Intensification of serum albumin amyloidogenesis by a glycation-peroxidation loop (GPL).

The interaction of reducing sugars with proteins leads to the formation of advanced glycation end products (AGE) and reactive oxidative species (ROS). ROS peroxidise free or membrane included unsaturated fatty acids, leading to generate reactive aldehydes as advanced lipid peroxidation end products (ALE). Aldehydes from lipid peroxidation (LPO) react with proteins to cause alteration of protein structure to exacerbate complication of diseases. Here we studied serum albumin glycation in the presence and absence of liposomes as a bio-membrane model to investigate protein structural changes using various techniques including intrinsic and extrinsic fluorescence spectroscopies and electron microscopy analysis. Accordingly, serum albumin glycation and fibrillation were accelerated and intensified in the presence of liposomes through a hypothesized glycation-peroxidation loop (GPL). Together, our results shed light on the necessity of reconsidering diabetic protein glycation to make it close to physiological conditions mimicry, more importantly, proteins structural change due to diabetic glycation is intensified in the proximity of cell membranes which probably potentiates programmed cell death distinct from apoptosis. Image 1 • Lipid peroxidation (LPO) of liposomes produces reactive carbonyl compounds that induce fibrillogenesis in serum albumin. • Glycation of serum albumin induces generation of reactive oxygen species (ROS). • The generated ROSs induce LPO in the presence of liposome that accelerates fibrillation of the glycated serum albumin. • The synergistic effect of protein glycation and LPO on fibrillogenesis was explained by a glycation peroxidation loop (GPL). [ABSTRACT FROM AUTHOR]