The analysis of complex carbohydrates by fourier transform-infrared microspectrometry and single-bounce attenuated total reflection spectrometry

Abstract

A strong need exists for the development of methodologies for compositional and structural analyses of complex carbohydrates. Vibrational spectrometry is a valuable and powerful tool for the interrogation of many chemical systems, both qualitatively and quantitatively and is applicable to the analyses of complex carbohydrates. Carbohydrates play numerous critical roles in biochemical systems, and they are ubiquitous components of living organisms. Biologically, their role as a source of energy for physiological processes is essential. More profoundly, however, they play crucial roles in the maintenance of cellular structural integrity and biosynthesis, and oligosaccharides are required for the direction of these processes and also behave as chemical messengers. Oligosaccharides are difficult and expensive to extract from biological sources, and, typically, only very small quantities are available for analysis. Therefore, a sensitive analytical method that can interrogate microgram quantities of sample is necessary. A methodology to determine the composition of N-linked mammalian oligosaccharides was developed with the use of Fourier transform infrared microspectrometry combined with chemometrics. This initial methodology was later modified for compositional and structural elucidations by single-bounce attenuated total reflection spectrometry. These results demonstrated predictions with less than four percent error in both validation and double blind studies. Various sources of (1-3)-b-D-glucans have been found to have tumor-necrotizing effects in mammals. Many of these anti-tumor glucans contain this structure as a backbone with O-6-linked b-glucosyl branches with a degree of branching of 1:3. A method of the structural analysis of intact polysaccharides was investigated by Fourier transform infrared spectrometry/attenuated total reflection spectrometry. The system was comprised of maltose and cellulose standards, as the sole monosaccharide subunit in these polysaccharides is D-glucose. The results indicate very high predictability of the relative extent of alpha and beta linkage.