Membrane bound cyptochrome P-450 determines the optimal temperatures of NADPH-cytochrome P-450 reductase and ctyochrome P-450-linked mono-oxygenase reactions in rat and trout hepatic microsomes.
Prema Gurumurthy; Gilbert Mannering J.
Biochemical and Biophysical Research Communications; 1985; 127; 571-577.
The hepatic mono-oxygenase systems largely responsible for the biotransformation of drugs and other xenobiotics are comprised of NADPH-cytochrome P-450 reductase and multiple forms of cytochrome P-450. Optimal temperature for these systems in the trout and rat are 26° and 37°, respectively. Purified trout and rat reductases are optimally functional at 26° and 37°, respectively, when added to trout and rat microsomes. However, rat reductase was shown to function optimally at 26° when added to trout microsomes and trout reductase functioned optimally at 37° when added to rat microsomes. Corresponding shifts in optimal temperatures of ctyochrome P-450-linked O-deethylation of 7-ethoxycoumarin occurred when these reductases were added to rat or trout microsomes. It is proposed that the phospholipid annulus surrounding the active site of membrane-bound cytochrome P-450 determines the optimal temperature of cytochrome P-450 systems.
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