The chapter presents a study on cytochrome P-450 arachidonate oxygenase. Cytochrome P-450, the oxygen-activating component of the microsomal electron transport system, is an efficient catalyst for the oxygenated metabolism of arachidonic acid (AA). The chapter mentions that the reaction has an absolute requirement for NADPH and states the procedure of their stoichiometric relationship. The chapter describes methodology utilized in laboratory for the biochemical characterization of the hepatic microsomal AA cytochrome P-450 oxidase as well as its reconstitution utilizing solubilized and purified components of the microsomal electron transport system. In addition to the biochemical advantages of working with a defined system, reconstituted systems are excellent tools for the study of the regioselectivity of AA oxidation by different cytochrome P-450 enzymes. The chapter includes experiment that illustrates the reconstitution of AA oxygenase, utilizing either the major phenobarbital-inducible form of rat liver microsomal cytochrome P-450 or, alternatively, the major ciprofibrate- inducible form. It is shown by the radiochromatograms that the phenobarbital-inducible enzyme is an active epoxygenase, generating four regioisomeric EETs in an enantioselective manner. On the other hand, the ciprofibrate-inducible form catalyzes, almost exclusively, the ω-oxidation of the fatty acid to form 20-hydroxyeicosatetraenoic acid.
ASJC Scopus subject areas
- Molecular Biology