Partially Folded Glycated State of Human Serum Albumin Tends to Aggregate

The interaction of reducing carbohydrates with proteins leads to a cascade of reactions that are known as glycation or Maillard reactions that results in the formation of advanced glycation end products. We studied the impact of incubation with various sugars for 4 weeks on the behaviour of human serum albumin incubation using CD, fluorescence, UV–Vis spectrophotometry and polyacrylamide gel electrophoresis. Three weeks of incubation of human serum albumin with sugars resulted in the formation of an intermediate state with negative CD peaks at 222 and 208 nm characteristic of α-helix. The form also retained tertiary contacts but with altered tryptophan environment and high ANS binding indicative of molten globule state. Further incubation of human serum albumin for 4 weeks resulted in the formation of an intermediate form with negative CD peak at 217 nm, characteristic of β-sheet, decreased ANS fluorescence and increased thioflavin T fluorescence characteristic of an aggregated state. Prolonged exposure of human serum albumin to reducing sugars thus exerts greater deleterious effects on its structure and formation of aggregates.