Glycation Induced Generation of Amyloid Fibril Structures by Glucose Metabolites

The non-enzymatic reaction (glycation) of reducing sugars with proteins has received increased interest in dietary and therapeutic research lately. In the present work, the impact of glycation on structural alterations of camel serum albumin (CSA) by different glucose metabolites was studied. Glycation of CSA was evaluated by specific fluorescence of advanced glycation end-products (AGEs) and determination of available amino groups. Further, conformational changes in CSA during glycation were also studied using 8-analino 1-nephthlene sulfonic acid (ANS) binding assay, circular dichroism (CD) and thermal analysis. Intrinsic fluorescence measurement of CSA showed a 22 nm red shift after methylglyoxal treatment, suggesting glycation induced denaturation of CSA. Rayleigh scattering analysis showed glycation induced turbidity and aggregation in CSA. Furthermore, ANS binding to native and glycated-CSA reflected perturbation in the environment of hydrophobic residues. However, CD spectra did not reveal any significant modifications in the secondary structure of the glycated-CSA. Thioflavin T (ThT) fluorescence of CSA increased after glycation, illustrated cross β-structure and amyloid formation. Transmission electron microscopy (TEM) analysis further reaffirms the formation of aggregate and amyloid. In summary, glucose metabolites induced conformational changes in CSA and produced aggregate and amyloid structures.