Alternative Molecules for Imaging Carbohydrates

Undergraduate: Max Lowman

Faculty Advisor: Carol Arnosti
Department: Chemistry

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Polysaccharides are major constituents of marine organic matter, fueling considerable heterotrophic production. Investigating the dynamics of carbohydrates in marine systems is difficult, however, because carbohydrates lack chemical characteristics that would allow them to be readily quantified or extracted. New advances in imaging techniques offer the opportunity to design novel probes which can be used to investigate the bioavailability of carbohydrates to microbial communities. We focused on the synthesis and characterization of alternative molecules for use in measuring the carbohydrate processing in marine systems. Our objectives were to label the disaccharide sucrose with an established fluorophore which fluoresces in the 530nm range and to test the efficacy of a new fluorophore that fluoresces in the 615nm range. Using a carbodiimide coupling reaction, the activated sucrose was reacted with the primary amine on the fluorescent tag to form a stable covalent linkage and NMR was used to characterize the reaction products. Texas Red cadaverine was chosen because it has minimal functional groups that could facilitate unwanted side reactions. Similarly to fluoresceinamine, its primary amine was used to form a stable covalent linkage to chondroitin-6-sulfate. This fluorphore's utility was also tested with laminarin. Unreacted tag was separated from the labeled polysaccharide and a stability test was carried out to measure shelf life of the labeled product.