Glycosides molecular weight determination

This example shows well the use of both LC/MS ionisation techniques for targeting unknowns. LC/TSP-MS indicated that compounds 8 and 10-13 had common sub-units (identical fragments (MW 358)), while CF-FAB allow the on-line molecular weight determination of all of these types of oligomers. The combination of both types of information has thus allowed the early recognition of this type of large secoiridoid glycosides. 

A possibility of using the viscosimetiy and sedimentation and diffusion methods in studying the process of enzyme chitosan hydrolysis is discussed in the chapter. It is shown that a change in the intrinsic viscosity of chitosan may be determined by both the hydrolysis process in the glycoside bonds and transformation of the supramolecule stmcture of the polymer. Thus, for setting the hydrolysis process it is necessary to use an absolute method for molecular weight determination. 

FAB mass spectra of alkali metal-cationized unsaturated C-glycosides such as 16 are useful for molecular weight determinations of these compounds. ... 

The response (a decrease of viscosity) is a direct consequence of the action of the enzyme on its substrate, since the splitting of the glycosidic bonds gives a decrease in the viscosimetric average molecular weight and hydrodynamic volume of the hyaluronan chains and hence a decrease in the intrinsic and relative viscosities. With this method the rate at different concentrations cannot be compared because the initial viscosities are different and rheological measurements do not coincide. To eliminate these problems, a kinetic dilution methodology for the viscosimetric study of the substrate concentration dependence of the action of hyaluronidase was proposed [135,136]. We were able to determine the rate of reaction, expressed as the number of moles of bonds broken per unit of time, from viscosimetric data [136]. 

Tokura et al.49 synthesized a polyamide of the Perlon type (40) starting from a 6-O-carboxymethyl-D-glucosamine derivative as monomer.This compound was obtained by carboxylmethylation of chitin with monochloroacetic acid, followed by hydrolysis of the glycosidic linkage. Hie molecular weight (Mw 15,000) of the resulting water-soluble polyamide 40 was determined by gel-permeation chromatography and electrophoresis (Scheme 11). 

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