Thermal Fourier Transform Infrared Technique Quickly Detects an Early Onset of Glycation-Induced Conformational Changes of Human Serum Albumin

Abstract

Numerous potential inhibitors for prevention of advanced glycation end products (AGEs) formation have been extensively investigated for their in vitro and in vivo features, but it would spend a lot of time studying. In the present study, a unique thermal Fourier Transform Infrared (FTIR) combined system as an accelerated method was attempted to simultaneously determine the thermal-dependent conformational changes of human serum albumin (HSA) in the HSA-ribose mixture and examine the onset of the structural transformation from α-helix to β-sheet structures with or without AGEs inhibitors used. The present results clearly indicate that native HSA had an onset temperature at 96°C for the irreversible thermal-induced structural transition from α-helices to β-sheets, whereas HSA-ribose mixture exhibited its onset temperature near at 78°C due to the early occurrence of glycation. However, the onset temperature of the α-helix to β-sheet transition was gradually changed from 78°C to 96°C by increasing the amount of sodium diclofenac or inositol, which was closed to that of the onset temperature of native HSA. This implies that the thermal-induced transition from α-helix to β-sheet for HSA in the HSA-ribose mixture was effectively prevented after adding sodium or inositol. The present study also suggests that this thermal FTIR technique not only rapidly accelerates the conformational changes of HSA-ribose mixture but also directly detects onset temperature of the α-helix to β-sheet transition in real time. This unique thermal FTIR combined system could be a useful tool to screen and evaluate quickly the glycation-induced conformational changes of proteins in a one-step process.