Oxidative damage to proteins is associated with oxidative stress, aging, and various age-related disorders. The level of oxidatively damaged protein is often measured by the presence of carbonyl groups in amino acid side chains. The degree of oxidative modification also can be measured by the change in protein conformation that accompanies changes in protein surface hydrophobicity. Two fluorescent chemicals, fluorescein thiosemicarbazide (FTSC) and 8-anilino-naphthalene-sulfonic acid (ANSA), have been known to bind nonspecifically to hydrophobic pockets of proteins. These chemicals were employed to measure a change in hydrophobicity in hydrogen peroxide-treated proteins. The development of this methodology would extend the way to observe modification of oxidatively damaged proteins. Present work is being carried out to determine binding specificity of the two chemicals to various modified proteins after native gel electrophoresis. - oxidative stress, aging, hydrophobicity, ANSA, FTSC