Glucosylated albumin and its influence on salicylate binding.

Human serum albumin was incubated at 37 degrees in 0.01 M phosphate buffer (pH 7.4) under sterile conditions for up to 10 days with labeled [14C]glucose (1-25 mg/ml). Glucose incorporated into albumin was calculated following extensive dialysis of the incubation mixture. The results indicated that glucose reacted with albumin by a nonenzymatic process involving Schiff base formation and Amadori rearrangement to a stable ketoamine derivative. The degree of glucosylation was dependent on the reaction time, glucose concentration, and pH. Glucosylation was enhanced when albumin was fatty acid free. Glucosylated albumin was separated from unmodified albumin by cation exchange chromatography on carboxymethylcellulose and quantitated colorimetrically with 2-thiobarbituric acid. Salicylate binding studies revealed that the glucosylated component had a decreased salicylate binding capacity accompanied by a reduction in the number of classes of binding sites.