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Couto N, Barber J, Gaskell SJ. Matrix-assisted laser desorption/ionisation mass spectrometric response factors of peptides generated using different proteolytic enzymes. JOURNAL OF MASS SPECTROMETRY : JMS 2011; 46:1233-1240. [PMID: 22223413 DOI: 10.1002/jms.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Matrix-assisted laser desorption/ionisation (MALDI) mechanisms and the factors that influence the intensity of the ion signal in the mass spectrum remain imperfectly understood. In proteomics, it is often necessary to maximise the peptide response in the mass spectrum, especially for low abundant proteins or for proteolytic peptides of particular significance. We set out to determine which of the common proteolytic enzymes give rise to peptides with the best response factors under MALDI conditions. Standard proteins were enzymatically digested using four common proteases. We assessed relative response factors by coanalyzing the resulting digests. Thus, when tryptic peptides were added in equimolar quantities to their corresponding Asp-N, chymotrypsin and Glu-C digests, tryptic peptide signals were always predominant in the resulting MALDI mass spectra. Observable peaks attributable to non-tryptic peptides generally contained a terminal basic residue. It was proposed that a terminal basic residue has a disproportionate influence upon gas-phase basicity, and this hypothesis was supported by experiments with model isotopically labelled peptides. Experiments applying Cook's kinetic method showed that the peptide with a C-terminal arginine residue was more basic than the equivalent peptide with an N-terminal arginine, which was more basic than the peptide in which the arginine was mid-chain. Thus, the observation of the higher MALDI mass spectrometry response factors of tryptic peptides in comparison with peptides derived using other proteolytic enzymes corresponds with higher gas-phase basicities and may, along with other factors such as the complexity of the digest, influence the choice of enzyme in "bottom-up" proteomic experiments.
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Affiliation(s)
- Narciso Couto
- Michael Barber Centre for Mass Spectrometry, Manchester Interdisciplinary Biocentre, Princess Road, University of Manchester, Manchester, M1 7DN, UK
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2
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Wang J, Aubry A, Bolgar MS, Gu H, Olah TV, Arnold M, Jemal M. Effect of mobile phase pH, aqueous-organic ratio, and buffer concentration on electrospray ionization tandem mass spectrometric fragmentation patterns: implications in liquid chromatography/tandem mass spectrometric bioanalysis. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2010; 24:3221-3229. [PMID: 20972995 DOI: 10.1002/rcm.4748] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Liquid chromatography/tandem mass spectrometry (LC/MS/MS) based on selected reaction monitoring (SRM) is the standard methodology in quantitative analysis of administered xenobiotics in biological samples. Utilizing two SRM channels during positive electrospray ionization (ESI) LC/MS/MS method development for a drug compound containing two basic functional groups, we found that the response ratio (SRM1/SRM2) obtained using an acidic mobile phase was dramatically different from that obtained using a basic mobile phase. This observation is different from the well-established phenomenon of mobile phase affecting the [M+H](+) response, which is directly related to the amount of the [M+H](+) ions produced during the ionization. Results from follow-up work reported herein revealed that the MS/MS fragmentation patterns of four drug or drug-like compounds are affected not only by the pH, but also by the aqueous-organic ratio of the mobile phase and the buffer concentration at a given apparent pH. The observed phenomenon can be explained by invoking that a mixture of [M+H](+) ions of the same m/z value for the analyte is produced that is composed of two or more species which differ only in the site of the proton attachment, which in turn affects their MS/MS fragmentation pattern. The ratio of the different protonated species changes depending on the pH, aqueous-organic ratio, or ionic strength of the mobile phase used. The awareness of the mobile phase dependency of the MS/MS fragmentation pattern of precursor ions of identical m/z value will influence LC/MS/MS-based bioanalytical method development strategies. Specifically, we are recommending that multiple SRM transitions be monitored during mobile phase screening, with the MS/MS parameters used for each SRM optimized for the composition of the mobile phase (pH, organic percentage, and ionic strength) in which the analyte elutes.
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Affiliation(s)
- Jian Wang
- Bristol-Myers Squibb, Research & Development, Analytical Research and Development, Princeton, NJ 08543, USA.
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3
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Shek PYI, Zhao J, Ke Y, Siu KWM, Hopkinson AC. Fragmentations of protonated arginine, lysine and their methylated derivatives: concomitant losses of carbon monoxide or carbon dioxide and an amine. J Phys Chem A 2007; 110:8282-96. [PMID: 16821812 DOI: 10.1021/jp055426k] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The fragmentation pathways of protonated arginine, protonated N(alpha),N(alpha)-dimethylarginine, the N(alpha),N(alpha),N(alpha)-trimethylarginine ion, three protonated N(epsilon),N(epsilon)-dimethyllysines, and three permanent lysine ions in which the charge is fixed by trimethylation are reported. Ion assignment was facilitated by (15)N-labeling and deuterium substitution. The chemistries are dominated by charge-induced elimination of the amino groups as neutrals, including dimethylamine, trimethylamine and guanidine. Competitive losses of the alpha-amino and side-chain amino groups were observed; these losses led to intermediates that had different structures and different subsequent dissociation reactions. Concomitant losses of CO or CO(2) with these amines were also commonly observed. However, the ionic products of amine losses did not subsequently lose CO or CO(2), suggesting strongly that in these concomitant eliminations, it is the CO or CO(2) that was first eliminated, followed immediately by the loss of the amine. Results of density functional theory calculations on protonated arginine and protonated N(alpha),N(alpha)-dimethylarginine reveal that, in such concomitant eliminations, the dissociating complex is vibrationally hot and the intermediate ion formed by losing CO or CO(2) can immediately dissociate to eliminate the amine.
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Affiliation(s)
- P Y Iris Shek
- Department of Chemistry and Centre for Research in Mass Spectrometry, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3
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4
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Leitner A, Foettinger A, Lindner W. Improving fragmentation of poorly fragmenting peptides and phosphopeptides during collision-induced dissociation by malondialdehyde modification of arginine residues. JOURNAL OF MASS SPECTROMETRY : JMS 2007; 42:950-9. [PMID: 17539043 DOI: 10.1002/jms.1233] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Despite significant technological and methodological advancements in peptide sequencing by mass spectrometry, analyzing peptides that exhibit only poor fragmentation upon collision-induced dissociation (CID) remains a challenge. A major cause for unfavorable fragmentation is insufficient proton 'mobility' due to charge localization at strongly basic sites, in particular, the guanidine group of arginine. We have recently demonstrated that the conversion of the guanidine group of the arginine side chain by malondialdehyde (MDA) is a convenient tool to reduce the basicity of arginine residues and can have beneficial effects for peptide fragmentation. In the present work, we have focused on peptides that typically yield incomplete sequence information in CID-MS/MS experiments. Energy-resolved tandem MS experiments were carried out on angiotensins and arginine-containing phosphopeptides to study in detail the influence of the modification step on the fragmentation process. MDA modification dramatically improved the fragmentation behavior of peptides that exhibited only one or two dominant cleavages in their unmodified form. Neutral loss of phosphoric acid from phosphopeptides carrying phosphoserine and threonine residues was significantly reduced in favor of a higher abundance of fragment ions. Complementary experiments were carried out on three different instrumental platforms (triple-quadrupole, 3D ion trap, quadrupole-linear ion trap hybrid) to ascertain that the observation is a general effect.
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Affiliation(s)
- Alexander Leitner
- Department of Analytical Chemistry and Food Chemistry, University of Vienna, Waehringer Strasse 38, 1090 Vienna, Austria.
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Andriole EJ, Colyer KE, Cornell E, Poutsma JC. Proton Affinity of Canavanine and Canaline, Oxyanalogues of Arginine and Ornithine, from the Extended Kinetic Method. J Phys Chem A 2006; 110:11501-8. [PMID: 17020263 DOI: 10.1021/jp063081f] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The absolute proton affinities of the nonprotein amino acids canavanine and canaline have been determined using the extended kinetic method in an electrospray ionization quadrupole ion trap instrument. Canavanine results from the substitution of an oxygen atom for the delta-CH2 group in the side chain of the protein amino acid arginine, whereas canaline results from a similar substitution at the delta-CH2 group in the side chain of ornithine. Absolute proton affinities of 1001+/-9 and 950+/-7 kJ/mol are obtained for canavanine and canaline, respectively. For canaline, this proton affinity is in excellent agreement with theoretical predictions obtained using the hybrid density functional theory method B3LYP/6-311++G**//B3LYP/6-31+G*. For canavanine, theory predicts a somewhat larger proton affinity of 1015 kJ/mol. Oxygen atom substitution in these nonprotein amino acids results in a decrease in their proton affinities of 40-50 kJ/mol compared to arginine and ornithine.
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Affiliation(s)
- Erica J Andriole
- Department of Chemistry, The College of William and Mary, Williamsburg, Virginia 23187-8795, USA
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6
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Foettinger A, Leitner A, Lindner W. Derivatisation of arginine residues with malondialdehyde for the analysis of peptides and protein digests by LC-ESI-MS/MS. JOURNAL OF MASS SPECTROMETRY : JMS 2006; 41:623-32. [PMID: 16541401 DOI: 10.1002/jms.1020] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
In this study a selective tagging strategy for the derivatisation of arginine residues in peptides is presented. It is based on the reaction of the guanidine group of the arginine side-chain with malondialdehyde (MDA) under strongly acidic conditions, in which a stable pyrimidine ring is formed. The reaction conditions have been optimised so that quantitative modification can be achieved for a variety of peptides. The label has a strong influence on the polarity and basicity of the arginine side-chain and thus on the chromatographic and mass spectrometric properties of arginine-containing peptides. For example, retention, particularly of small and polar peptides as well as arginine-rich peptides, is significantly increased by derivatisation, and therefore sensitivity is also enhanced in liquid chromatography-mass spectrometry (LC-MS). The arginine side-chain also has a strong impact on the fragmentation behaviour of peptides in tandem mass spectrometry. This has been investigated for standard peptides for which, in some cases, significantly more fragment ions were formed after derivatisation. Finally, the method was tested for tryptic digests of standard proteins to demonstrate how the tagging strategy can give improved or complementary information for protein identification.
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Affiliation(s)
- Alexandra Foettinger
- Institute of Analytical Chemistry and Food Chemistry, University of Vienna, 1090 Vienna, Austria
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7
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Grewal RN, El Aribi H, Harrison AG, Siu KWM, Hopkinson AC. Fragmentation of Protonated Tripeptides: The Proline Effect Revisited. J Phys Chem B 2004. [DOI: 10.1021/jp031093k] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- R. Natasha Grewal
- Department of Chemistry and Centre for Research in Mass Spectrometry, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3, and Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5S 3H6
| | - Houssain El Aribi
- Department of Chemistry and Centre for Research in Mass Spectrometry, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3, and Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5S 3H6
| | - Alex G. Harrison
- Department of Chemistry and Centre for Research in Mass Spectrometry, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3, and Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5S 3H6
| | - K. W. Michael Siu
- Department of Chemistry and Centre for Research in Mass Spectrometry, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3, and Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5S 3H6
| | - Alan C. Hopkinson
- Department of Chemistry and Centre for Research in Mass Spectrometry, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3, and Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario, Canada M5S 3H6
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8
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Barr JM, Van Stipdonk MJ. Multi-stage tandem mass spectrometry of metal cationized leucine enkephalin and leucine enkephalin amide. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2002; 16:566-578. [PMID: 11870894 DOI: 10.1002/rcm.612] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We have examined the multi-stage collision induced dissociation (CID) of metal cationized leucine enkephalin, leucine enkephalin amide, and the N-acetylated versions of the peptides using ion trap mass spectrometry. In accord with earlier studies, the most prominent species observed during the multi-stage CID of alkali metal cationized leucine enkephalin are the [b(n) + 17 + Cat]+ ions. At higher CID stages (i.e. >MS(4)), however, dissociation of the [b2 + 17 + Cat]+ ion, a cationized dipeptide, results in the production of [a(n) -1 + Cat]+ species. The multi-stage CID of Ag+ cationized leucine enkephalin can be initiated with either the [b(n) -1 + Ag]+ or [b(n) + 17 + Ag]+ ions produced at the MS/MS stage. For the former, sequential CID stages cause, in general, the loss of CO, and then the loss of the imine of the C-terminal amino acid, to reveal the amino acid sequence. Similar to the alkali cationized species, CID of [b2 -1 + Ag]+ produces prominent [a(n) -1 + Ag]+ ions. The multi-stage CID of argentinated peptides is reminiscent of fragmentation observed for protonated peptides, in that a series of (b(n)) and (a(n)) type ions are generated in sequential CID stages. The Ag+ cation is similar to the alkali metals, however, in that the [b(n) + 17 + Ag]+ product is produced at the MS/MS and MS3 stages, and that sequential CID stages cause the elimination of amino acid residues primarily from the C-terminus. We found that N-acetylation of the peptide significantly influenced the fragmentation pathways observed, in particular by promoting the formation of more easily interpreted (in the context of unambiguous sequence determination) dissociation spectra from the [b2 + 17 + Li]+, [b2 + 17 + Na]+ and [b2 -1 + Ag]+ precursor ions. Our results suggest, therefore, that N-acetylation may improve the efficacy of multi-stage CID experiments for C-terminal peptide sequencing in the gas phase. For leucine enkephalin amide, only the multi-stage CID of the argentinated peptide allowed the complete amino acid sequence to be determined from the C-terminal side.
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Affiliation(s)
- J M Barr
- Department of Chemistry, Wichita State University, Wichita, KS 67260-0051, USA
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Mohammed S, Chalmers MJ, Gielbert J, Ferro M, Gora L, Smith DC, Gaskell SJ. A novel tandem quadrupole mass spectrometer allowing gaseous collisional activation and surface induced dissociation. JOURNAL OF MASS SPECTROMETRY : JMS 2001; 36:1260-1268. [PMID: 11754117 DOI: 10.1002/jms.217] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A novel tandem quadrupole mass spectrometer is described that enables gaseous collision-induced dissociation (CID) and surface-induced dissociation (SID) experiments. The instrument consists of a commercially available triple quadrupole mass spectrometer connected to an SID region and an additional, orthogonal quadrupole mass analyser. The performance of the instrument was evaluated using leucine-enkephalin, allowing a comparison between CID and SID, and with previous reports of other SID instruments. The reproducibility of SID data was assessed by replicate determinations of the collision energy required for 50% dissociation of leucine-enkephalin; excellent precision was observed (standard deviation of 0.6 eV) though, unexpectedly, the reproducibility of the equivalent figure for CID was superior. Several peptides were analysed using SID in conjunction with liquid secondary-ion mass spectrometry or electrospray; a comparison of the fragmentation of singly protonated peptide ions and the further dissociation of y-type fragments was consistent with the equivalence of the latter fragments to protonated peptides. Few product ions attributable to high-energy cleavages of amino acid side-chains were observed. The SID properties were investigated of a series of peptides differing only in the derivatization of a cysteine residue; similar decomposition efficiencies were observed for all except the cysteic acid analogue, which demonstrated significantly more facile fragmentation.
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Affiliation(s)
- S Mohammed
- Michael Barber Centre for Mass Spectrometry, Department of Chemistry, UMIST, Sackville Street, PO Box 88, Manchester M60 1QD, UK
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10
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Chu IK, Shoeib T, Guo X, Rodriquez CF, Lau TC, Hopkinson AC, Siu KW. Characterization of the product ions from the collision-induced dissociation of argentinated peptides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2001; 12:163-175. [PMID: 11212001 DOI: 10.1016/s1044-0305(00)00216-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Tandem mass spectrometry performed on a pool of 18 oligopeptides shows that the product ion spectra of argentinated peptides, the [bn + OH + Ag]+ ions and the [yn - H + Ag]+ ions bearing identical sequences are virtually identical. These observations suggest strongly that these ions have identical structures in the gas phase. The structures of argentinated glycine, glycylglycine, and glycylglycylglycine were calculated using density functional theory (DFT) at the B3LYP/DZVP level of theory; they were independently confirmed using HF/LANL2DZ. For argentinated glycylglycylglycine, the most stable structure is one in which Ag+ is tetracoordinate and attached to the amino nitrogen and the three carbonyl oxygen atoms. Mechanisms are proposed for the fragmentation of this structure to the [b2 + OH + Ag]+ and the [Y2 - H + Ag]+ ions that are consistent with all experimental observations and known calculated structures and energetics. The structures of the [b2 - H + Ag]+ and the [a2 - H + Ag]+ ions of glycylglycylglycine were also calculated using DFT. These results confirm earlier suggestions that the [b2 - H + Ag]+ ion is an argentinated oxazolone and the [a2 - H + Ag]+ an argentinated immonium ion.
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Affiliation(s)
- I K Chu
- Department of Chemistry and Centre for Research in Mass Spectrometry, York University, Toronto, Ontario, Canada
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11
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Bauer MD, Sun Y, Keough T, Lacey MP. Sequencing of sulfonic acid derivatized peptides by electrospray mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2000; 14:924-929. [PMID: 10825258 DOI: 10.1002/(sici)1097-0231(20000530)14:10<924::aid-rcm967>3.0.co;2-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
We report the application of nanoelectrospray ionization tandem mass spectrometry (nES-MS/MS) and capillary LC/microelectrospray MS/MS (cLC/&mgr;ES-MS/MS) for sequencing sulfonic acid derivatized tryptic peptides. These derivatives were specifically prepared to facilitate low-energy charge-site-initiated fragmentation of C-terminal arginine-containing peptides, and to enhance the selective detection of a single series of y-type fragment ions. Both singly and doubly protonated peptides were analyzed by MS/MS and the results were compared with those from their derivatized counterparts. Model peptides and peptides from tryptic digests of gel-isolated proteins were analyzed. Derivatized singly protonated peptides fragment in the same way by nES-MS/MS as they do by post-source decay matrix-assisted laser desorption/ionization mass spectrometry (PSD-MALDI-MS). They produce fragment ion spectra dominated by y-ions, and the simplified spectra are readily interpreted de novo. Doubly protonated peptides fragment in much the same way as their non-derivatized doubly protonated counterparts. The fragmentation of doubly protonated derivatives is especially useful for sequencing peptides that possess a proline residue near the N-terminus of the molecule. The singly protonated forms of these proline-containing derivatives often show enhanced fragmentation on the N-terminal side of the proline and considerably reduced fragmentation on the C-terminal side. In addition, sulfonic acid derivatization increases the in-source fragmentation of arginine-containing peptides. This could be useful for sequence verification and sequence tagging for use in single stage mass spectrometry. Copyright 2000 John Wiley & Sons, Ltd.
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Affiliation(s)
- MD Bauer
- The Procter and Gamble Company, Miami Valley Laboratories, P.O. Box 538707, Cincinnati, OH 45253-8707, USA
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12
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Adamczyk M, Gebler JC, Wu J. Charge derivatization of peptides to simplify their sequencing with an ion trap mass spectrometer. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 1999; 13:1413-1422. [PMID: 10407332 DOI: 10.1002/(sici)1097-0231(19990730)13:14<1413::aid-rcm657>3.0.co;2-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The low energy collision-induced dissociation of fixed-charge derivatives [tris(2,4,6-trimethoxyphenyl)phosphonium] of peptides was investigated using an electrospray ion trap mass spectrometer. The fixed charge directed the fragmentation pattern and generated solely N-terminal fragments with minimal internal rearrangement, regardless of the presence and position of basic amino acids in the peptide chain. Generally only b-type ions, accompanied by less intense a-type ions, were observed, depending on the collision energy. It was observed that the fixed charge controlled the fragmentation beyond typical MS/MS, and thus the capacity of the ion trap to perform multiple stage fragmentation (MS(n)) was found particularly useful for obtaining the complete sequence information of the peptides.
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Affiliation(s)
- M Adamczyk
- Department of Chemistry (9NM), Abbott Diagnostic Division, Abbott Laboratories, Abbott Park, IL 60064-6016, USA.
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13
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Kratzer R, Eckerskorn C, Karas M, Lottspeich F. Suppression effects in enzymatic peptide ladder sequencing using ultraviolet - matrix assisted laser desorption/ionization - mass spectormetry. Electrophoresis 1998; 19:1910-9. [PMID: 9740051 DOI: 10.1002/elps.1150191109] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The techniques of enzymatic and chemical peptide ladder sequencing, coupled with ultraviolet - matrix assisted laser desorption/ionization - mass spectrometry (UV-MALDI-MS) have been improving continuously in the last five years and have now become important tools for primary structure identification. In this work, signal suppression effects, appearing in UV-MALDI-MS (excitation 337 nm) of ladder peptides, were investigated using the 17-amino acid peptide dynorphin A. We show, with examples of simple "two-peptide" systems and more complex "multi-peptide" systems, that suppression effects do in fact exist. The magnitude of the observed suppression is strongly dependent upon both the nature and the amount of the suppressing peptide. Suppression behavior of individual ladder peptides was investigated on equimolar mixtures of ten ladder peptides. Significant signal suppression was recorded for all ladder peptides, with some of them being approximately 170 times lower in signal intensity than the pure, i.e., unsuppressed peptide at the same concentration. For the investigated system--dynorphin A, 4-hydroxy-alpha-cyanocinnamic acid (4-HCCA) matrix, UV excitation--a correlation between the extent of suppression and an intractable combination of peptide hydrophobicity and the presence of several basic amino acids can be seen.
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Affiliation(s)
- R Kratzer
- Max-Planck-Institute for Biochemistry, Analytical Protein Chemistry Group, Martinsried, Germany.
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14
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Gur EH, de Koning LJ, Nibbering NM. The bimolecular hydrogen-deuterium exchange behavior of protonated alkyl dipeptides in the gas phase. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 1995; 6:466-477. [PMID: 24214299 DOI: 10.1016/1044-0305(95)00189-k] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/1994] [Revised: 12/23/1994] [Accepted: 01/04/1995] [Indexed: 06/02/2023]
Abstract
As part of an ongoing characterization of the intrinsic chemical properties of peptides, thermal hydrogen-deuterium exchange has been studied for a series of fast-atom-bombardment-generated protonated alkyldipeptides and related model compounds in the reaction with D2O, CH3OD, and ND3 in a Fourier transform ion cyclotron resonance mass spectrometer. Despite the very large basicity difference between the dipeptides and the D2O and CH3OD exchange reagents, efficient exchange of all active hydrogen atoms occurs. From the kinetic data it appears that exchange of the amino, amide, and hydroxyl hydrogens proceeds with different efficiencies, which implies that the proton in thermal protonated dipeptides is immobile. The selectivity of the exchange at the different basic sites is governed by the nature of both the dipeptide and the exchange reagent. The results indicate that reversible proton transfer in the reaction complexes, which effectuates the deuterium incorporation, is assisted by formation of multiple hydrogen bonds between the reagents. Exchange is considered to proceed via the intermediacy of different competing intermediate complexes, each of which specifically leads to deuterium incorporation at different basic sites. The relative stabilization of the competing intermediate complexes can be related to the relative efficiencies of deuterium incorporation at different basic sites in the dipeptide. For all protonated dipeptides studied, the exchange in the reaction with ND3 proceeds with unit efficiency, whereas all active hydrogen atoms are exchanged equally efficiently. Evidently specific multiple hydrogen bond formations are far less important in the reversible proton transfers with the relatively basic ammonia, which allows effective randomization of all active hydrogen atoms in the reaction complexes.
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Affiliation(s)
- E H Gur
- Institute of Mass Spectrometry, University of Amsterdam, Nieuwe Achtergracht 129, 1018 WS, Amsterdam, The Netherlands
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15
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Kiplinger JP, Guadliana MA. Structural analysis of rapamycin and related compounds using [M + Li]+ ions generated by liquid secondary ion mass spectrometry. ACTA ACUST UNITED AC 1994. [DOI: 10.1002/oms.1210290809] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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