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Dopamine and iron mediated fragmentation of galactocerebroside and cardiolipin in micelles

100%
Yurkova I., Kisel M., Arnhold J., Shadyro O.
Open Chemistry
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2007
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vol. 5
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issue 4
970-980
EN
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and thin-layer chromatography (TLC) have been used to study dopamine and iron mediated free-radical transformation of lipids in their hydrophilic parts. It has been shown that the action of the dopamine/Fe2+ system on galactocerebroside or cardiolipin, which are the components of mixed micelles, results in formation of ceramide or phosphatidic acid and phosphatidylhydroxyacetone, respectively. These data, when combined with results obtained using the ascorbate/Fe2+/H2O2 oxidizing system with the same substrates, demonstrate that the formation of these products proceeds via an OH-radical induced fragmentation taking place in polar moiety of the starting lipids. [...]
2
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Identification of Bacillus spp. colonizing the nasal mucosa of healthy adults living in the suburban area using the matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS) system

100%
Kosikowska U., Stepien-Pysniak D., Ozga D., Wernicki A., Malm A.
Current Issues in Pharmacy and Medical Sciences
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2014
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vol. 27
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issue 3
137-141
EN
Bacillus spp. can be regarded as a rare component of the nasal mucosa microflora. The aim of this study was to identify Bacillus spp. from the nasal mucosa of healthy adults living in the suburban area near Lublin using the matrix-assisted laser desorptionionization time-of-flight mass spectrometry (MALDI-TOF MS) system. A total of 11 bacterial isolates from the nasal specimens were cultured. The following species were identified using the routine microbiological methods: Staphylococcus aureus (3 isolates), S. epidermidis (1 isolate), S. intermedius (1 isolate) and Staphylococcus spp. (1 isolate). Moreover, 2 strains of Escherichia coli were isolated. Besides, 3 isolates of Bacillus spp. were found. These isolates were characterized by means of MALDI-TOF MS, resulting in highly specific mass spectral fingerprints and these were identified as B. pumilus, B. safenis and B. licheniformis. It was observed that all studied Bacillus spp. isolates only had the masses in common at 3864 ± 2, 7727 ± 2, and 14301 ± 4. The spectra of B. safensis and B. pumilus showed peaks at m/z 4914 ± 3, 6621 ± 3 and 14291 ± 2, which were absent in the spectrum of B. licheniformis. For B. safenis and B. pumilus, other potential biomarkers could be found at m/z 12620 and 16668, respectively.
3
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Investigation of asparagine deamidation in a SOD1-based biosynthetic human insulin precursor by MALDI-TOF mass spectrometry

88%
Bierczyńska-Krzysik A., Łopaciuk M., Pawlak-Morka R., Stadnik D.
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2014
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vol. 61
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issue 2
349-357
EN
A biosynthetic human insulin precursor displayed enhanced susceptibility to deamidation at one particular site. The present study was undertaken to monitor progress of precursor deamidation at successive manufacturing stages. MALDI-TOF/TOF MS in combination with controlled endoproteinase Glu-C and endoproteinase Asp-N proteolysis was used for rapid and unambiguous determination of deamidated residue within the investigated structure. Close inspection of isotopic distribution patterns of peptides resulting from enzymatic digestion enabled determination of distinct precursor forms occurring during the production process. Asn, Asp, isoAsp and succinimide derivatives of the amino acid at position 26 were unambiguously identified. These modifications are related to the leader peptide of a precursor encompassing amino acid sequence corresponding to that of superoxide dismutase [Cu-Zn] (SOD1 1, EC=1.15.1.1). Monitoring of precursor deamidation process at successive manufacturing stages revealed that the protein folding stage was sufficient for a prominent replacement of asparagine by aspartic and isoaspartic acid and the deamidated human insulin precursor constituted the main manufactured product. Conversion proceeded through a succinimide intermediate. Significant deamidation is associated with the presence of SNG motif and confirms results achieved previously on model peptides. Our findings highlight an essential role of the specific amino acid sequence on accelerated rate of protein deamidation. To our knowledge, this is the first time that such a dramatic change in the relative abundance of Asp and isoAsp resulting from protein deamidation process is reported.
4
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Bacterial species identification

51%
Kshikhundo R., Itumhelo S.
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EN
The traditional methods of bacterial identification are based on observation of either the morphology of single cells or colony characteristics. However, the adoption of newer and automated methods offers advantage in terms of rapid and reliable identification of bacterial species. The review provides a comprehensive appreciation of new and improved technologies such fatty acid profiling, sequence analysis of the 16S rRNA gene, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF), metabolic finger profiling using BIOLOG, ribotyping, together with the computational tools employed for querying the databases that are associated with these identification tools and high throughput genomic sequencing in bacterial identification. It is evident that with the increase in the adoption of new technologies, bacterial identification is becoming easier.
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