Abstract
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.
Highlights
[~-‘~C]galactos(e5 mM) or ~ - [ l - ’ ~ C ] g l u ~ o s(5e m ~ in) galactosylation of human serum albumin in vitro, and in vitro for 7 days under physiological conditionsresulted addition, we demonstrate that human albumin incorporates in the time-dependent accumulation of radioactivity galactose both fasterand more extensively than glucose under intotrichloroaceticacid-precipitablematerial.Comvarious experimental conditions
Humanserum albumin was purified from fresh human serum by affinity chromatography on AB-Gel blue (Bio-Rad) [31], followed by gel filtration on Bio-Gel P150 (Bio-Rad) prior to recrystallization [32]
D-Galactose and D-glulonged dialysis ofthe modified albuminsagainst a large cose were purchased from Sigma.~-[l-’~C]Galactos(6e.2 mCi/mmol) excess of the unlabeled monosaccharides failedto alter was obtained from New England Nuclear, ~-[l-~~C]Gluco(5s.e8mCi/
Summary
Follow this and additional works at: https://digitalcommons.uri.edu/cels_past_depts_facpubs. This article is available at DigitalCommons@URI: https://digitalcommons.uri.edu/cels_past_depts_facpubs/47. No 1, Issue of January 10.pp. 111-115.1982 Printed in U.S.A
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