Human Placental Cytochrome P-450: Microsomal Preparation and Purification
The human placenta contains several microsomal oxidases important in the oxidation of steroids and drugs (Pelkonen and Pasanen, 1984; Pelkonen, 1980; Namkung et al., 1983). An important function of placental cytochrome P-450 is the aromatization of steroids (Meigs and Ryan, 1968). This aromatase activity is induced by the cAMP analog, dibutyryl cAMP, and theophylline indicating a possible control by kinase (Bellino and Hussa, 1978). Further study of the regulation of this and other cytochrome P-450 activities requires the purification of the terminal oxidase, cytochrome P-450, and the associated cytochrome c reductase. Methods of purifying cytochrome P-450 (Pasanen and Pelkonen, 1981; Pelkonen and Pasanen, 1982) and cytochrome c reductase (Bellino, 1982; Yasukochi and Masters, 1976) from human placenta have been reported. However, due to the low specific content of cytochrome P-450 (0.05–0.15 nmol/mg) in human placental microsomes only small amounts of cytochrome P-450 or the reductase can be obtained from a single placenta.
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