The role of oxidized myofibrillar protein aggregation and modification in advanced glycation end products formation

Protein oxidation is an important contributor to advanced glycation end products (AGEs) formation, although the underlying mechanisms remain unclear. We investigated how hydroxyl radical-induced oxidation of myofibrillar proteins (MPs) contributes to AGEs generation through aggregation and modification. Systems with different degrees of protein oxidation (mild, moderate, and severe) were established, revealing that N^ε-carboxymethyllysine levels (627.62-795.98 ng/g) increased progressively with increasing oxidation intensity, whereas N^ε-carboxyethyllysine levels peaked under moderate oxidation (1443.98 ng/g) but decreased under severe oxidation (1253.47 ng/g). These results demonstrated that the structure of MPs was partially unfolded (decreased α-helix content) during mild-to-moderate oxidation, facilitating the Maillard reaction between carbonylation modification and free amino groups to produce AGEs. Conversely, severe oxidation promoted protein reaggregation (increased β-sheet content and particle size), which sterically hindered modification site accessibility to reduce AGEs formation. These findings identified protein oxidation as a crucial regulator in AGEs generation, linking macrostructural transformations with molecular mechanisms.