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.

Study on the Structure of Mangrove Polyflavonoid Tannins with MALDI-TOF Mass Spectrometry and NMR

2012 ◽  
Vol 554-556 ◽  
pp. 1988-1993 ◽  
Author(s):  
Liang Liang Zhang ◽  
Yong Mei Wang ◽  
Dong Mei Wu ◽  
Man Xu ◽  
Jia Hong Chen
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Degree Of Polymerization ◽  
Epicatechin Gallate ◽  
Mangrove Species ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Rhizophora Apiculata ◽  
13C Nuclear Magnetic Resonance ◽  
Tof Ms

The properties of polyflavonoid tannins from the mangrove species depend on their structure in terms of monomer units, their mean degree of polymerization and the linkage-type between flavan-3-ol units with a considerable range of structural variation. Polyflavonoid tannins were characterized by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS), which were too difficult to be resolved by other techniques. MALDI-TOF mass spectra of polyflavonoid tannins of four mangrove species in Rhizophoraceae, Kandelia candel, Ceriops tagal, Bruguiera cylindrica and Rhizophora apiculata showed as follows: (1) procyanidin oligomers formed by catechin/epicatechin, and catechin-3-O-rhamnoside monomers were present in great proportions; epigallocatechin and epicatechin gallate monomers were not detected; (2) the doubly linked structure of A-type procyanidins were also evident from the mass spectra of K. candel; (3) there were major differences in polyflavonoid tannin structure among mangrove species; and (4) the distribution of tannin oligomers, and the number-average degree of polymerization obtained by MALDI-TOF MS appeared to compare well with the results obtained by 13C nuclear magnetic resonance (NMR) analysis.

scholarly journals Understanding the chemical basis for the preferential ionization of specific biomolecules in mass spectrometry analysis of microbial cells

2019 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Mass Spectrometry Analysis ◽  
Chemical Pretreatment ◽  
Maldi Tof Ms ◽  
Spectrometry Analysis ◽  
Chemical Basis ◽  
Maldi Tof ◽  
Different Types ◽  
Tof Ms

Mass spectrometry-enabled microbial identification has successfully demonstrated the feasibility of using profiled biomolecules for identifying microorganisms based on a chemometric or proteome database search approach. However, mechanisms driving the preferential ionization and detection of particular biomolecules in various types of mass spectrometry remain poorly understood. Specifically, mass spectra obtained from different microbial species remain poorly annotated with respect to the specific types of biomolecules accounting for the peaks. For example, while ribosomal proteins are known to be a significant class of biomolecules that could partially account for the profiled mass peaks in mass spectra of microorganisms, other classes of proteins and biomolecules remain poorly annotated. This raises the important question of how different mass spectrometry approaches ionize different types of biomolecules from a cellular matrix. Specifically, mass spectra of microorganisms reveal that only a couple of mass peaks could capture the phylogeny of a species. However, the proteome of a cell is much larger and more complicated, and yet is not fully profiled by different types of mass spectrometry methods. For example, electrospray ionization mass spectrometry (ESI-MS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) could only provide a small snapshot of the entire bacterial proteome. It could be argued that different mass spectrometry methods provide complementary views of a particular proteome. However, the question remains, how do proteins and biomolecules interact with the different sample preparation and mass spectrometry analysis methods for generating an ion cloud for separation in a mass spectrometer? Thus, efforts could be directed towards understanding how different types of proteins could be preferentially ionized by MALDI-TOF MS. Specifically, different reagents could be used to perform chemical pretreatment on the proteome, which would subsequently be analyzed by mass spectrometry. Thus, a correlative map between types of chemical pretreatment used and the corresponding mass spectra could be obtained. Collectively, knowledge gleaned from the research would illuminate the chemical basis by which specific biomolecules are preferentially ionized under particular conditions, which would inform the development of strategies for increasing the subset of biomolecules ionized from a cellular proteome. Such chemical rules would also aid in the interpretation of mass spectra obtained, particularly in understanding the biological context of the experiment. Overall, the key goal of this research is to help answer the question: what is the biological basis and context of the mass spectrum obtained from cells?

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 A novel and rapid approach to yeast differentiation using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry

2003 ◽  
Vol 17 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Richard E. Sherburn ◽  
Richard O. Jenkins
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Time Of Flight ◽  
Laser Desorption ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Flight Mass Spectrometry ◽  
Tof Ms ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

Matrix-assisted laser desorption/ionisation time of flight mass spectrometry (MALDI-TOF-MS) was investigated as a method for the rapid identification of yeast cells. Following pretreatment of yeast samples with a cell wall digesting enzyme (lyticase), distinct and reproducible mass spectra over them/zrange 2,000 to 16,000 were obtained by MALDI-TOF-MS. Using an optimised procedure, characteristic mass spectra that distinguished between Candida spp. and between strains of Saccharomyces cerevisiae were produced. The approach offers the potential for rapid differentiation of yeasts in clinical diagnosis and in the fermentation industries.

Investigation of MALDI-TOF Mass Spectrometry of Diverse Synthetic Metalloporphyrins, Phthalocyanines and Multiporphyrin Arrays

1999 ◽  
Vol 03 (04) ◽  
pp. 283-291 ◽  
Author(s):  
N. SRINIVASAN ◽  
CAROL A. HANEY ◽  
JONATHAN S. LINDSEY ◽  
WENZHU ZHANG ◽  
BRIAN T. CHAIT
Keyword(s):  
Mass Spectrometry ◽  
Negative Ion ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Flight Mass Spectrometry ◽  
Powerful Analytical Tool ◽  
Molecular Masses ◽  
Dominant Process ◽  
Tof Ms

We investigated the utility of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for analyzing porphyrinic compounds using a variety of different synthetic porphyrins, azaporphyrins, phthalocyanines and multiporphyrin arrays. Comparisons of spectra obtained from these analytes deposited either as neat samples or codeposited with neutral or acidic matrices have been made with the goal of identifying conditions that yield minimal demetalation, transmetalation, adduct formation and fragmentation. It was found that the molecular masses of many porphyrins can be successfully measured from neat sample preparations and do not require a matrix to facilitate desorption and ionization, although the measurement of large multiporphyrin arrays was facilitated by the use of matrices. Demetalation of magnesium porphyrins occurred in the presence of acidic matrices, but not with neutral matrices such as 1,4-benzoquinone. Positive ion spectra were obtained for each compound and negative ion spectra were also collected for the azaporphyrins and phthalocyanines. Examination of selected samples (prepared neat, with 1,4-benzoquinone, 2,3,5,6-tetrachloro-1,4-benzoquinone or α-cyano-4-hydroxycinnamic acid) showed that the dominant process of ionization involved oxidation yielding the radical cation M+· rather than the protonated molecule [M+H]+. MALDI-TOF-MS is shown to be a powerful analytical tool for the characterization of diverse synthetic porphyrinic compounds.

scholarly journals Discrimination of Bacillus cereus Group Members by MALDI-TOF Mass Spectrometry

2021 ◽  
Vol 9 (6) ◽  
pp. 1202
Author(s):  
Viviana Manzulli ◽  
Valeria Rondinone ◽  
Alessandro Buchicchio ◽  
Luigina Serrecchia ◽  
Dora Cipolletta ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Bacillus Cereus ◽  
Mass Spectra ◽  
Critical Time ◽  
Principal Component ◽  
Etiologic Agent ◽  
Bacillus Cereus Group ◽  
Maldi Tof Ms ◽  
Maldi Tof ◽  
Tof Ms

Matrix-Assisted Laser Desorption/Ionization Time Of Flight Mass Spectrometry (MALDI-TOF MS) technology is currently increasingly used in diagnostic laboratories as a cost effective, rapid and reliable routine technique for the identification and typing of microorganisms. In this study, we used MALDI-TOF MS to analyze a collection of 160 strains belonging to the Bacillus cereus group (57 B. anthracis, 49 B. cereus, 1 B. mycoides, 18 B. wiedmannii, 27 B. thuringiensis, 7 B. toyonensis and 1 B. weihenstephanensis) and to detect specific biomarkers which would allow an unequivocal identification. The Main Spectra Profiles (MSPs) were added to an in-house reference library, expanding the current commercial library which does not include B. toyonensis and B. wiedmannii mass spectra. The obtained mass spectra were statistically compared by Principal Component Analysis (PCA) that revealed seven different clusters. Moreover, for the identification purpose, were generated dedicate algorithms for a rapid and automatic detection of characteristic ion peaks after the mass spectra acquisition. The presence of specific biomarkers can be used to differentiate strains within the B. cereus group and to make a reliable identification of Bacillus anthracis, etiologic agent of anthrax, which is the most pathogenic and feared bacterium of the group. This could offer a critical time advantage for the diagnosis and for the clinical management of human anthrax even in case of bioterror attacks.

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 Understanding the chemical basis for the preferential ionization of specific biomolecules in mass spectrometry analysis of microbial cells

2019 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Mass Spectrometry Analysis ◽  
Chemical Pretreatment ◽  
Maldi Tof Ms ◽  
Spectrometry Analysis ◽  
Chemical Basis ◽  
Maldi Tof ◽  
Different Types ◽  
Tof Ms

Mass spectrometry-enabled microbial identification has successfully demonstrated the feasibility of using profiled biomolecules for identifying microorganisms based on a chemometric or proteome database search approach. However, mechanisms driving the preferential ionization and detection of particular biomolecules in various types of mass spectrometry remain poorly understood. Specifically, mass spectra obtained from different microbial species remain poorly annotated with respect to the specific types of biomolecules accounting for the peaks. For example, while ribosomal proteins are known to be a significant class of biomolecules that could partially account for the profiled mass peaks in mass spectra of microorganisms, other classes of proteins and biomolecules remain poorly annotated. This raises the important question of how different mass spectrometry approaches ionize different types of biomolecules from a cellular matrix. Specifically, mass spectra of microorganisms reveal that only a couple of mass peaks could capture the phylogeny of a species. However, the proteome of a cell is much larger and more complicated, and yet is not fully profiled by different types of mass spectrometry methods. For example, electrospray ionization mass spectrometry (ESI-MS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) could only provide a small snapshot of the entire bacterial proteome. It could be argued that different mass spectrometry methods provide complementary views of a particular proteome. However, the question remains, how do proteins and biomolecules interact with the different sample preparation and mass spectrometry analysis methods for generating an ion cloud for separation in a mass spectrometer? Thus, efforts could be directed towards understanding how different types of proteins could be preferentially ionized by MALDI-TOF MS. Specifically, different reagents could be used to perform chemical pretreatment on the proteome, which would subsequently be analyzed by mass spectrometry. Thus, a correlative map between types of chemical pretreatment used and the corresponding mass spectra could be obtained. Collectively, knowledge gleaned from the research would illuminate the chemical basis by which specific biomolecules are preferentially ionized under particular conditions, which would inform the development of strategies for increasing the subset of biomolecules ionized from a cellular proteome. Such chemical rules would also aid in the interpretation of mass spectra obtained, particularly in understanding the biological context of the experiment. Overall, the key goal of this research is to help answer the question: what is the biological basis and context of the mass spectrum obtained from cells?

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.

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