Thiazolidine peracetates: carbohydrate derivatives that readily assign cis-, trans-2,3- monosaccharides by gas chromatography - mass spectrometry analysis

Authors: Price, Neil; Hartman, Trina; Vermillion, Karl

Submitted to: Analytical Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/8/2018
Publication Date: 7/3/2018
Citation: Price, N.P.J., Hartman, T.M., Vermillion, K.E. 2018. Thiazolidine peracetates: carbohydrate derivatives that readily assign cis-, trans-2,3- monosaccharides by gas chromatography - mass spectrometry analysis. Analytical Chemistry. 90(13):8044-8050. doi:10.1021/acs.analchem.8b00976.
DOI: https://doi.org/10.1021/acs.analchem.8b00976

Interpretive Summary: Carbohydrates are the most abundant biomolecule on earth and they include simple sugars (e.g., glucose, mannose, and galactose), oligosaccharides consisting of short chains of sugar monomers, or complex branched sugar chains that may be composed of numerous types of sugars. Current methods to analyze the composition and structure of these carbohydrates have limitations. They often require multiple steps and usually have to be performed in combination with other analyses in order to fully characterize the material. In this present work, we describe a new technique for carbohydrate analysis that is much easier to perform and provides more detailed information about the carbohydrate structure. This method first involves a simple method to convert the sugars to a class of compounds called thiazolidine peracetates and then analyzing them by gas chromatography-mass spectrometry. In addition, we show that this technique can be combined with methods that label specific carbon molecules in the sugars with unique tags to obtain even more information about the composition and structure. This method can even be performed in bacterial cells to better understand the biosynthetic process of carbohydrates. This work is expected to be valuable to numerous areas of science, where carbohydrate analysis is required.

Technical Abstract: A novel group of carbohydrate derivatives is described that uniquely assign cis/trans-2,3 aldose stereoisomers at low nanomolar concentrations. Aldopentoses or aldohexoses, or component aldoses from hydrolysis of polysaccharides or oligosaccharides, react with cysteamine in pyridine to give quantitative formation of thiazolidines, which are subsequently peracetylated in a one-pot reaction. The non-polar thiazolidines peracetate (TPA) derivatives are analyzed by GC/EI-MS, each aldose giving rise to two TPA geometric isomers. The quantitative ratio of these enantiomers is dependent upon whether the parent monosaccharide is cis-2,3- (Rib, Lyx, Man, All, Gul, and Tal), or trans-2,3-aldose (Xyl, Ara, Glc, Gal, Ido, and Alt). TPAs generate observed EI-MS fragments ions characteristic of C1 – C2 and C3 – C4 bond cleavage of the parent sugars. This has been used to estimate the extent of metabolic labelling of microbial cell-wall carbohydrates, especially into the defining anomeric carbons and during aldolase/ketolase-catalyzed rearrangements.