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Spectral intermediates of prostaglandin hydroperoxidase


, : Spectral intermediates of prostaglandin hydroperoxidase. European Journal of Biochemistry 144(2): 381-385

Microsomes from ram seminal vesicles or purified prostaglandin H synthase supplemented with either arachidonic acid or prostaglandin G2 formed an unstable spectral intermediate with maxima at 430 nm, 525 nm and 555 nm and minima at 410 nm, 490 nm and 630 nm. At -15 degrees C the band at 430 nm disappeared within 4 min whereas the trough at 410 nm increased three fold. At higher temperatures (10-37 degrees C) spectral complex formation and decay were observed in less than 1 s. An apparent KS-value of about 3 microM was determined for the titration of purified prostaglandin synthase with prostaglandin G2 at -20 degrees C. Substrates for cooxidation reactions of prostaglandin synthase such as phenol, hydroquinone and reduced glutathione as well as the peroxidase inhibitors cyanide and azide inhibited the prostaglandin G2-induced spectral complex formation. The oxene donor iodosobenzene and hydrogen peroxide formed a spectral intermediate analogous to the complex observed with prostaglandin G2 or arachidonic acid in ram seminal vesicle microsomes as well as with the purified prostaglandin synthase. These results are interpreted as the formation of a ferryl-oxo complex (FeO)3+ of the heme of prostaglandin synthase with prostaglandin G2 analogous to the formation of compound I of horseradish peroxidase.

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Accession: 044375294

PMID: 6436022

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Related references

Nastainczyk, W.; Schuhn, D.; Ullrich, V., 1984: Spectral intermediates of prostaglandin hydroperoxidase ec 1.14.99.1. Microsomes from ram seminal vesicles or purified prostaglandin H synthase supplemented with either arachidonic acid or prostaglandin G2 formed an unstable spectral intermediate with maxima at 430, 525 and 555 nm and minima at 410, 490 and 630 nm....

Nastainczyk W.; Ruf H.H.; Schuhn D., 1984: Spectral properties of the enzyme substrate complex of prostaglandin hydroperoxidase and prostaglandin g 2. Thaler-Dao, H , A Crastes De Paulet And R Paoletti (Ed ) Icosanoids And Cancer; Satellite Symposium Of The 2nd International Congress on Hormones And Cancer, Ile De Bendor, Sept 1983 Xix+289p Raven Press: New York, N Y , Usa Illus 255-258

Dietz, R.; Nastainczyk, W.; Ruf, H.H., 1988: Higher oxidation states of prostaglandin H synthase. Rapid electronic spectroscopy detected two spectral intermediates during the peroxidase reaction with prostaglandin G2. The reaction of prostaglandin H synthase with prostaglandin G2, the physiological substrate for the peroxidase reaction, was examined by rapid reaction techniques at 1 degree C. Two spectral intermediates were observed and assigned to higher oxida...

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