UC Davis

Carbohydrates are the most abundant biomolecule in nature and are involved mainly in the central metabolic processes of life and in providing structural integrity across the different domains of life. Carbohydrates also make up a major portion of our diets, with the low-molecular-weight and highly digestible carbohydrates serving as our main source of energy, while the high-molecular-weight and indigestible structures are carried to the distal gut where the gut microbes can utilize them. These gut microbes can in turn affect our physiology and health. Numerous studies have shown that dietary carbohydrates are implicated in some disease states, and that this can be mediated by the food-microbe-host interactions. It is therefore necessary that the analytical tools for carbohydrate characterization be able to speciate between the myriad structures of carbohydrates in food.

In this research work, a novel bottom-up LC-MS/MS-based glycomics method to characterize and quantify polysaccharides is presented. A non-enzymatic chemical reaction based on Fenton’s chemistry was used to depolymerize polysaccharides into smaller oligosaccharide structures. In Chapter 1, an overview of carbohydrate structures and a survey of various techniques for carbohydrates analysis is provided. In Chapter 2, the polysaccharide analysis workflow was optimized and used to identify polysaccharides in various types of food, while Chapter 3 demonstrated how the workflow was improved to provide accurate and reproducible quantitation of multiple polysaccharides. In Chapter 4, an integrated multi-glycomics protocol was outlined in the most detailed way. This protocol contained three different LC-MS/MS-based glycomics analyses, namely monosaccharide-, linkage-, and polysaccharide analyses. Several examples of applying these methods were also presented. Lastly, Chapter 5 provides the summary and the future implications of these analytical workflows in the field of carbohydrates research.