Some aspects of activation and inhibition of rat brain lipoxygenase.
1. Regulatory properties of lipoxygenase activity in rat brain cytosol were studied using linoleic acid (LA) as a substrate. 2. A change in the absorbance at 234 nm was biphasic when a mixture of LA and pre-formed hydroperoxide (LA-OOH) was incubated with freshly isolated native brain cytosol. Initially, a rapid depletion of LA-OOH was observed with a concomitant formation of LA-oxo compounds. This phase was followed by LA dioxygenation. 3. Both hydroperoxidase and dioxygenase activities of lipoxygenase were inhibited by micromolar concentrations of classic lipoxygenase inhibitors (phenidone, 5,8,11-eicosatriynoic acid and nordihydroguaiaretic acid). 4. The dioxygenase activity in dialysed cytsool was stimulated by nanomolar concentrations of H2O2 and micromolar concentrations of LA-OOH and it was inhibited by serotonin, dopamine and norepinephrine (IC50 25-43 microM).
Byczkowski
J Z
JZ
Toxicology Program, College of Public Health, University of South Florida, Tampa 33612.
Ramgoolie
P J
PJ
Kulkarni
A P
AP
D000818:Animals; D001921:Brain / Q000201:enzymology*; D004298:Dopamine / Q000378:metabolism; D004789:Enzyme Activation; D005260:Female; D006861:Hydrogen Peroxide / Q000378:metabolism; D007700:Kinetics; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000378:metabolism*; D015227:Lipid Peroxidation; D008084:Lipoxygenase / Q000378:metabolism*; D016859:Lipoxygenase Inhibitors / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism; D010084:Oxidation-Reduction; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism
D008041:Linoleic Acids; D016859:Lipoxygenase Inhibitors; D012701:Serotonin; D019787:Linoleic Acid; D006861:Hydrogen Peroxide; D008084:Lipoxygenase; D004298:Dopamine; D009638:Norepinephrine