ALBUMIN CHEMICAL MODIFICATION INDUCED BY OXYGEN RADICALS

Tryptophan and tyrosine modifications and proteolytic susceptibility h ave been studied after exposure of human serum albumin to oxygen radic als. Tryptophan was rapidly lost with (OH)-O-. exposure, and significa nt production of bityrosine occurred. The modified protein exhibited a substantial increase in proteolytic susceptibility. The combination o f (OH)-O-. + O-2(-) (and O-2) which may mimic biological exposure to o xygen radicals, induced tryptophan loss and bityrosine production. The pattern of such changes was similar to that seen with (OH)-O-. alone, although the extent was less severe. Oxidative modification may provi de denatured substrates for intracellular proteolysis.