[Non-enzymatic glycation of human serum albumin: influence on thebinding kinetics of the benzodiazepine binding sites].

Abstract

Human serum albumin was non-enzymatically glycated in vitro and the glycation rate determined using an affinity chromatography method. The influence of glycation on the binding of the model ligand, dansylsarcosine, at the benzodiazepine binding site was determined with a stopped-flow method. Fluorescence time curves were recorded during the binding process. As the glycation rate increased, the association velocity constant, k2, decreased from 533.3 s-1 (glycated albumin 0.048 of total serum albumin) to 218.1 s-1 (glycated albumin 0.158 of total serum albumin). The affinity constant, KA, showed a corresponding decrease from 7.61 x 10(5) l/mol (fraction of glycated albumin 0.048) to 2.60 x 10(5) l/mol (fraction of glycated albumin 0.158). The dissociation velocity constant, however, increased from 17.3 s-1 (fraction of glycated albumin 0.048) to 19.8 s-1 (fraction of glycated albumin 0.158). The inhibition of binding probably occurs via an allosteric mechanism.