Experimental and theoretical insight into resistance to glycation of bovine serum albumin

Serum albumin is the most abundant protein in plasma and is highly sensitive to glycation, leading to functional and structural alterations. These changes are subsequently involved in the pathophysiological events in diabetes. In this study, our aim is to investigate the formation of glycation products, structural alterations as well as to gain insight into the resistance to glycation using various inhibitors. Bovine serum albumin (BSA) was incubated with a constant glucose concentration (0.05M) for 10 weeks at 37 degrees C. Early, intermediary and advanced glycation end-products (AGEs) were estimated and the glycation induced structural changes were analysed. Complementary shape-based docking studies were carried out to supplement the experimental findings. Significant amounts of ketoamines, protein bound carbonyl content and AGE (pentosidine) were detected in in vitro glycation reactions of BSA. Glycation inhibition studies showed no appreciable change in ketoamine formation. However, significant inhibition in the formation of protein bound carbonyl content and pentosidine in the presence of aminoguanidine and Metformin were observed. Fluorescence study exhibited quenching of tryptophan-based emission and UV absorption of glycated BSA (G-BSA) compared to native BSA (N-BSA). Appreciable changes in secondary structures (alpha-helix, beta-sheet, beta-turn and random coils) were observed in G-BSA with aminoguanidine and Metformin. It was also noticed that the effect of Metformin and aminoguanidine drugs was reduced upon BSA with amino acid(s) modification. On the other hand, native BSA exhibited higher binding affinities and stronger binding interactions with both drugs. Aminoguanidine and Metformin exhibited substantial resistance to the formation of intermediary and AGE (pentosidine) molecules, as well as against secondary structural alterations. Hence these agents may protect the integrity and functionality of serum proteins and possibly contribute to reduction of pathophysiological complications in diabetes. (C) 2020 Elsevier B.V. All rights reserved.