Investigation of thermal reversibility and stability of glycated human serum albumin

Protein glycation, the process by which carbohydrates attach to proteins upon covalent binding, can alter protein thermal reversibility and stability. Protein stability and reversibility have important role in protein behavior and function. Also they are benefit properties for drug produce and protein industrial applications. In this research the thermal reversibility and stability changes in human serum albumin (HSA) were studied upon incubation with glucose (GHSA) under physiological conditions for 21 and 35 days. The thermal reversibility and stability changes in GHSA were evaluated using circular dichroism (CD), UV–vis spectroscopy, fluorescence spectroscopy and differential scanning calorimetry (DSC). Our results showed that the glycation of HSA increased its thermal reversibility and stability, but decreased its conformational entropy compared to fresh native HSA and untreated HSA. Free lysine content assay (TNBSA test) indicated glucose can bind to protein covalently. These alterations were mainly attributed to the formation of crosslink between the lysine residues of HSA upon incubation with glucose.