Rapid kinetics of tyrosyl radical formation and heme redox state changes in prostaglandin H synthase-1 and -2.

@article{Tsai1999RapidKO,
  title={Rapid kinetics of tyrosyl radical formation and heme redox state changes in prostaglandin H synthase-1 and -2.},
  author={Ah-lim Tsai and Guikai Wu and Graham Palmer and Bijan Bambai and J{\"o}rg K{\"o}hn and P. J. Marshall and Richard J. Kulmacz},
  journal={The Journal of biological chemistry},
  year={1999},
  volume={274 31},
  pages={21695-700}
}
Hydroperoxide-induced tyrosyl radicals are putative intermediates in cyclooxygenase catalysis by prostaglandin H synthase (PGHS)-1 and -2. Rapid-freeze EPR and stopped-flow were used to characterize tyrosyl radical kinetics in PGHS-1 and -2 reacted with ethyl hydrogen peroxide. In PGHS-1, a wide doublet tyrosyl radical (34-35 G) was formed by 4 ms, followed by transition to a wide singlet (33-34 G); changes in total radical intensity paralleled those of Intermediate II absorbance during both… CONTINUE READING