Antioxidant reactivity toward nitroxide probes anchored into human serum albumin. A new model for studying antioxidant repairing capacity of protein radicals

A new strategy to evaluate accessibility of antioxidants to radical proteins has been developed using nitroxide prefluorescent probes anchored into human serum albumin (HSA). Binding association constants for the nitroxide probes C343T and QT with HSA were 5 × 104 and 9 × 104 M−1, respectively. Rate constants for the nitroxide reduction by antioxidants in HSA were determined finding kHSA/kbuffer ratio of 0.8, 1.9, and 0.075 for ascorbic acid, Trolox, and caffeic acid, respectively, for the nitroxide C343T reduction.

Graphical abstractKinetic rate constant values for the nitroxide reduction bound to Human serum albumin reveal influence of environment and accessibility factors on the antioxidant ability to repair protein free radicals.Figure optionsDownload full-size imageDownload as PowerPoint slide