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Catalysts 2014, 4(2), 174-185; doi:10.3390/catal4020174
Communication

Kinetic Isotope Effect of Prostaglandin H Synthase Exhibits Inverted Temperature Dependence

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Received: 28 February 2014; in revised form: 24 April 2014 / Accepted: 23 May 2014 / Published: 11 June 2014
(This article belongs to the Special Issue Enzymes in Organic Synthesis)
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Abstract: Conversion of arachidonic acid to prostaglandin G2/H2 catalyzed by prostaglandin H synthase (PGHS) is proposed to involve initial transfer of the C13 pro-(S) hydrogen atom from arachidonate to the Tyr385 radical in PGHS, followed by insertion of two oxygen molecules and several chemical bond rearrangements. The initial hydrogen-transfer was recently concluded to be a rate-limiting step in cyclooxygenase catalysis based on the observed intrinsic deuterium kinetic isotope effect values (Dkcat). In the present study, we have found that Dkcat values of both PGHS-1 and -2 show an unusual increase with temperatures in the range of 288–310 K, exhibiting an inverted temperature dependence. The value of lnDkcat, however, decreased linearly with 1/T, consistent with a typical Arrhenius relationship.
Keywords: prostaglandin H synthase-1 and -2; deuterium kinetic isotope effect; temperature dependence of KIE prostaglandin H synthase-1 and -2; deuterium kinetic isotope effect; temperature dependence of KIE
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Wu, G.; Kulmacz, R.J.; Tsai, A.-L. Kinetic Isotope Effect of Prostaglandin H Synthase Exhibits Inverted Temperature Dependence. Catalysts 2014, 4, 174-185.

AMA Style

Wu G, Kulmacz RJ, Tsai A-L. Kinetic Isotope Effect of Prostaglandin H Synthase Exhibits Inverted Temperature Dependence. Catalysts. 2014; 4(2):174-185.

Chicago/Turabian Style

Wu, Gang; Kulmacz, Richard J.; Tsai, Ah-Lim. 2014. "Kinetic Isotope Effect of Prostaglandin H Synthase Exhibits Inverted Temperature Dependence." Catalysts 4, no. 2: 174-185.


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