Determination of the structural environment of the tyrosyl radical in prostaglandin H2 synthase-1: a high frequency ENDOR/EPR study.
The catalytically active tyrosyl radical which gives rise to the "wide doublet" (WD1) signal in ovine Prostaglandin H2 Synthase-1 has been studied using high frequency (HF) pulsed ENDOR and EPR. A hydrogen-bonded deuteron was directly detected in HFENDOR (130 GHz) spectra of 1H2O/2H2O-exchanged samples. The HFENDOR spectral simulations required a distribution in hydrogen bond distances to achieve proper fits. This range of distances was consistent with that used to model the distribution in gX values detected in pulsed HFEPR spectra. Possible hydrogen-bonding partners, as well as implications regarding the mechanism of self-inactivation for PGHS, are discussed.
Wilson
John C
JC
Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Wu
Gang
G
Tsai
Ah-lim
AL
Gerfen
Gary J
GJ
D000818:Animals; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D005609:Free Radicals / Q000737:chemistry; D007527:Isoenzymes; D011451:Prostaglandin-Endoperoxide Synthases / Q000737:chemistry* / Q000378:metabolism; D012756:Sheep; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry
D005609:Free Radicals; D007527:Isoenzymes; D014443:Tyrosine; D011451:Prostaglandin-Endoperoxide Synthases