• Applied Biological Chemistry
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• v.41 no.4
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• pp.213-217
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• 1998

An assay for cytochrome P450 monooxygenase activity by determination of the products of organophosphate oxidation via inhibition of acetylcholinesterase was described. Extracts from strains of Oryzaephilus surinamensis selected for resistance to chlorpyrifos-methyl (QVOS 102), fenitrothion (VOS F) and malathion (VOS 3), and a standard susceptible strain VOS 48, were incubated with an organophosphate in the presence of a NADPH-generating system and acetylcholinesterase. The degree of inhibition of the acetylchoinesterase activity was converted to manooxygenase activity using standard curves for the inhibition of acetylcholiesterase by chlorpyrifos-methyl-oxon, fenitrooxon and malaoxan. Activity was detectable in VOS 48 and was present at different increased levels with the different organophosphates in the three resistant strains, suggesting that different forms of P450 might be involved in organophosphate oxidation in these insects. The assays were carried out using crude insect homogenates and much smaller samples of insect material than the standard aldrin to dieldrin assay. It should be possible to use the method for determination of monooxygenase activity in single insert.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.5
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• pp.591-595
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• 1997

An ex vivo assay determining the flavin-containing monooxygenase (FMO) activity in perfused rat liver has been developed by assessing the rate of thiobenzamide S-oxide (TBSO) formation from the infused thiobenzamide (TB). The hepatotoxicity by TB or TBSO was not a critical factor for maintaining the FMO activity for up to 50 min. The FMO activity expressed in nmoles TBSO produced/g liver/min was the same for the recycling and non-recycling perfusion. This implies that reduction of the oxidized TBSO back to the parent compound (TB) is negligible. Hydrolysis of the collected perfusates with either ${\beta}-glucuronidase$ or arylsulfatase did not increase the TBSO level and thus, TBSO does not appear to undergo conjugation either to glucuronide or sulfate esters. Thus, measuring the rate of TB S-oxidation in the isolated perfused liver with 1 mM TB for 50 min provides a useful tool for evaluation of the hepatic FMO activity in the absence of hepatic necrosis and without the interferences caused by further conjugation or back reduction of the TBSO to the parent TB.

• Environmental Analysis Health and Toxicology
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• v.15 no.4
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• pp.139-145
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• 2000

The Flavin-containing monooxygenase (FMOs) (EC1.14.13.8) are NADPH-dependent flavoenzymes that catalyze oxidation of soft nucleophilic heteroatom centers in a range of structurally diverse compounds, including foods, drugs, pesticides, and other xenobiotics. In humans, FMO3 is quantitatively a major human liver monooxygenase. In the present study, the baculovirus expression vector system was used to overexpress human FMO3 in insect cells for catalytic studies. Six commercially available organic selenium compounds were examined for substrate activity with microsomes isolated from Spodoptera frugiperda (Sf)9 cells infected with human FMO3 recombinant baculovirus. While none of the aromatic heterocyclic selenides tested showed detectable activity, all dialkyl- and alkylaryl-selenides free from ionic groups catalyzed the NADPH- and O$_2$-dependent oxidation. Kinetic constants demonstrate that (based on Km) dialkyl-and alkylaryl- selenides are better substrates for human FMO3 than analogous nitrogen or sulfur compounds .

• Korean Journal of Environmental Agriculture
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• v.9 no.2
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• pp.97-103
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• 1990

In order to determine the major biochemical degradation factors of the two organophosphorus insecticides, diazinon and dursban, the activities of monooxygenase(m. o.) and ${\alpha}$, ${\beta}-esterase$ were studied in submerged soil under laboratory conditions at $30{\pm}1^{\circ}C$ The degradation rate of diazinon by microorganism showed 1.5 times higher than dursban. The m. o. activity increased from 12hrs and 3days after application of diazinon and dursban, respectively. But the ${\beta}-esterase$ activity showed maximum at one day after application of dursban and $5{\sim}8$ days after diazinon application. Also, the ${\beta}-esterase$ activity was about 10 times higher than ${\alpha}-esterase$. Hence, it was concluded that the biological degradation of diazinon was mainly attributed to m. o. activity and the degradation of dursban to ${\beta}-esterase$ activity.

• Journal of the Korean Wood Science and Technology
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• v.39 no.6
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• pp.469-480
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• 2011

In this study, to determine the ligninase activity related to the PCBs degradation of Ceriporia sp. ZLY-2010, the protein contents and manganese peroxidase (MnP) and laccase activities during cultivation on shallow stationary culture (SSC) medium were observed. 4 PCB congeners were selected depending on the number of chlorine substituted on biphenyl. Furthermore, to examine the effects of cytochrome P450 monooxygenase, the inhibition of cytochrome P450 monooxygenase was evaluated by measuring the biodegradation rate when inhibitor such as 1-aminobenzotriazole was added. The extracellular protein contents were affected by PCB congeners in culture media. The total protein in the culture medium showed the biggest differences between the samples containing 2,2',4,4',5,5'-hexachlorobiphenyl and the control. On the other hand, MnP and laccase activity showed dominant increases within samples containing 4,4'-dichlorobiphenyl and 2,3',4',5-tetrachlorobiphenyl. Cytochrome P450 monooxygenase was inhibited by adding inhibitor, 1-aminobenzotriazole in low concentration. Only 2.73% of 2,3',4',5-tetrachlorobiphenyl was degraed on day 1, and biodegradation of 2,2',4,4',5,5'-hexachlorobiphenyl was inhibited as well, showing about 20% of biodegradation rate.

• Applied Biological Chemistry
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• v.39 no.1
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• pp.77-83
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• 1996

Effects of insecticide carbofuran and Phenobarbital sodium(PB) or 3-methylcholanthrene(3-MC) on activities of several enzymes in israeli carps were investigated. Survival number of Israeli carp was the same as that of control when PB and 3-MC only was treated, individually and that was low compared to control when carbofuran only was treated. But survival rate of Israeli carp was high compared to individual treatment of carbofuran when combination treatment of carbofuran and PB or 3-MC was carried out. These results indicate that PB and 3-MC can intervene to detoxify carbofuran exposed to israeli carp. In in vivo test for the effect of this chemicals on activity of enzyme in israeli carp, activities of acetylcholinesterase(AChE) and glutathione S-transferase(GST) were inhibited in carbofuran treatment, but did not in combination treatment of carbofuran and P3 or 3-MC. Activities of UDP-glucuronosyltransfe-rase (UDPGT) and cytochrome P-450-dependent monooxygenase increased in individual or combined treatments of carbofuran and PB or 3-MC. These results suggest that a simultaneous application of carbofuran and PB or 3-MC is critical for the enhancement of activity of AChE, GST, UDPGT and monooxygenase and the protection of Israeli carp from carbofuran toxicity.

• Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.261-265
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• 2013

The study was conducted to investigate the responses of the hepatic microsomal cytochrome P450 monooxygenase system in the rock bream Oplegnathus fasciatus after chronic exposure to 0, 1, 2, 4, and $8{\mu}g/L$ tributyltin (TBT) concentrations for 4 weeks. Hepatic cytochrome 450 content and ethoxyresorufin O-deethylation (EROD) activity were found to significantly increase in fish treated with the higher concentration of TBT (${\geq}4{\mu}g/L$); however, no significant changes were observed in penthoxyresorufin O-deethylation (PROD) activity in all treated groups compared to the control group. These findings suggest that exposure to a low TBT concentration (${\geq}4{\mu}g/L$) has the potential to induce cytochrome 450 content and EROD enzyme activity in hepatic tissue in the rock bream.

• Journal of Microbiology and Biotechnology
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• v.16 no.6
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• pp.974-978
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• 2006

The cytochrome P450 monooxygenase from the pikromycin biosynthetic gene cluster in Streptomyces venezuelae, known as PikC, was observed to hydroxylate the unnatural substrate indole to indigo. Furthermore, the site-directed mutagenesis of PikC monooxygenase led to the mutant enzyme F171Q, in which Phe171 was altered to Gln, with enhanced activity for the hydroxylation of indole. From enzyme kinetic studies, F171Q showed an approximately five-fold higher catalytic efficiency compared with the wild-type PikC. Therefore, these results demonstrate the promising application of P450s originating from Streptomyces, normally involved in polyketide biosynthesis, to generate a diverse array of other industrially useful compounds.

• Journal of Microbiology and Biotechnology
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• v.28 no.7
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• pp.1105-1111
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• 2018

The flavin-dependent monooxygenase Sam5 was previously reported to be a bifunctional hydroxylase with coumarate 3-hydroxylase and resveratrol 3'-hydroxylase activities. In this article, we showed the Sam5 enzyme has 3'-hydroxylation activities for methylated resveratrols (pinostilbene and pterostilbene), hydroxylated resveratrol (oxyresveratrol), and glycosylated resveratrol (piceid) as substrates. However, piceid, a glycone-type stilbene used as a substrate for bioconversion experiments with the Sam5 enzyme expressed in Escherichia coli, did not convert to the hydroxylated compound astringin, but it was converted by in vitro enzyme reactions. Finally, we report a novel catalytic activity of Sam5 monooxygenase for the synthesis of piceatannol derivatives, 3'-hydroxylated stilbene compounds. Development of this bioproduction method for the hydroxylation of stilbenes is challenging because of the difficulty in expressing P450-type hydroxylase in E. coli and regiospecific chemical synthesis.

• Korean Journal of Environmental Agriculture
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• v.9 no.2
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• pp.153-159
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• 1990

Two fractions(microsomal and soluble) were prepared by ultracentrifugation(105,000G for 1hr at $4^{\circ}C$) from pig liver in order to find the major factor in Diazinon degradation. The two enzyme activities showed the same value, but Diazinon was degraded three times in microsomal fraction more than in soluble fraction. And with addition of EPN, Beam and PBO, degradation of diazinon was inhibited(29, 30 and 60%) as well as Monooxygenase activity (14, 15 and 35%) in microsomal fraction, respectively.