Nonenzymatic galactosylation of human serum albumin. In vitro preparation.
Incubation of purified human serum albumin with D-[1-14C]galactose (5 mM) or D-[1-14C]glucose (5 mM) in vitro for 7 days under physiological conditions resulted in the time-dependent accumulation of radioactivity into trichloroacetic acid-precipitable material. Comparative studies indicated that the rate of sugar incorporation into albumin increased with increasing pH and temperature of incubation and followed a first order dependence with regard to monosaccharide and albumin concentrations. The extent of nonenzymatic galactosylation of human albumin was approximately 300% greater than the extent of nonenzymatic glucosylation under equivalent experimental conditions. Prolonged dialysis of the modified albumins against a large excess of the unlabeled monosaccharides failed to alter the amount of protein-bound radiolabeled carbohydrate, suggesting that the linkage between sugar and albumin is covalent in nature. The post-translational modification of proteins by nonenzymatic galactosylation may be of physiological significance in individuals with reduced galactokinase or galactose-1-phosphate uridyl transferase activities.
D002250:Carbon Radioisotopes; D005690:Galactose; D005947:Glucose; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D012710:Serum Albumin, Bovine / Q000378:metabolism*; D013696:Temperature
D002250:Carbon Radioisotopes; D012710:Serum Albumin, Bovine; D005947:Glucose; D005690:Galactose