Tsaplina L A, Vrzheshch P V
Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119992, Russia.
Biochemistry (Mosc). 2007 Jun;72(6):631-9. doi: 10.1134/s0006297907060053.
Prostaglandin-H-synthase (PGHS) is a bifunctional enzyme catalyzing cyclooxygenase and peroxidase reactions and undergoing irreversible inactivation during catalysis. A new method for kinetic studies of both PGHS activities in the course of cyclooxygenase as well as peroxidase reactions and also preincubation with hydroperoxides is suggested. It is shown that peroxidase activity is retained after complete cyclooxygenase inactivation and cyclooxygenase activity is retained after complete peroxidase inactivation. Two-stage cyclooxygenase inactivation occurs on preincubation of PGHS with hydrogen peroxide. Studies on inactivation under various conditions indicate that chemical mechanisms of cyclooxygenase and peroxidase inactivation are different. The data allow development of kinetic models.
前列腺素-H-合酶（PGHS）是一种双功能酶，催化环氧化酶和过氧化物酶反应，并在催化过程中发生不可逆失活。本文提出了一种新方法，用于在环氧化酶反应以及过氧化物酶反应过程中对PGHS的两种活性进行动力学研究，同时也用于研究与氢过氧化物的预孵育。结果表明，在环氧化酶完全失活后，过氧化物酶活性得以保留；在过氧化物酶完全失活后，环氧化酶活性得以保留。PGHS与过氧化氢预孵育时会发生两阶段的环氧化酶失活。在各种条件下对失活的研究表明，环氧化酶和过氧化物酶失活的化学机制不同。这些数据有助于建立动力学模型。
