Oxidation Artifacts in the Electrospray Mass Spectrometry of Aβ Peptide

Chen, Maolian; Cook, Kelsey D.

doi:10.1021/ac061743r

Cited by 108 publications

(129 citation statements)

References 32 publications

(75 reference statements)

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“…Numerous studies have shown the effects of electrochemical reactions associated with the ESI spray process for a wide variety of chemical compounds. [8][9][10][11] To our knowledge, such reactions have not yet been reported for PAMAM dendrimers.In this study, we report the formation of unexpected ions during ESI-MS analyses of PAMAM generation 1 (G1) (Fig. 1) in negative ion mode.…”

mentioning

confidence: 88%

Formation of unexpected ions from a first‐generation polyamidoamine dendrimer by use of methanol: an artefact due to electrospray emitter corrosion?

Maire

Lange

2010

Rapid Comm Mass Spectrometry

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We report the formation of unexpected ions during the analyses of a first-generation polyamidoamine dendrimer in negative ion mode using an ion trap equipped with an electrospray ionisation source. These surprising ions corresponded to an increase of 12 m/z units over those expected. The formation of the unexpected ions was dependent on the tuning of the solution flow rate and the capillary high voltage. In addition, measurements of unusual value of the current suggested that a reaction was occurring in the corona plasma. The influence of methanol in this phenomenon was demonstrated by using CD(3)OH in the sample preparation. We propose two structures to explain the observed adduct based on the results of MS(2) experiments and by referring to previous work dealing with 12 m/z units addition. We showed that a corona discharge caused by alterations taking place to the electrospray capillary emitter was the origin of these unexpected ions. Finally, we discuss the mechanism involved in the formation of the ions and we propose means to control such artefacts.

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mentioning

confidence: 88%

Formation of unexpected ions from a first‐generation polyamidoamine dendrimer by use of methanol: an artefact due to electrospray emitter corrosion?

Maire

Lange

2010

Rapid Comm Mass Spectrometry

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“…In some cases, two distinct chromatographic peaks for the same modified peptide were observed, suggesting the presence of some adduct in the original digest. This was especially common for methionine-oxidized peptides (49). One less discussed modification was transpeptidation, which involves the transfer of a basic residue to the N or C terminus of a peptide.…”

Section: Overview Of Library Buildingmentioning

confidence: 99%

Tandem Mass Spectral Libraries of Peptides in Digests of Individual Proteins: Human Serum Albumin (HSA)

Dong

Yan

Kilpatrick

et al. 2014

Molecular & Cellular Proteomics

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This work presents a method for creating a mass spectral library containing tandem spectra of identifiable peptide ions in the tryptic digestion of a single protein. Human serum albumin (HSA 1 ) was selected for this purpose owing to its ubiquity, high level of characterization and availability of digest data. The underlying experimental data consisted of ϳ3000 one-dimensional LC-ESI-MS/MS runs with ion-trap fragmentation. In order to generate a wide range of peptides, studies covered a broad set of instrument and digestion conditions using multiple sources of HSA and trypsin. Computer methods were developed to enable the reliable identification and reference spectrum extraction of all peptide ions identifiable by current sequence search methods. This process made use of both MS2 (tandem) spectra and MS1 (electrospray) data. Identified spectra were generated for 2918 different peptide ions, using a variety of manually-validated filters to ensure spectrum quality and identification reliability. Shotgun proteomics is a widely used and evolving method for determining the protein composition of a biological mixture (1-3). It most often involves the digestion of denatured proteins by trypsin, followed by the identification of product peptides and the use of this information to infer protein identities and possibly targeted post-translational modifications (PTMs)1 . However, because digestion is a highly complex chemical process, a large proportion of identifiable products are not specifically targeted for analysis and therefore invisible to the analysis. These include unexpected and unwanted peptides that interfere with the analysis. Others may contain modifications of biological origin, which, unless specifically targeted, can be lost among the forest of artifacts (4 -6). This paper describes methods for building a tandem mass spectral library capable of characterizing all identifiable peptides in a tryptic digest of a selected protein. Spectral libraries are known to provide an effective way of reusing this information to quickly, reliably, and sensitively determine peptide identities (7-11). These identifications can serve several purposes, including 1) ensuring that all previously identified peptides are identified regardless of search engine settings, 2) tagging artifact peptides that might otherwise lead to false positive identifications, 3) ensuring the identification of known and identifiable biological post-translational modifications without explicitly looking for them, and 4) providing a list of artifact peptides for assessing the quality of the sample preparation process.HSA, human serum albumin, was selected as the target protein for library development partly because of its ubiquity, making up Ͼ50% of the total protein in blood (12-13) and therefore found in many biological samples, and partly because of the considerable background information available

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“…Methionines were shown to be oxidized by exposure to air during general handling [55][56][57] and even, to a limited extent, by the ionization necessary for MS analysis. 58,59 These reports indicated that artifactual oxidation of methionine caused by common laboratory manipulation could be significant.…”

Section: Scmentioning

confidence: 99%

Applying the tools of chemistry (mass spectrometry and covalent modification by small molecule reagents) to the detection of prions and the study of their structure

Silva

2014

Prion

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Oxidation Artifacts in the Electrospray Mass Spectrometry of Aβ Peptide

Cited by 108 publications

References 32 publications

Formation of unexpected ions from a first‐generation polyamidoamine dendrimer by use of methanol: an artefact due to electrospray emitter corrosion?

Formation of unexpected ions from a first‐generation polyamidoamine dendrimer by use of methanol: an artefact due to electrospray emitter corrosion?

Tandem Mass Spectral Libraries of Peptides in Digests of Individual Proteins: Human Serum Albumin (HSA)

Applying the tools of chemistry (mass spectrometry and covalent modification by small molecule reagents) to the detection of prions and the study of their structure

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