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High resolution mass spectrometric characterization of amino linked oligosaccharides - a preliminary study

100%
Ghiulai R., Galusca M., Sisu I., Sisu E., Zamfir A.
Open Chemistry
|
2013
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vol. 11
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issue 8
1309-1319
EN
In this study maltose, maltotriose and maltotetraose were for the first time, coupled to 4,4′-methylenedianiline (MDA). The aim of this preliminary work was to test the feasibility of oligo- and polysaccharide coupling to MDA and the characterization of the coupling products by high resolution mass spectrometry (MS). (+) nanoESI in combination with a quadrupole time of flight (QTOF) MS in full scan (MS) and MS/MS was optimized first on underivatized maltose, maltotriose and maltotetraose. The optimal screening and sequencing conditions were further applied to the MDA-functionalized oligosaccharides. The obtained results revealed a straightforward MS detection of the functionalized oligomers, high sequence coverage and a fragmentation pathway with the formation of B and Y ions as well as the complementary C and Z ions along with a typical cleavage of the aglycon. We consider that this methodology is fully applicable also to polydisperse mixtures of long chain polysaccharides, which due to the large number of components and their size require a systematic method of development and testing. [...]
2
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Discrimination of GalNAc (4S/6S) sulfation sites in chondroitin sulfate disaccharides by chip-based nanoelectrospray multistage mass spectrometry

86%
Flangea C., Serb A., Schiopu C., Tudor S., Sisu E., Seidler D., Zamfir A.
Open Chemistry
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2009
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vol. 7
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issue 4
752-759
EN
Sulfation pattern within chondroitin sulfate (CS) glycosaminoglycan (GAG) chains is an important post-translational modification that regulates their interaction with proteins. In this context, development of highly efficient and reproducible analytical methods for the investigation of CS sulfation patterns is of high necessity. In this study we report a novel method for straightforward determination of N-acetylgalactosamine (GalNAc) sulfation sites in chondroitin sulfate disaccharides. Our protocol involves combining fully automated chip-based nanoelectrospray (nanoESI) for analyte infusion and ionization in negative ion mode with multistage (MSn) collision-induced dissociation (CID) high capacity ion trap (HCT) mass spectrometry for generation of sequence ions diagnostic for identification of sulfate ester group position within GalNAc residues. The feasibility of this approach is here demonstrated on chondroitin 6-O-sulfate and chondroitin 4-O-sulfate disaccharides. Fragmentation patterns obtained by MS2 and MS3 sequencing stages provided first mass spectrometric data from which sulfation site(s) within GalNAc monosaccharide ring could be unequivocally deciphered. Hence, the method allowed discriminating 4S/6S sulfation sites solely on the basis of MS and multistage MS evidence. [...]
3
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Fully automated chip-based nanoelectrospray combined with electron transfer dissociation for high throughput top-down proteomics

86%
Flangea C., Schiopu C., Capitan F., Mosoarca C., Manea M., Sisu E., Zamfir A.
Open Chemistry
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2013
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vol. 11
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issue 1
25-34
EN
The conventional protocol for protein identification by electrospray ionization mass spectrometry (MS) is based on enzymatic digestion which renders peptides to be analyzed by liquid chromatography-MS and collision-induced dissociation (CID) multistage MS, in the so-called bottom-up approach. Though this method has brought a significant progress to the field, many limitations, among which, the low throughput and impossibility to characterize in detail posttranslational modifications in terms of site(s) and structure, were reported. Therefore, the research is presently focused on the development of procedures for efficient top-down fragmentation of intact protein ions. In this context, we developed here an approach combining fully automated chip-based-nanoelectrospray ionisation (nanoESI), performed on a NanoMate robot, with electron transfer dissociation (ETD) for peptide and top-down protein sequencing and identification. This advanced analytical platform, integrating robotics, microfluidics technology, ETD and alternate ETD/CID, was tested and found ideally suitable for structural investigation of peptides and modified/functionalized peptides as well as for top-down analysis of medium size proteins by tandem MS experiments of significantly increased throughput and sensitivity. The obtained results indicate that NanoMate-ETD and ETD/CID may represent a viable alternative to the current MS strategies, with potential to develop into a method of routine use for high throughput top-down proteomics.
4
Content available remote

Synthesis and structural characterization of amino-functionalized polysaccharides

73%
Sisu I., Udrescu V., Flangea C., Tudor S., Dinca N., Rusnac L., Zamfir A., Sisu E.
Open Chemistry
|
2009
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vol. 7
|
issue 1
66-73
EN
A variety of carbohydrates, in particular polysaccharides can be subjected to chemical modification to obtain derivatives with amphiphilic properties, which enable biochemical or biological reactions at the polymer surface. In the present work, a polydisperse maltodextrin mixture of average molecular weight 3000 was coupled with 1,6-hexamethylenediamine (HMD) via reductive amination reaction. Resulting products were characterized by thermal analysis and positive nanoelectrospray quadrupole time-of-flight (Q-TOF) mass spectrometry (MS) and tandem mass spectrometry (MS/MS). Both thermal analysis and MS screening confirmed the formation of the HMD-polysaccharide coupling products. Moreover, HMD-linked polysaccharide chains containing 2 to 26 glucose building blocks were identified by nanoESI Q-TOF MS. MS/MS fragmentation using collision-induced dissociation (CID) at low ion acceleration energies provided strong evidence for HMD-maltodextrin linkage formation and the set of sequence ions diagnostic for the composition and structure of a HMD-linked chain containing 18 glucose residues. [...]
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