Conformational changes of serum albumin induced by ascorbic acid.

Bovine serum albumin (BSA) was found to inhibit the autooxidation of ascorbic acid (AA) at physiologic pH. The spontaneous oxidation rate of AA at 1 X 10(-5) M was 0.87 mumol X L-1 min-1. In the presence of 1 microM BSA, the rate is 15% of the spontaneous rate (0.13 mumol X L-1 X min-1). The u.v. difference spectrum of the AA:BSA complex reveals a decrease in absorbance at 204 nm. These data provide evidence that AA binds to BSA and induces a conformational change in the BSA molecule.