C. Chen, C. C. Lin
Dec 23, 1968
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0
Influential Citations
16
Citations
Quality indicators
Journal
Biochimica et biophysica acta
Abstract
1. 1. Tetralin and tetralin 1-hydroperoxide were chosen as model to study the mechanism of biological oxygenation. Both tetralin and tetralin hydroperoxide were converted to tetral-1-ol by rat liver supernatant fraction obtained at 10000 × g. Both the conversions of tetralin to tetralol and tetralin hydroperoxide to tetralol required NADPH. 2. 2. For the conversion of tetralin hydroperoxide to tetralol, ferrous sulfate, peroxidase, hemin, catalase and cytochrome c had no catalytic effect, whereas both boiled liver enzyme and hemoglobin had 30% of the activity of liver 10000 × g supernatant fraction. Boiled liver enzyme had no catalytic effect on the conversion of tetralin to tetralol. 3. 3. The optimal pH for the conversion of tetralin to tetralol was found to be between 6.0 and 7.6, while the optimal pH for the conversion of tetralin hydroperoxide to tetralol lay sharply between 6.8 and 7.0. 4. 4. For the conversion of tetralin to tetralol, a Km value of 6·10−4M, and a vmax value of 0.024 μg/min per mg protein were found. For the conversion of tetralin hydroperoxide to tetralol, a Km value of 3·10−4 M and a vax value of 0.087 μg/min per mg protein were obtained. 5. 5. Of the inhibitors at the concentrations studied, o-iodosobenzoate and mercuric chloride were the most effective in inhibiting the conversion of tetralin hydroperoxide to tetralol (>90%). They inhibited the conversion of tetralin to tetralol by 65% and 40% respectively. Sodium azide and carbon monoxide inhibited the conversion of tetralin to tetralol by 50%, but had no effect in inhibiting the conversion of tetralin hydroperoxide to tetralol. Other inhibitors had various effects. 6. 6. By the addition of p-chloromercuribenzoate (PCMB) or by the removal of NADPH, tetralin hydroperoxide was accumulated and detected in the hydroxylation of tetralin. 7. 7. These findings indicate that tetralin hydroperoxide can be an intermediate in the hydroxylation of tetralin to tetralol in rat-liver homogenate and eliminate the possibility of a mono-atomic oxygen species as a reactant in this reaction.