Differential modulation of human lysozyme aggregation by sugar and derivatives: a biophysical insight

Human Lysozyme, an essential enzyme within the innate immune system, is particularly vulnerable to glycation, resulting in structural modifications and aggregation. This study was conducted to examine the effects of Glucose, Fructose, Xylose, and Methylglyoxal on the glycation of human lysozyme and the subsequent aggregation that occurs. To evaluate conformational changes, CD spectroscopy was utilized, while glycation levels were quantified using AGE-specific fluorescence, NBT assay, and Levine methods. The evaluation of hydrophobicity changes was performed through ANS dye binding, and the propensity for aggregation was assessed using the ThT binding assay. Additionally, further characterization was conducted using SDS-PAGE, Transmission electron microscopy (TEM), and confocal microscopy. The results indicated that glycation with all tested sugars and derivative led to conformational changes in lysozyme, accompanied by increased hydrophobicity and an enhanced tendency for aggregation. Notably, methylglyoxal and xylose demonstrated a greater likelihood of forming advanced glycation end products. The aggregation of glycated lysozyme was corroborated through SDS-PAGE, TEM, and confocal microscopy analyses. Furthermore, it was observed that glycation adversely affected the lytic activity of lysozyme. These findings underscore the negative impact of glycation on the structure, function, and aggregation of lysozyme. A comprehensive understanding of the mechanisms driving glycation-induced aggregation may facilitate the advancement of therapeutic strategies aimed at addressing diseases associated with lysozyme dysfunction and glycation.