scholarly journals Enzymatic Synthesis of Trideuterated Sialosides

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1368 ◽  
Author(s):  
Zhi-P. Cai ◽  
Louis Conway ◽  
Ying Huang ◽  
Wen Wang ◽  
Pedro Laborda ◽  
...  

Sialic acids are a family of acidic monosaccharides often found on the termini of cell surface proteins or lipid glycoconjugates of higher animals. Herein we describe the enzymatic synthesis of the two isotopically labeled sialic acid derivatives d3-X-Gal-α-2,3-Neu5Ac and d3-X-Gal-α-2,3-Neu5Gc. Using deuterium oxide as the reaction solvent, deuterium atoms could be successfully introduced during the enzymatic epimerization and aldol addition reactions when the sialosides were generated. NMR and mass spectrometric analyses confirmed that the resulting sialosides were indeed tri-deuterated. These compounds may be of interest as internal standards in liquid chromatography/mass spectrometric assays for biochemical or clinical studies of sialic acids. This was further exemplified by the use of this tri-deuterated sialosides as internal standards for the quantification of sialic acids in meat and egg samples.

Author(s):  
Watt W. Webb

Plasma membrane heterogeneity is implicit in the existence of specialized cell surface organelles which are necessary for cellular function; coated pits, post and pre-synaptic terminals, microvillae, caveolae, tight junctions, focal contacts and endothelial polarization are examples. The persistence of these discrete molecular aggregates depends on localized restraint of the constituent molecules within specific domaines in the cell surface by strong intermolecular bonds and/or anchorage to extended cytoskeleton. The observed plasticity of many of organelles and the dynamical modulation of domaines induced by cellular signaling evidence evanescent intermolecular interactions even in conspicuous aggregates. There is also strong evidence that universal restraints on the mobility of cell surface proteins persist virtually everywhere in cell surfaces, not only in the discrete organelles. Diffusion of cell surface proteins is slowed by several orders of magnitude relative to corresponding protein diffusion coefficients in isolated lipid membranes as has been determined by various ensemble average methods of measurement such as fluorescence photobleaching recovery(FPR).


2020 ◽  
Vol 36 (6) ◽  
pp. 35-48
Author(s):  
D.V. Коchkin ◽  
G.I. Sobolkovа ◽  
А.А. Fоmеnkov ◽  
R.А. Sidorov ◽  
А.М. Nоsоv

The physiological characteristics of the callus cell cultures of Alhagi persarum Boiss et Buhse, a member of the legume family, widely used in folk medicine, have been studied. It was shown that the source of the explant was an important factor in the initiation of callusogenesis: more intense callusogenesis (almost 100%) was observed for explants from various organs of sterile seedlings, rather than intact plants (less than 30%). As a result, more than 20 lines of morphologically different callus cell cultures were obtained, and the growth parameters for the 5 most intensively growing lines were determined. The composition of fatty acids (FA) of total lipids and secondary metabolites in the most physiologically stable callus line Aр-207 was analyzed. Using capillary gas-liquid chromatography with mass spectrometric detection (GLC-MS), 19 individual C12--C24 FAs were identified, the main fraction of which were palmitic (~ 23%), stearic (~ 22%), linoleic (~ 14%) and α-linolenic (~ 33%) acids. The established atypical ratio of FAs (a simultaneous high content of both saturated FAs and polyunsaturated α-linolenic acid) is possibly due to the adaptation of cells to in vitro growth conditions. Phytochemical analysis of the secondary metabolites was carried out using ultra-performance liquid chromatography with electrospray ionization mass spectrometric detection (UPLC MS). Compounds belonging to different structural groups of isoflavones were found. Aglycones (calycosin, formononetin and afrormosin isomer), glucosides (formononetin glucoside), as well as esters of glucosides (malonylglycosides of calicosin, formononetin, afrormosin isomers, glycitein and genistein) were detected. These secondary metabolites are widespread in plants of the Fabaceae family; however, isoflavones are rare in representatives of the Alhagi genus. The presence of malonylated isoflavone glycosides in Alhagi spp. was shown for the first time. endemic plant species, Alhagi, in vitro cell culture, callus cell culture, isoflavones, fatty acids All studies were carried out using the equipment of the "Experimental Biotechnological Facility" and the "All-Russian Collection of Cell Cultures of Higher Plants" of IРР RAS. This work was supported by the Russian Foundation for Basic Research (RFBR), contract no.18-54-06021 (Az_a), and the Government of the Russian Federation, Megagrant Project no. 075-15-2019-1882.


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