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abstracts
Carbohydrates make up a significant component of the human diet. One approach to controlling blood glucose and serum insulin levels in individuals with type II diabetes is inhibition of intestinal α-glucosidases and pancreatic α-amylases. Two intestinal α-glucosidases, sucrase isomaltase (SI) and maltase glucoamylase (MGAM), are responsible for the final step of starch hydrolysis in mammals in the small intestine: the release of free glucose. Each enzyme consists of two catalytic subunits: N-terminal sucrase isomaltase (ntSI) and C-terminal sucrase isomaltose (ctSI); and N-terminal maltase glucoamylase (ntMGAM) and C-terminal maltase glucoamylase (ctMGAM). Here, residues hypothesized to impact substrate specificity of ctSI and ctMGAM will be presented, enhancing our understanding of the functionality of these enzymatic subunits as well as their overlapping substrate specificity.
abstracts
The way to a person's heart is through their stomach - not just their heart. All aspects of health are affected by sources of nutrition; not just health but social and political issues, too. The metabolism of starch into glucose is linked directly to the development of the human brain. There is considerable interest worldwide into the processing of starch and other foods by the intestinal microbiome. This talk will focus on the main mammalian intestinal enzymes that process starch, their structures, functions and potential roles in human health and disease. The alpha-glucosidases maltase-glucoamylase (MGAM) and sucrase-isomaltast (SI) are resident in the small-intestinal lumen and are responsible for generating glucose from a wide variety of starch structures. Their malfunction is responsible for many nutritional intolerances and diseases including diabetes, gastrointestinal cancers and obesity. A pediatric nutritional disorder directly associated with mutations in SI, Congenital Sucrase-Isomaltase Deficiency (CSID) has significant occurrence, especially in northern and indigenous populations. The structural analyses presented in this talk will shed light on the molecular basis for this disease, as well as the development of inhibitor analyses that are designed to investigate the roles of human intestinal glucosidases in health and disease.
abstracts
Nutritional research is continually demonstrating the strong interaction between the human colon microbiota and a healthy digestive system 1. It has been shown that this intestinal microbial population can influence our state of health including our metabolism, nutrient production and absorption, and the development of our immune system2. These symbiotic organisms have an important role in the metabolism of human dietary carbohydrates and exist by utilizing these sugars, which are not readily digested by upstream human enzymatic mechanisms. The ability of these microbes to utilize these sugars can also impact digestive disease states that include obesity, irritable bowel disorder, colonic cancer and Type 2 diabetes3. A dominant member of this environment is the bacterium Bacteroides thetaiotaomicron and has been characterized at efficiently utilizing carbohydrates in the colon. This symbiont has been shown to have a large repertoire of proteins and enzymes that have been predicted to be strongly involved in the capture and degradation of dietary sugars. In this study we focused on assessing the impact of a specific SusD-like protein on the utilization of dietary sugars. Biochemical evidence, as well as preliminary structural data provides support that this carbohydrate binding protein is capable of binding various dietary sugars. These interactions enable this bacterium to capture sugars derived from the colon and provide an available substrate for membrane bound glycoside hydrolases. The information gathered in this study can shed light on a part of digestion that is unclear at this point in time and create a connection between diet composition and its affect on a dominant member of the gut microbiota.
