Oxidative Stress Induces the Formation of D ‐Aspartyl Residues in the Elastin Mimic Peptides

Racemization of aspartyl (Asp) residues in peptides and proteins has been considered to be a nonenzymatic chemical reaction which occurs via succinimide formation. However, it has not been known yet what conditions in living body accelerate the inversion of the L ‐ to the D ‐form. Here, we examined the effect of ultraviolet (UV) exposure or oxidative stress on the formation of D ‐Asp residues in the elastin mimic peptides with or without heat treatment. As a result, UV exposure did not affect the D ‐Asp formation in peptides. On the other hand, the amount of D ‐Asp in heat‐treated peptide solution at the same time as addition of HO . radical, H 2 O 2 , and lipid peroxide was significantly increased. These results indicate that the inversion rate to D ‐form of Asp residues in skin elastin is accelerated by generation of reactive oxygen species (ROS), and that oxidative stress might be closely related to D ‐Asp formation in aging proteins.