The effect of glycation on bovine serum albumin conformation and ligand binding properties with regard to gliclazide

摘要

AbstractAlbumin, the major serum protein, plays a variety of functions, including binding and transporting endogenous and exogenous ligands. Its molecular structure is sensitive to different environmental modifiers, among which glucose is one of the most significant.In vivoalbumin glycation occurs under physiological conditions, but it is increased in diabetes. Since bovine serum albumin (BSA) may serve as a model protein inin vitroexperiments, we aimed to investigate the impact of glucose-mediated BSA glycation on the binding capacity towards gliclazide, as well as the ability of this drug to prevent glycation of the BSA molecule. To reflect normo- and hyperglycemia, the conditions of the glycation process were established. Structural changes of albumin after interaction with gliclazide (0–14μM) were determined using fluorescence quenching and circular dichroism spectroscopy. Moreover, thermodynamic parameters as well as energy transfer parameters were determined. Calculated Stern-Volmer quenching constants, as well as binding constants for the BSA-gliclazide complex, were lower for the glycated form of albumin than for the unmodified protein. The largest, over 2-fold, decrease in values of binding parameters was observed for the sample with 30mM of glucose, reflecting the poorly controlled diabetic state, which indicates that the degree of glycation had a critical influence on binding with gliclazide. In contrast to significant changes in the tertiary structure of BSA upon binding with gliclazide, only slight changes in the secondary structure were observed, which was reflected by about a 3% decrease of the α-helix content of