Perhaps the major unsolved problem in diabetes is the pathogenesis of the long-term complications. There is ample evidence that in diabetes a variety of proteins are modified by non-enzymatic glucosylation, in direct proportion to the degree of hyperglycemia. Glucosylated hemoglobin, by far the most thoroughly studied protein, has proven useful as an aid in monitoring the control of diabetic patients. We plan to investigate the structure and function of other modified proteins with emphasis on those that may contribute to diabetic complications. We plan to utilize a combination of borohybride reduction, boronate affinity chromatography, and high performance liquid chromatography to accurately quantify glucosylated amino acids. Thus far, estimates of glucosylated hemoglobin and albumin have been seriously hampered by lack of accurate quantitation. We hope to develop an analytical scheme that detects chemical adducts rather than one that depends on incorporation of tritium label. This approach will be combined with mass spectroscopy in order to identify further products of the Maillard reaction scheme including possible sites of protein-protein cross-linking. Special emphasis will be placed on the following proteins: serum albumin, lens crystallins, and glomerular basement membrane collagen. We plan to establish the relationship between non-enzymatic glucosylation and life span of these proteins. In addition, we hope to gain insight into how glucosylation at specific sites on these proteins might affect function and fate in diabetic tissues.
