Nonenzymatic glucosylation of proteins: a new and rapid solution for in vitro investigation

The rates of nonenzymatic glucosylation of albumin, high density lipoprotein (HDL) and low density lipoprotein (LDL) were determined in vitro using 14C]glucose repurified by a new and rapid HPLC method. All commercial preparations were found to contain contaminants reacting 15-20-times faster with protein than the repurified 14C]glucose. Removal of contaminants was critical to the rate determinations and constitutes a substantial improvement over the widely used existing method. The initial rates of nonenzymatic glucosylation determined in vitro for albumin, HDL and LDL were used to predict normal in vivo levels of 0.40, 0.65 and 0.08 mol glucose per mol protein, respectively. This is within the range of values found in vivo for albumin and LDL, but low for HDL. These values would be expected to increase 2-4-fold in diabetes.