Enzyme self-inactivation is a main limitation of the preparation of eicosanoids |
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Authors: | Stanislav I Shram Tatyana Yu Lazurkina Nikolay F Myasoyedov Sergey D Varfolomeyev |
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Institution: | (1) Department of Chemistry of Physiologically Active Agents, Institute of Molecular Genetics of RAS, Kurchatov Square, 123182 Moscow, Russia;(2) Chemical Enzymology Department, Faculty of Chemistry, The Lomonosov Moscow State University, 119899 Moscow, Russia |
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Abstract: | Synthesis of prostanoids is accompanied by various processes reducing the product yield. These processes are also known to
affect syntheses of thromboxane (TX) and 12(S)-hydroxy-5(Z),8(Z),10(E),14(Z)-eicosatetraenoic acid (12-HETE). Partially purified preparations of TX synthase and prostaglandin
(PG) synthase were used to optimize TX synthesis with respect to concentrations of the enzymes and eicosapolyenoic acid (EPA).
Conditions for the maximum product yield and the minimum consumption of enzymes were determined. Consumption of the TX synthase
was large owing to its inactivation during the reaction and the nonenzymatic destruction of the intermediate product PG-endoperoxide.
Separate addition of PG and TX synthases increased the product yield by preventing EPA sorption on ballast proteins. Microsomal
12-lipoxygenase (12-LO) was also shown to be inactivated during the reaction, and this process was the major limitation of
12-HETE synthesis. Lipoxygenase reaction in the presence of some reducing agents led to a considerable increase of the 12-HETE
yield, supposedly by preventing further oxidation of the 12-LO reaction product 12-hydroperoxy derivative of eicosatetraenoic
acid. The possibility of using human blood platelet microsomes for preparation of some derivatives of EPAs is discussed. |
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Keywords: | Eicosanoids thromboxane 12-HETE prostaglandin synthase thromboxane synthase 12-lipoxygenase biosynthesis enzyme self-inactivation |
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