Denitration of peroxynitrite-treated proteins by "protein nitratases" fromdog prostate

Putative "protein nitratases," which catalyze denitration of peroxynitrite (PN)-treated proteins, were detected in the crude extract of dog prostate. Nitratase activity was monitored by the decreased intensity of nitrotyrosin e immunoreactive-bands in Western blot and increased nitrate level in dialy sate of incubation mixture, which contained prostate crude extract, proteas e inhibitors and a PN-treated substrate, such as treated histone (III-S), B SA, invertase, or polylysine. Nitratases were activated by preincubation wi th m-calpain/Ca2+. Furthermore. after denitration, the activity of PN/DTT-t reated invertase decreased to the similar activity level of DTT-treated inv ertase. At feast two different types of nitratases may occur: type I, reduc tant-dependent, and type II, reductant-independent.