarrisonB.J.YinglingY.G.ZeifmanM.I., “Computer Simulations of Laser Ablation of Molecular Substrates”, Chem. Rev.103, 321 (2003). doi: 10.1021/cr010459r
46.
GeorgiouS.KoubenakisA., “Laser-Induced Material Ejection from Model Molecular Solids and Liquids: Mechanisms, Implications, and Applications”, Chem. Rev.103, 349 (2003) doi: 10.1021/cr010429o
47.
MeffertA.GrotemeyerJ., “Reactions in molecular clusters: Proton transfer to small amino acids”, Eur. Mass Spectrom.1, 594 (1995).
48.
FournierI.BolbachG.TabetJ.C., “Delayed extraction experiments using a repulsive potential before ion extraction: Evidence of clusters as ion precursors in UV-MALDI. Part I: Dynamical effects with the matrix 2,5-dihydroxybenzoic acid”, Int. J. Mass Spectrom.213, 203 (2002). doi: 10.1016/S1387-3806(01)00540-1
49.
HandschuhM.NettesheimS.ZenobiR., “Laser-induced molecular desorption and particle ejection from organic films”, Appl. Surf. Sci.137, 125 (1998).
50.
AlvesS.KalbererM.ZenobiR., “Direct detection of particles formed by laser ablation of matrices during matrix-assisted laser desorption/ionization”, Rapid Commun. Mass Spectrom.17, 2034 (2003). doi: 10.1002/rcm.1149
51.
KrügerR.PfenningerA.FournierI.GluckmannM.KarasM., “Analyte Incorporation and Ionization in Matrix-Assisted Laser Desorption/Ionization Visualized by pH Indicator Molecular Probes”, Anal. Chem.73, 5812 (2001). doi: 10.1021/ac010827r
52.
KrutchinskyA.N.ChaitB., “On the nature of the chemical noise in MALDI mass spectra”, J. Am. Soc. Mass Spectrom.13, 129 (2002). doi: 10.1016/S1044-0305(01)00336-1
53.
ZhangJ.FrankevichV.KnochenmussR.ZenobiR., “Program overview”, J. Am. Soc. Mass Spectrom.14, 2 (2003). doi: 10.1016/S1044-0305(03)00247-2
54.
FrankevichV.KnochenmussR.ZenobiR., “The origin of electrons in MALDI and their use for sympathetic cooling of negative ions in FTICR”, Int. J. Mass Spectrom.220, 11 (2002). doi: 10.1016/S1387-3806(02)00766-2
55.
BeavisR.C.ChaudrayT.ChaitB.T., “α-Cyano-4-hydroxycinnamic acid as a matrix for matrixassisted laser desorption mass spectromtry”, Org. Mass Spectrom.27, 156 (1992). doi: 10.1002/oms.1210270217
56.
JørgensenT.J.D.BojesenG.Rahbek-NielsonH., “The proton affinities of seven matrix-assisted laser desorption/ionization matrices correlated with the formation of multiply charged ions”, Eur. J. Mass Spectrom.4, 39 (1998).
57.
MenzelC.BerkenkampS.HillenkampF., “Infrared matrix-assisted laser desorption/ionization mass spectrometry with a transversely excited atmospheric pressure carbon dioxide laser at 10.6 μm wavelength with static and delayed ion extraction”, Rapid Commun. Mass Spectrom.13, 26 (1999). doi: 10.1002/(SICI)1097-0231(19990115)13:1<26::AID-RCM443>3.0.CO;2-N
58.
BerkenkampS.MenzelC.KarasM.HillemkampF., “Performance of Infrared Matrix-assisted Laser Desorption/Ionization Mass Spectrometry with Lasers Emitting in the 3 μm Wavelength Range”, Rapid Commun. Mass Spectrom.11, 1399 (1997). doi: 10.1002/(SICI)1097-0231(19970830)11:13<1399::AID-RCM29>3.0.CO;2-B
59.
ColletteC.De PauwE., “Calibration of the internal energy distribution of ions produced by electrospray”, Rapid Commun. Mass Spectrom.12, 165 (1998). doi: 10.1002/(SICI)1097-0231(19980227)12:4<165::AID-RCM140>3.0.CO;2-1
60.
DrahosL.HeerenR.M.A.ColletteC.De PauwE.VékeyK., “Thermal energy distribution observed in electrospray ionization”, J. Mass Spectrom.34, 1373 (1999).
61.
LuoG.MargineanI.VertesA., “Internal Energy of Ions Generated by Matrix-Assisted Laser Desorption/Ionization”, Anal. Chem.74, 6185 (2002). doi: 10.1021/ac020339z
62.
VertesA.LuoG.YeL.ChenY.MargineanI., “Laser Pulse Length Dependence of Internal Energy Transfer in UV-MALDI-MS”, Appl. Phys. A79, 823 (2004). DOI: 10.1007/s00339-004-2750-7
63.
GabelicaV.SchultzE.KarasM., “Internal energy buildup in matrix-assisted laser desorption/ionization”, J. Mass Spectrom.39, 579 (2004). doi: 10.1002/jms.651
64.
DrahosL.VékeyK., “Mass Kinetics: A theoretical model of mass spectra incorporating physical processes, reaction kinetics and mathematical descriptions”, J. Mass Spectrom.36, 237 (2001). doi: 10.1002/jms.142
65.
SpenglerB., “Post-source decay analysis in matrix-assisted laser desorption/ionization mass spectrometry of biomolecules”, J. Mass Spectrom.32, 1019 (1997). doi: 10.1002/(SICI)1096-9888(199711)32:10<1019::AID-JMS595>3.0.CO;2-G
66.
CountermanA.E.HilderbrandA.E.SrebalusC.A.ClemmerD.E., “Formation of peptide aggregates during ESI: Size, charge, composition, and contributions to noise”, J. Am. Soc. Mass Spectrom.12, 1020 (2001). doi: 10.1016/S1044-0305(01)00283-5
67.
Rodriguez-CruzS.E.KlassenJ.S.WilliamsE.R., “Hydration of gas-phase ions formed by electrospray ionization”, J. Am. Soc. Mass Spectrom.10, 958 (1999). doi: 10.1016/S1044-0305(99)00068-9
68.
LeeS.W.FreivogelP.SchindlerT.BeauchampJ.L., “Freeze-Dried Biomolecules: FT-ICR Studies of the Specific Solvation of Functional Groups and Clathrate Formation Observed by the Slow Evaporation of Water from Hydrated Peptides and Model Compounds in the Gas Phase”, J. Am. Chem. Soc.120, 11758 (1998). doi: 10.1021/ja982075x
69.
DreiswerdK.SchürenbergM.KarasM.HillenkampF., “Matrix-assisted laser desorption/ionization with nitrogen lasers of different pulse widths”, Int. J. Mass Spectrom. Ion Processes154, 171 (1996). doi: 10.1016/0168-1176(96)04377-7
70.
WangB.H.DreiswerdK.BahrU.KarasM., “Gas-phase cationization and protonation of neutrals generated by matrix-assisted laser desorption”, J. Am. Soc. Mass Spectrom.4, 393 (1993). doi: 10.1016/1044-0305(93)85004-H
71.
WesmacottG.EnsW.HillenkampF.DreiswerdK.SchürnebergM., “The influence of laser fluence on ion yield in matrix-assisted laser desorption ionization mass spectrometry”, Int. J. Mass Spectrom.221, 67 (2002). doi: 10.1016/S1387-3806(02)00898-9
72.
NelsonR.W.McLeanM.A.HutchensT.W., “Quantitative Determination of Proteins by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry”, Anal. Chem.66, 1408 (1994). doi: 10.1021/ac00081a008
73.
WangB.H.DreiswerdK.BahrU.KarasM.HillenkampF., “Gas-phase cationization and protonation of neutrals generated by matrix-assisted laser desorption”, J. Am. Soc. Mass Spectrom.4, 393 (1993). doi: 10.1016/1044-0305(93)85004-H
74.
KinselG.R.EdmondsonR.D.RussellD.H., “Profile and Flight Time Analysis of Bovine Insulin Clusters as a Probe of Matrix-assisted Laser Desorption/Ionization Ion Formation Dynamics”, J. Mass Spectrom.32, 714 (1997). doi: 10.1002/(SICI)1096-9888(199707)32:7<714::AID-JMS523>3.0.CO;2-1
75.
LivadarisV.BlaisJ.C.TabetJ.C., “Formation of nonspecific protein cluster ions in matrix-assisted laser desorption/ionization: Abundances and dynamical aspects”, Eur. J. Mass Spectrom.6, 409 (2000).
76.
FrankevichV.ZhangJ.DashtevM.ZenobiR., “Production and fragmentation of multiply charged ions in “electron-free” matrix-assisted laser desorption/ionization”, Rapid Commun. Mass Spectrom.17, 2343 (2003). doi: 10.1002/rcm.1194
77.
SteenvoordenR.J.J.M.BreukerK.ZenobiR., “The gas-phase basicities of matrix-assisted laser desorption/ionization matrices”, Eur. Mass Spectrom.3, 339 (1997).
78.
BurtonR.D.WatsonC.H.EylerJ.R.LangG.L.PowellD.H.AveryM.Y., “Proton Affinities of Eight Matrices Used for Matrix-assisted Laser Desorption/Ionization”, Rapid Commun. Mass Spectrom.11, 443 (1997). doi: 10.1002/(SICI)1097-0231(199703)11:5<443::AID-RCM897>3.0.CO;2-3
79.
NelsonC.M.CrellinK.BerryJ.BeauchampJ.L.SmithL.M., Proc. of the 44th ASMS Conference.Portland, Oregon, USA, p. 733 (1996).
80.
MarzaS.P.RajuN.P.VairamaniM., “Estimation of the proton affinity values of fifteen matrix-assisted laser desorption/ionization matrices under electrospray ionization conditions using the kinetic method”, J. Am. Soc. Mass Spectrom.15, 431 (2004). doi: 10.1016/j.jasms.2003.12.001
81.
YassinF.H.MarynickD.S., “Thermodynamic properties of MALDI matrices”. Abstracts of Papers, 227th ACS National Meeting, Anaheim, CA, United States, March 28—April 1, 2004 (2004), COMP—211. CODEN: 69FGKM AN 2004:224360 CAPLUS
82.
McLuckeyS.A.CameronD.CooksR.G., “Proton affinities from dissociations of proton-bound dimers”, J. Am. Chem. Soc.103, 1313 (1981). doi: 10.1021/ja00396a001
83.
GronertS., “An ab Initio Study of Proton Transfers from Gas-Phase Dications: Complications in Kinetic Methods for Determining Acidities”, J. Am. Chem. Soc.118, 3525 (1996). doi: 10.1021/ja952728z
84.
LiasS.G.HunterE.P.L., J. Phys. Chem. Ref. Data27, 413 (1998).
85.
SummerL.W.HuangY.RussellD.H., Proc. of the 44th ASMS Conference.Portland, Oregon, USA, pp. 271–272 (1996).
86.
VékeyK., “Internal Energy Effects in Mass Spectrometry”, J. Mass Spectrom.31, 445 (1996). doi: 10.1002/(SICI)1096-9888(199605)31:5<445::AID-JMS354>3.0.CO;2-G
87.
PfeiferT.DrewelloM.SchierhornA., “Using a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer for combined in-source decay/post-source decay experiments”, J. Mass Spectrom.34, 644 (1999). doi: 10.1002/(SICI)1096-9888(199906)34:6<644::AID-JMS816>3.0.CO;2-H
88.
LavineG.AllisonJ., “Evaluation of bumetanide as a matrix for prompt fragmentation matrix-assisted laser desorption/ionization and demonstration of prompt fragmentation/post-source decay matrix-assisted laser desorption/ionization mass spectrometry”, J. Mass Spectrom.34, 741 (1999). doi: 10.1002/(SICI)1096-9888(199907)34:7<741::AID-JMS827>3.0.CO;2-F
89.
SzilagyiZ.VarneyJ.E.DerrickP.J.VékeyK., “Dependence of matrix-assisted laser desorption/ionization post-source decay spectra on laser power”, Rapid Commun. Mass Spectrom.12, 489 (1998). doi: 10.1002/(SICI)1097-0231(19980430)12:8<489::AID-RCM187>3.0.CO;2-H
90.
KöcherT.EngströmA.ZubarevA., “Fragmentation of Peptides in MALDI In-Source Decay Mediated by Hydrogen Radicals”, Anal. Chem.77, 172 (2005). doi: 10.1021/ac0489115
91.
BaerT.MayerP.M., “Statistical Rice-Ramsperger-Kassel-Marcus quasiequilibrium theory calculations in mass spectrometry”, J. Am. Soc. Mass Spectrom.8, 103 (1997). doi: 10.1016/S1044-0305(96)00212-7
92.
LinQ.KnochenmussR., “Ionization energy reductions in small 2,5-dihydroxybenzoic acid-proline clusters”, Rapid Commun. Mass Spectrom.15, 1422 (2001). doi: 10.1002/jms.374
93.
KinselG.R.KnochenmussR.SetzP.LandG.M.GohS.K.ArchibongE.F.HardestyJ.H.MarynickD.S., “Ionization energy reductions in small 2,5-dihydroxybenzoic acid-proline clusters”, J. Mass Spectrom.108, 1131 (2002). doi: 10.1002/jms.374
94.
KinselG.R.ZhaoQ.NarayanasamyJ.YassinF.DiasH.V. RasikaNiesnerB.PraterK.St MarieC.LyL.MarvnickD.S., “Arginine/2,5-Dihydroxybenzoic Acid Clusters: An Experimental and Computational Study of the Gas-Phase and Solid-State Systems”, J. Phys. Chem. A108, 3153 (2004). doi: 10.1021/jp031207s
95.
FrankevichV.ZhangJ.FriessS.D.DashtievM.ZenobiR., “Role of Electrons in Laser Desorption/Ionization Mass Spectrometry”, Anal. Chem.75, 6063 (2003). doi: 10.1021/ac034436j
96.
WilliamsE.R., “Perspective Proton Transfer Reactivity of Large Multiply Charged Ions”, J. Mass Spectrom.31, 831 (1996). doi: 10.1002/(SICI)1096-9888(199608)31:8<831::AID-JMS392>3.0.CO;2-7
97.
BaranovV.BohmeD.K., “Gas-phase reactions of singly and multiply-charged fullerene cations, C60x+ (x = 1–3), with iron pentacarbonyl: Kinetic control by Coulombic barriers”, Int. J. Mass Spectrom.165/166, 249 (1997). doi: 10.1016/S0168-1176(97)00160-2
98.
IavaroneA.T.JurchenJ.C.WilliamsE.R., “Effects of solvent on the maximum charge state and charge state distribution of protein ions produced by electrospray ionization”, J. Am. Soc. Mass Spectrom.11, 976 (2000). doi: 10.1016/S1044-0305(00)00169-0
Meot-Ner (Mautner)M.SieckL.W.ScheinerS.DuanX., “The Ionic Hydrogen Bond. 5. Polydentate and Solvent-Bridged Structures. Complexing of the Proton and the Hydronium Ion by Polyethers”, J. Am. Chem. Soc.116, 7846 (1994). doi: 10.1021/ja00096a047
101.
ChrismanP.A.NewtonK.A.ReidG.E.WellsJ.M.McLuckeyS.A., “Loss of charged versus neutral heme from gaseous holomyoglobin ions”, Rapid Commun. Mass Spectrom.15, 2334 (2001). doi: 10.1002/rcm.512
BraumanJ.I.J., “Some historical background on the doublewell potential model”, J. Mass Spectrom.30, 1649 (1995). doi: 10.1002/jms.1190301203
104.
GongS.CamaraE.HeF.GreenM.K.LebrillaC.B., “Chiral recognition and the deprotonation reaction of gas-phase cytochrome c ions”, Int. J. Mass Spectrom.185–187, 401 (1999). doi: Doi:10.1016/S1387-3806(98)14148-9
105.
SchnierP.D.GrossD.S.WilliamsE.R., “Electrostatic Forces and Dielectric Polarizability of Multiply Protonated Gas-Phase Cytochrome c Ions Probed by Ion/Molecule Chemistry”, J. Am. Chem. Soc, 117, 6747 (1995). doi: 10.1021/ja00130a015
106.
GrossD.S.ZhaoY.WilliamsE.R., “Dissociation of heme-globin complexes by blackbody infrared radiative dissociation: Molecular specificity in the gas phase?”, J. Am. Soc. Mass Spectrom.8(5), 519 (1997). doi: 10.1016/S1044-0305(97)00010-X
107.
GronertS., “Determining the gas-phase properties and reactivities of multiply charged ions”, J. Mass Spectrom.34, 787 (1999). doi: 10.1002/(SICI)1096-9888(199908)34:8<787::AID-JMS847>3.0.CO;2-O
108.
KaltashovI.A.FenselauC., “A Direct Comparison of “First” and “Second” Gas Phase Basicities of the Octapeptide RPPGFSPF”, J. Am. Chem. Soc.117, 9906 (1995). doi: 10.1021/ja00144a017
109.
KaltashovI.A.FenselauC., “Proton locations in doubly charged peptides and association with specific fragmentation pathways”, Int. J. Mass Spectrom. Ion Processes160, 331(1997). doi: 10.1016/S0168-1176(96)04491-6
110.
WongP.S.H.MaS.CooksR.G., “Ionization Energy Determination by the Kinetic Method”, Anal. Chem.68, 4254 (1996). doi: 10.1021/ac960566z
111.
DrahosL.VékeyK., J. Chem. Phys.“How closely related are the effective and the real temperature”, 34, 79 (1999).
112.
ErvinK.M.“Microcanonical analysis of the kinetic method. The meaning of the “effective temperature”, Int. J. Mass Spectrom.195/196, 271 (2000). doi: 10.1016/S1387-3806(99)00176-1
113.
BreukerK.KnochenmussR.ZenobiR., “Matrix-assisted laser desorption/chemical ionization with reagent ion generation directly from a liquid matrix”, Int. J. Mass Spectrom.176, 149 (1998). doi: 10.1016/S1387-3806(98)14015-0
114.
DreisewerdK.ShürenbergM.KarasM.HillenkampF., “Influence of the laser intensity and spot size on the desorption of molecules and ions in matrix-assisted laser desorption/ionization with a uniform beam profile”, Int. J. Mass Spectrom. Ion Processes141, 127 (1995). doi: 10.1016/0168-1176(94)04108-J
115.
HandschuhM.NettesheimS.ZenobiR., “Is laser heating advantageous for thermal desorption of large polar molecules?”, J. Chem. Phys.107(7), 2603 (1997). doi: 10.1063/1.474617
116.
DreisewerdK.SchürnebergM.KarasM.HillenkampF., “Matrix-assisted laser desorption/ionization with nitrogen lasers of different pulse widths”, Int. J. Mass Spectrom. Ion Processes154, 171 (1996). doi: 10.1016/0168-1176(96)04377-7
