Mass Spectrometry of Gangliosides from Human Sensory and Motor Cortex

2013 ◽  
Vol 66 (7) ◽  
pp. 781 ◽  
Author(s):  
Corina Flangea ◽  
Dragana Fabris ◽  
Željka Vukelić ◽  
Alina D. Zamfir
Keyword(s):  
Mass Spectrometry ◽  
Motor Cortex ◽  
Brain Regions ◽  
Collision Induced Dissociation ◽  
Tandem Ms ◽  
Acetylneuraminic Acid ◽  
Second Stage ◽  
Specific Composition ◽  
The Central Nervous System ◽  
Human Motor

Sialylated glycosphingolipids, known as gangliosides, are highly expressed in the central nervous system exhibiting region-specific composition in correlation to the specialised functions of particular brain regions. In the present study high resolution tandem mass spectrometry on a quadrupole time-of-flight instrument with nanoelectrospray was optimised and applied for the first comparative assessment of the ganglioside profile in single specimens of adult human motor and somatosensory cortex. In the second stage, the structural analysis performed by collision induced dissociation tandem MS disclosed the presence in motor cortex of a fucose-ganglioside Fuc-GM1 (d18 : 1/20 : 0) isomer exhibiting both N-acetylneuraminic acid and fucose residues linked to the inner galactose.

Cobalt-Mediated Decarboxylative Homocoupling of Alkynyl Carboxylic Acids

2014 ◽  
Vol 67 (5) ◽  
pp. 701 ◽  
Author(s):  
Michael G. Leeming ◽  
George N. Khairallah ◽  
Sandra Osburn ◽  
Krista Vikse ◽  
Richard A. J. O'Hair
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Final Stage ◽  
Mononuclear Complex ◽  
Collision Induced Dissociation ◽  
Reductive Coupling ◽  
Second Stage ◽  
Mononuclear Complexes ◽  
Relative Activation ◽  
Bond Homolysis

Cobalt-mediated decarboxylative Glaser-like C–C bond coupling of carboxylates has been studied in the gas phase using collision-induced dissociation (CID) multistage mass spectrometry (MSn) experiments. Both the identity of the carboxylate RCO2– (R = Me, HC≡C, MeC≡C, and PhC≡C) and the nuclearity of the complex ([CoCl(O2CR)2]– versus [Co2Cl3(O2CR)2]–) play a role in the types of reactions observed and their relative activation energies. In the first stage of CID, the mononuclear complex [CoCl(O2CMe)2]– undergoes decarboxylation, while the dinuclear [Co2Cl3(O2CMe)2]– undergoes cluster fission to yield [CoCl3]–; all acetylenic carboxylate complexes [CoCl(O2CR)2]– and [Co2Cl3(O2CR)2]– undergo decarboxylation. Isolation of the decarboxylated products followed by a second stage of CID results in a second decarboxylation event for all systems except for [CoCl(Me)(O2CMe)]–, which undergoes bond homolysis. In the final stage of CID, all acetylenic complexes undergo Glaser coupling, forming reduced Co anions. Overall dinuclear cobalt clusters are superior to mononuclear complexes at promoting decarboxylation and reductive coupling. The order of reactivity among the acetylide ligands is PhC≡C > MeC≡C > HC≡C.

High-resolution mass spectrometry reveals a complex ganglioside pattern and novel polysialylated structures associated with the human motor cortex

2021 ◽  
pp. 146906672110409
Author(s):  
Raluca Ica ◽  
Cristian VA Munteanu ◽  
Zeljka Vukelic ◽  
Alina D Zamfir
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Motor Cortex ◽  
Brain Region ◽  
High Resolution Mass Spectrometry ◽  
Acetate Anion ◽  
Human Motor Cortex ◽  
High Resolution Mass ◽  
Human Motor ◽  
Resolution Mass

We have developed here a superior methodology based on high-resolution mass spectrometry for screening and fragmentation analysis of gangliosides extracted and purified from the human motor cortex . The experiments, conducted on a nanoelectrospray Orbitrap mass spectroscope in the negative ion mode, allowed the discrimination in the native mixture extracted from human motor cortex of no less than 83 different gangliosides, which represents the highest number of structures identified so far in this brain region. The spectral data, acquired in high-resolution mass spectrometry mode with a remarkable sensitivity and an average mass accuracy of 4.48 ppm, also show that the gangliosidome of motor cortex is generally characterized by species exhibiting a much higher degree of sialylation than previously known. Motor cortex was found dominated by complex structures with a sialylation degree ≥3, exhibiting long saccharide chains, in the G1 class. Fucogangliosides and species with the glycan chain elongated by either O-acetylation and/or acetate anion attachments were also detected; the later modification was for the first time discovered in this brain region. Of major significance is the identification of hepta and octasialylated species of GS1 and GO1 type, which are among the structures with the longest oligosaccharide chain discovered so far in the human brain. In the last stage of research, tandem mass spectrometry performed by higher energy collision dissociation provided structural data documenting the occurrence of GT1b (d18:1/20:0) isomer in the human motor cortex.

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