Mass spectrometric investigation of synthetic glycoside of muramyl dipeptide immobilized on fumed silica surface

Secondary structure of muramyl dipeptide glycoside in pristine state and immobilized on nanosilica surface

“…Pyrolysis of carbohydrate fragment, aglycone and peptide fragment of MDP O-glycoside in the pristine state and adsorbed on the silica surface (Figure 2-4) have been determined by TPD-MS. Earlier we identified pyrolysis stages of MDP O-glycoside in the pristine state and adsorbed on silica surface [40]. Our study has revealed that binding of MDP O-glycoside to silica surface occurs by means of peptide fragment but detailed investigation of binding mechanism haven`t done yet.…”

“…Elimination of peptide fragment from one molecule triggers the removal of the aglycone from neighbor molecule (scheme 2). This causes the second order of reaction [40]. Both substituents have values of pre-exponential factor of the same order.…”

“…Both substituents have values of pre-exponential factor of the same order. Activation energies have close values approximately 132 kJ/mole [40]. The pyrolysis of carbohydrate fragment in the pristine state and on the silica surface takes place at ≈250 °C due to glycosidic linkage disruption and elimination of two water molecules from pyranose ring of MDP O-glycoside with formation of substance in molecular form with m/z 125 (Figure 3A).…”

“…О-{(4-tert-butylcyclohexyl)-2-acetamido-2,3-dideoxy-βd-glucopyranoside-3-yl}-D-lactoyl-L-alanyl-D-isoglutamine (MDP О-glycoside , the scheme 1) was kindly gifted by the Department of Biological and Organic chemistry of Taurida National V.I. Vernadsky University [40,41]. Sample of MDP Оglycoside with a concentration of 0.6 mmol/g of on the silica surface was obtained by impregnation.…”

Investigation of chemical transformations of thiophenylglycoside of muramyl dipeptide on the fumed silica surface using TPD-MS, FTIR spectroscopy and ES IT MS

“…For all the samples, the sample vials were filled approximately 1/16 full, which helped limit interparticle diffusion effects [ 24 - 28 ]. Limiting the sample volume along with the high vacuum should further limit readsorption and diffusion resistance as described elsewhere [ 24 - 33 ]. The volatile pyrolysis products was passed through a high-vacuum valve (5.4 mm in diameter, a length of 20 cm and a volume of 12 mL) into the ionization chamber of the mass spectrometer where they were ionized and fragmented by electron impact.…”