Protein and Amino Acid Oxidation Is Associated with Increased Chemiluminescence

Incubation of 4% bovine serum albumin (BSA) with 1 mM tert-butyl hydroperoxide (t-BOOH) resulted in a peak of chemiluminescence followed by decay to a steady-state level of 18 counts per second above control. When using BSA of differing fatty acid content, the intensity of the initial peak was proportional to fatty acid content, while the steady-state chemiluminescence was independent of lipid content and depended only on BSA concentration. Light emission was inhibited by superoxide dismutase, desferrioxamine, and the antioxidant U-78518F. Oxidation of BSA by neutrophils activated with phorbol myristate acetate also increased chemiluminescence, in a process inhibitable by superoxide dismutase and U-78518F. When adding 1 mM t-BOOH in the presence of20 μM heme to tryptophan, tyrosine, or to a lesser extent histidine, chemiluminescence correlated with increased oxygen consumption and the appearance of carbonyl derivatives, suggesting that chemiluminescence is a result of the decay to ground level of excited carbonyls. Lysine and glycine, on the other hand, were not oxidized to carbonyls after exposure to t-BOOH and did not emit light or consume significant oxygen during this challenge.