PubMed · 4122696
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M M Everett. 1973. Deamination by the diazotization-deazotization method.. https://doi.org/10.1007/bf01012039
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The role of NADPH reductase and cytochrome b5 on glutathione (GSH)-induced stimulation of P450 3A4 activity was investigated. GSH increased the Vmax of testosterone 6 beta-hydroxylation without changing the K(m) for testosterone whereas it decreased the K(m) for NADPH-P450 reductase. Addition of cytochrome b5 inhibited testosterone 6 beta-hydroxylation in the reconstituted system, depleting GSH, while it dramatically enhanced the rate of testosterone 6 beta-hydroxylation in the presence of GSH. Cumene hydroperoxide-mediated P450 3A4 activity, which is independent of NADPH-P450 reductase and cytochrome b5, was not affected by GSH. High concentration of GSH above 4 mM was inhibitory in the reconstituted systems. These results suggest that GSH increases the apparent affinity between P450 3A4 and NADPH-P450 reductase, and between P450 3A4 and cytochrome b5, but has no effect on the affinity between P450 3A4 and testosterone.
Fuel leakage from underground storage tanks is a major source of groundwater contamination. Although the toxicity of regulated compounds such as benzene, toluene, ethylbenzene, and xylene (BTEX) are well recognized, the cytotoxicity of their metabolites has not been studied extensively. In this study, Hela cells, propagated at 37 degrees C in an atmosphere of 5% CO2-95% air, served as a target for evaluation of cytotoxicity of BTEX metabolites 3-methylcatechol, 4-methylcatechol, 4-hydroxybenzoic acid, and 4-hydroxy-3-methoxybenzoic acid. The cells were exposed to different concentrations of the metabolites, which subsequently showed inhibition of cell growth and produced dose-related decreases in cell viability and cell protein content. The BTEX metabolites affected the levels of the polyamines spermidine, spermine, and putrescine, which are known to be important in cell proliferation. The cytotoxic effects for these BTEX metabolites to Hela cells were 3-methylcatechol > 4-methylcatechol > 4-hydroxy-3-methoxybenzoic acid > 4-hydroxybenzoic acid.
We assayed the tolerance to solvents of three toluene-degrading Pseudomonas putida strains and Pseudomonas mendocina KR1 in liquid and soil systems. P. putida DOT-T1 tolerated concentrations of heptane, propylbenzene, octanol, and toluene of at least 10% (vol/vol), while P. putida F1 and EEZ15 grew well in the presence of 1% (vol/vol) propylbenzene or 10% (vol/vol) heptane, but not in the presence of similar concentrations of octanol or toluene. P. mendocina KR1 grew only in the presence of heptane. All three P. putida strains were able to become established in a fluvisol soil from the Granada, Spain, area, whereas P. mendocina KR1 did not survive in this soil. The tolerance to organic solvents of all three P. putida strains was therefore assayed in soil. The addition to soil of 10% (vol/wt) heptane or 10% (vol/wt) propylbenzene did not affect the survival of the three P. putida strains. However, the addition of 10% (vol/wt) toluene led to an immediate decrease of several log units in the number of CFU per gram of soil for all of the strains, although P. putida F1 and DOT-T1 subsequently recovered. This recovery was influenced by the humidity of the soil and the incubation temperature. P. putida DOT-T1 recovered from the shock faster than P. putida F1; this allowed the former strain to become established at higher densities in polluted sites into which both strains had been introduced.