| Autor: |
Gang Wu, Richard J. Kulmacz, Ah-Lim Tsai |
| Jazyk: |
angličtina |
| Rok vydání: |
2014 |
| Předmět: |
|
| Zdroj: |
Catalysts, Vol 4, Iss 2, Pp 174-185 (2014) |
| Druh dokumentu: |
article |
| ISSN: |
2073-4344 |
| DOI: |
10.3390/catal4020174 |
| Popis: |
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. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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