Title: Functionalized C-Glycoside Ketohydrazones: Carbohydrate Derivatization that Retains the Ring Integrity of the Terminal Reducing Sugar Authors
Submitted to: Analytical Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 3, 2010
Publication Date: March 15, 2010
Citation: Price, N.P., Bowman, M.J., Legall, S., Berhow, M.A., Kendra, D.F., Lerouge, P. 2010. Functionalized C-glycoside ketohydrazones: Carbohydrate derivatization that retains the ring integrity of the terminal reducing sugar. Analytical Chemistry. 82(7):2893-2899. Interpretive Summary: New methods are required for the easy detection and analysis of sugars. Most current methods for analyzing sugars depend upon making various colored or fluorescent sugar derivatives. But, because of sugar ring opening this generally results in sugar derivatives that are markedly different to the starting parent sugar. In this paper we describe a new type of sugar derivatives called C-glycoside ketohydrazones, which can be made to be colored or tagged with fluorescence for easy detection of the sugars. The method can also be used to immobilize sugars onto surfaces, such as onto membranes or beads. The chemistry developed to do this is mild enough for a wide range of different sugars. The method will be of interest to the US sugar and biomaterials industries, and for testing of sugar-based materials for the biofuels industry.
Technical Abstract: Glycosylation often mediates important biological processes through the interaction of carbohydrates with complementary proteins. Most chemical tools for the functional analysis of glycans are highly dependent upon various linkage chemistries that involve the reducing-terminus of carbohydrates. However, because of ring opening, the structural integrity of the reducing sugar ring (pyranose or furanose) is lost during these techniques, resulting in derivatized carboydrates that markedly differ from the parent molecule. This paper describes a new aqueous-based, one-pot strategy that involves first converting the sugar to a C-glycoside ketone, followed by conversion to ketohydrazones or oximes. Hence the C-glycoside ketones are tagged with fluorescence, colored, cationic, or biotin labeled groups, or immobilized onto hydrazine-functionalized beads. No activating or protecting groups are required, and the chemistry is mild enough for a wide range of carbohydrates. We demonstrate the versatility of the approach to diverse glycans, including bead immobilization and lectin analysis of acarbose, an anti-diabetic drug, dabsyl-tagged enzyme substrates to screen cellulases, and for the analysis of plant cell wall hemicellulosics.