Detection of Adducts with Matrix Clusters in the Positive and Negative Ion Mode MALDI-TOF Mass Spectra of Phospholipids

2009 ◽  
Vol 64 (3) ◽  
pp. 331-334 ◽  
Author(s):  
Marijana Petković ◽  
Jürgen Schiller ◽  
Matthias Müller ◽  
Rosmarie Süß ◽  
Klaus Arnold ◽  
...  
Keyword(s):  
Mass Spectra ◽  
Negative Ion ◽  
Dihydroxybenzoic Acid ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Maldi Tof Mass Spectra ◽  
Negative Ion Mode ◽  
Charged Ions ◽  
Positively Charged ◽  
Tof Ms

It is usually accepted that neutral phospholipids (PLs) generate singly positively charged ions, whereas negative PLs are easily detectable in the negative ion mode when analysed by matrix-assisted laser desorption and ionisation time-offlight mass spectrometry (MALDI-TOF MS). In this study, we demonstrate that some caution is required in the interpretation of MALDI-TOF mass spectra of PLs, since also neutral PLs have appeared to be detectable in the negative ion mode as well. Neutral and negatively charged phospholipids can generate adducts with the most commonly used matrix - 2,5-dihydroxybenzoic acid - yielding singly negatively charged ions that are detectable in the spectra. This further contributes to the complexity of the spectra and potentially leads to severe misinterpretation, particularly when unknown mixtures of PLs are analysed by MALDI-TOF MS.

scholarly journals Characterization of aliphatic hyperbranched polyesters by MALDI-TOF mass spectrometry

2007 ◽  
Vol 61 (6) ◽  
pp. 333-341
Author(s):  
Jasna Vukovic ◽  
Slobodan Jovanovic ◽  
Manfred Lechner
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Degree Of Polymerization ◽  
Side Reactions ◽  
Maldi Tof Ms ◽  
Hyperbranched Polyesters ◽  
Maldi Tof ◽  
Maldi Tof Mass Spectra ◽  
Tof Ms

In this work, MALDI-TOF mass spectrometry was used for the characterization of aliphatic hyperbranched polyesters (AHBP), synthesized from 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) and di-trimethylolpropane. From the obtained results it was concluded that it was not possible to take complete advantages of MALDI-TOF MS in this particular case, since the AHBP used in this work were polydisperse. The intensity of the signals from the high mass tail of these samples (pseudo generation higher than four) was underestimated and insufficient to distinguish it from the baseline and to use it for the analysis of the spectra. As a consequence of that, lower values of the Mn were obtained. At the same time, Mw were also underestimated, which led to very low values of the polydispersity index. On the other hand, it was possible to obtain molar masses of individual molecules from the MALDI-TOF mass spectra of AHBP and to qualitatively determine the extent of cyclization (side reactions) at each degree of polymerization. Using the adequate set of equations and results obtained from MALDI-TOF mass spectra of AHBP, every signal from the spectra was identified. The obtained results show that formation of poly(bis-MPA), intramolecular esterification and intramolecular etherification occurred as side reactions during the synthesis of these polyesters. The relative amount of the cycles increases with the number of pseudo generation (from the second up to the fifth pseudo generation). It was also observed that the relative proportion of the signals which represent cyclic structures increases with the increasing degree of polymerization. In this work the basic principles of MALDI-TOF MS are also presented, as well as, a review of adequate published articles.

scholarly journals Conserved mass peaks in MALDI-TOF mass spectra of bacterial species at the genus and species levels

2018 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Mass Spectrum ◽  
Mass Spectra ◽  
Mass Peak ◽  
Biological Basis ◽  
Maldi Tof Ms ◽  
Microbial Identification ◽  
Genus Level ◽  
Maldi Tof ◽  
Maldi Tof Mass Spectra ◽  
Tof Ms

Microbes are identified based on their distinguishing characteristics such as gene sequence or metabolic profile. Nucleic acid approaches such as 16S rRNA gene sequencing provide the gold standard method for microbial identification in the contemporary era. However, mass spectrometry-based microbial identification is gaining credence through ease of use, speed, and reliability. Specifically, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been used in identifying bacteria, fungus, molds and archaea to the species level with high accuracy. The approach relies on the existence of unique mass spectrum fingerprint for individual microbial species. By comparing the mass spectrum of an unknown microbe with that catalogued in a reference database of known microorganisms, microbes could be identified through mass spectrum fingerprinting. However, the approach lacks fundamental biological basis given the relative difficulty in assigning specific protein to particular mass peak in the profiled mass spectrum, which hampers a deeper understanding of the mass spectrum obtained. This study seeks to examine the existence of conserved mass peaks in MALDI-TOF mass spectra of bacteria at the species and genus levels using open access data from SpectraBank. Results revealed that conserved mass peaks existed for all bacterial species examined. Large number of conserved mass peaks such as that of Escherichia coli and Morganella morganii suggested more closely-related strains of a species though functional annotation of the mass peaks is required to provide a deeper understanding of the mechanisms underlying the conservation of specific proteins. On the other hand, strains of Staphylococcus aureus and Pseudomonas putida had the least number of conserved mass peaks. Presence of conserved mass peaks in many genus provided further evidence that MALDI-TOF MS microbial identification had a biological basis in identification of microbial species to the genus level. In addition, it also highlighted that a subset of proteins could define the taxonomical boundary between the species and genus level. Finally, existence of only one conserved mass peak in Bacillus genus corroborated the difficulty of discriminating Bacillus species based on MALDI-TOF mass spectra. Similarly, no conserved mass peak at the genus level could be found for the Staphylococcus genus. Overall, existence of conserved mass peaks of bacteria at the species and genus levels provided evidence of a firm biological basis in the mass spectrum fingerprinting approach of MALDI-TOF MS microbial identification. This could help identify specific species in mass spectrum of single or multiple microbial species. Further functional annotation of the conserved mass peaks could illuminate in greater detail the biological mysteries of why certain proteins are conserved in specific genus and species.

scholarly journals Conserved mass peaks in MALDI-TOF mass spectra of bacterial species at the genus and species levels

2018 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Mass Spectrum ◽  
Mass Spectra ◽  
Mass Peak ◽  
Biological Basis ◽  
Maldi Tof Ms ◽  
Microbial Identification ◽  
Genus Level ◽  
Maldi Tof ◽  
Maldi Tof Mass Spectra ◽  
Tof Ms

Microbes are identified based on their distinguishing characteristics such as gene sequence or metabolic profile. Nucleic acid approaches such as 16S rRNA gene sequencing provide the gold standard method for microbial identification in the contemporary era. However, mass spectrometry-based microbial identification is gaining credence through ease of use, speed, and reliability. Specifically, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been used in identifying bacteria, fungus, molds and archaea to the species level with high accuracy. The approach relies on the existence of unique mass spectrum fingerprint for individual microbial species. By comparing the mass spectrum of an unknown microbe with that catalogued in a reference database of known microorganisms, microbes could be identified through mass spectrum fingerprinting. However, the approach lacks fundamental biological basis given the relative difficulty in assigning specific protein to particular mass peak in the profiled mass spectrum, which hampers a deeper understanding of the mass spectrum obtained. This study seeks to examine the existence of conserved mass peaks in MALDI-TOF mass spectra of bacteria at the species and genus levels using open access data from SpectraBank. Results revealed that conserved mass peaks existed for all bacterial species examined. Large number of conserved mass peaks such as that of Escherichia coli and Morganella morganii suggested more closely-related strains of a species though functional annotation of the mass peaks is required to provide a deeper understanding of the mechanisms underlying the conservation of specific proteins. On the other hand, strains of Staphylococcus aureus and Pseudomonas putida had the least number of conserved mass peaks. Presence of conserved mass peaks in many genus provided further evidence that MALDI-TOF MS microbial identification had a biological basis in identification of microbial species to the genus level. In addition, it also highlighted that a subset of proteins could define the taxonomical boundary between the species and genus level. Finally, existence of only one conserved mass peak in Bacillus genus corroborated the difficulty of discriminating Bacillus species based on MALDI-TOF mass spectra. Similarly, no conserved mass peak at the genus level could be found for the Staphylococcus genus. Overall, existence of conserved mass peaks of bacteria at the species and genus levels provided evidence of a firm biological basis in the mass spectrum fingerprinting approach of MALDI-TOF MS microbial identification. This could help identify specific species in mass spectrum of single or multiple microbial species. Further functional annotation of the conserved mass peaks could illuminate in greater detail the biological mysteries of why certain proteins are conserved in specific genus and species.

scholarly journals Conserved mass peaks in MALDI-TOF mass spectra of bacterial species

2018 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Mass Spectrum ◽  
Mass Spectra ◽  
Bacterial Species ◽  
Biological Basis ◽  
Maldi Tof Ms ◽  
Microbial Identification ◽  
Microbial Species ◽  
Maldi Tof ◽  
Maldi Tof Mass Spectra ◽  
Tof Ms

Microbes are identified based on their distinguishing characteristics such as gene sequence or metabolic profile. Nucleic acid approaches such as 16S rRNA gene sequencing provide the gold standard method for microbial identification in the contemporary era. However, mass spectrometry-based microbial identification is gaining credence through ease of use, speed, and reliability. Specifically, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been used in identifying bacteria, fungus, molds and archaea to the species level with high accuracy. The approach relies on the existence of unique mass spectrum fingerprint for individual microbial species. By comparing the mass spectrum of an unknown microbe with that catalogued in a reference database of known microorganisms, microbes could be identified through mass spectrum fingerprinting. However, the approach lacks fundamental biological basis given the relative difficulty in assigning specific protein to particular mass peak in the profiled mass spectrum, which hampers a deeper understanding of the mass spectrum obtained. This study seeks to examine the existence of conserved mass peaks in MALDI-TOF mass spectra of bacterial strains belonging to the same species in open access data from SpectraBank. Results revealed that conserved mass peaks existed for all bacterial species examined (Bacillus subtilis, Bacillus thuringiensis, Carnobacterium maltaaromaticum, Escherichia coli, Proteus vulgaris, Pseudomonas fluorescens, Pseudomonas fragi, Pseudomonas putida, Pseudomonas syringae, Serratia marcescens, Serratia proteamaculans, Staphylococcus aureus, and Stenotrophomonas maltophilia). Large number of conserved mass peaks such as that of E. coli might suggest more closely-related strains of a species though functional annotation of the mass peaks is required to provide deeper understanding of the mechanisms underlying the conservation of specific proteins. On the other hand, strains of S. aureus and P. putida had the least number of conserved mass peaks. Presence of conserved mass peaks in the genus Pseudomonas and Serratia provided further evidence that MALDI-TOF MS microbial identification had a biological basis in identification of microbial species to the genus level. On the other hand, it also highlighted that a subset of proteins could define the taxonomical boundary between the species and genus level. Overall, existence of conserved mass peaks in strains of the same bacterial species provided evidence of a firm biological basis in the mass spectrum fingerprinting approach of MALDI-TOF MS microbial identification. This could help identify specific species in mass spectrum of single or multiple microbial species. Further functional annotation of the conserved mass peaks could illuminate in greater detail the biological mysteries of why certain proteins are conserved in specific genus and species.

scholarly journals Enhanced MALDI-TOF MS Analysis of Phosphopeptides Using an Optimized DHAP/DAHC Matrix

2010 ◽  
Vol 2010 ◽  
pp. 1-12 ◽  
Author(s):  
Junjie Hou ◽  
Zhensheng Xie ◽  
Peng Xue ◽  
Ziyou Cui ◽  
Xiulan Chen ◽  
...  
Keyword(s):  
Effective Means ◽  
Negative Ion ◽  
Phosphorylation Sites ◽  
Measurement Sensitivity ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Flight Mass Spectrometry ◽  
Phosphorylated Peptides ◽  
Negative Ion Mode ◽  
Tof Ms

Selecting an appropriate matrix solution is one of the most effective means of increasing the ionization efficiency of phosphopeptides in matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). In this study, we systematically assessed matrix combinations of 2, 6-dihydroxyacetophenone (DHAP) and diammonium hydrogen citrate (DAHC), and demonstrated that the low ratio DHAP/DAHC matrix was more effective in enhancing the ionization of phosphopeptides. Low femtomole level of phosphopeptides from the tryptic digests ofα-casein andβ-casein was readily detected by MALDI-TOF-MS in both positive and negative ion mode without desalination or phosphopeptide enrichment. Compared with the DHB/PA matrix, the optimized DHAP/DAHC matrix yielded superior sample homogeneity and higher phosphopeptide measurement sensitivity, particularly when multiple phosphorylated peptides were assessed. Finally, the DHAP/DAHC matrix was applied to identify phosphorylation sites fromα-casein andβ-casein and to characterize two phosphorylation sites from the human histone H1 treated with Cyclin-Dependent Kinase-1 (CDK1) by MALDI-TOF/TOF MS.

scholarly journals N-(1-Naphthyl) Ethylenediamine Dinitrate: A New Matrix for Negative Ion MALDI-TOF MS Analysis of Small Molecules

2012 ◽  
Vol 23 (9) ◽  
pp. 1454-1460 ◽  
Author(s):  
Rui Chen ◽  
Suming Chen ◽  
Caiqiao Xiong ◽  
Xunlei Ding ◽  
Chih-Che Wu ◽  
...  
Keyword(s):  
Small Molecules ◽  
Negative Ion ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Ms Analysis ◽  
Tof Ms

scholarly journals Development and Validation of an in-House Library of Colombian Candida auris Strains with MALDI-TOF MS to Improve Yeast Identification

2020 ◽  
Vol 6 (2) ◽  
pp. 72 ◽  
Author(s):  
Andrés Ceballos-Garzon ◽  
Daniela Amado ◽  
Norida Vélez ◽  
María José Jiménez-A ◽  
Crescencio Rodríguez ◽  
...  
Keyword(s):  
Mass Spectra ◽  
Candida Auris ◽  
Yeast Identification ◽  
Great Opportunity ◽  
Maldi Tof Ms ◽  
Identification Process ◽  
Clinical Strains ◽  
Maldi Tof ◽  
Development And Validation ◽  
Tof Ms

Background: Candida auris is characterized for having a high genetic variability among species. MALDI-TOF MS library contains spectra from only three strains of C. auris, which makes difficult the identification process and gives low scores at the species level. Our aim was to construct and validate an internal library to improve C. auris identification with Colombian clinical strains. Methods: From 30 clinical strains, 770 mass spectra were obtained for the construction of the database. The validation was performed with 300 strains to compare the identification results in the BDAL and C. auris Colombia libraries. Results: Our library allowed a complete, 100% identification of the evaluated strains and a significant improvement in the scores obtained, showing a better performance compared to the Bruker BDAL library. Conclusions: The strengthening of the database is a great opportunity to improve the scoring and C. auris identification. Library data are available via ProteomeXchange with identifier PXD016387.

Phosphatidylcholines and -ethanolamines can be easily mistaken in phospholipid mixtures: a negative ion MALDI-TOF MS study with 9-aminoacridine as matrix and egg yolk as selected example

2009 ◽  
Vol 395 (8) ◽  
pp. 2479-2487 ◽  
Author(s):  
Beate Fuchs ◽  
Annabell Bischoff ◽  
Rosmarie Süß ◽  
Kristin Teuber ◽  
Martin Schürenberg ◽  
...  
Keyword(s):  
Egg Yolk ◽  
Negative Ion ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Tof Ms

scholarly journals Comparison of MALDI-TOF mass spectra of [PdCl(dien)]Cl and [Ru(en)2Cl2]Cl acquired with different matrices

2011 ◽  
Vol 76 (12) ◽  
pp. 1687-1701 ◽  
Author(s):  
Bojana Damnjanovic ◽  
Biljana Petrovic ◽  
Jasmina Dimitric-Markovic ◽  
Marijana Petkovic
Keyword(s):  
Transition Metal Complexes ◽  
Mass Spectra ◽  
Hydroxycinnamic Acid ◽  
Dihydroxybenzoic Acid ◽  
Ionization Time ◽  
Maldi Tof ◽  
Ru Complex ◽  
Maldi Tof Mass Spectra ◽  
The Matrix ◽  
Flavonoid Quercetin

In this work, the matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectra of two cationic complexes, i.e., [PdCl(dien)]Cl and [Ru(en)2Cl2]Cl, acquired under different conditions were analyzed. The spectra were recorded with three matrices with or without trifluoroacetic acid (TFA), i.e., two traditional matrices, i.e., 2,5-dihydroxybenzoic acid and ?-cyano-hydroxycinnamic acid, and one flavonoid, quercetin. The spectra acquired with quercetin appeared to be the simplest, whereas in the spectra obtained with other matrices, peaks arising either from the addition of matrix molecules or from the fragmentation products were detectable. Addition of TFA did not complicate the spectra of the Pd(II) and Ru(III) complexes when the traditional matrices were used. On the other hand, the spectra of Pd complex were simpler, whereas the addition of TFA in the case of the Ru complex resulted in a higher number of peaks, some of which could not be identified. Taken together, the results of this study once more emphasize the differences arising in the MALDI-TOF mass spectra of transition metal complexes in dependence on the applied matrix.

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