• Proceedings of the Zoological Society Korea Conference
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• 1996.10a
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• pp.238.2-238
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• 1996

No Abstract, See Full Text

• Bulletin of the Korean Chemical Society
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• v.19 no.8
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• pp.875-878
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• 1998

• Toxicological Research
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• v.3 no.1
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• pp.1-8
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• 1987

In vitro induction of cytochrome 450 associated monooxygenase activities by phenobarbital (PB) and 3-methylcholanthrene (MC) was investigated in primary cultures of adult rat hepatocytes. PB and MC were added to the culture 24 hr after the initial plating of hepatocytes. A signiftcant increase of the activities of 7-ethoxycoumarin 0-deethylase and aryl hydrocarbon hydroxylase were observed in MC and PB treated culture. MC caused about 500% induction of the initial oxidation rates of both enzymes in 48 hr. However the PB maintained both enzyme activities close to the level of freshly isolated hepatocytes. Biphenyl 4-hydroxylase and aminopyrine N-demethylase activities were also induced by MC and PB. But the level of induction was less than that occuring with 7-ethoxycoumarin 0-deethylase and aryl hydrocarbon hydroxylase. When aflatoxin $B_1$ was added to the hepatocyte cultures which have been treated with MC or PB, it caused a significant increase of the unscheduled DNA synthesis at higher dose of aflatoxin $B_1$ as compared to those of untreated control hepatocyte cultures. The results suggest that microsomal enzyme activities can be selectively controlled preferably in hepatocyte cultures by the in vitro induction method. This principle may be useful for studying the metabolism and other toxicological studies.

• KSBB Journal
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• v.14 no.3
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• pp.291-296
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• 1999

Chiral epoxides are key intermediates for the production of chiral pharmaceuticals, agrochemicals, and functional food additives. Chiral epoxides can be produced by either chemical or biological method. In biocatalytic production routes, chiral epoxides can be produced via epoxidations of prochiral alkenes by monooxygenase or peroxidase. Kinetic resolution of racemic epoxides using whole cells of bacteria or fungi might be commercially useful, since it is possible to obtain chiral epoxides with high optical purities from relatively cheap and readily avaiable racemic epoxides. Some bioprocesses already are commercially developed: the biocatalytic production of chiral epichlorohydrin via microbial stereospecific dehalogenation, and lipase-catalyzed enantioselective hydrolysis in a hollow fiber membrane bioreactor for the production of chiral methyl trans-3-(4-methoxyphenyl)glycidate. the intermediate for calcium antagonist diltiazem. The importance of biocatalytic production of chiral epoxides with several examples from literature are presented.

• Journal of Microbiology and Biotechnology
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• v.26 no.12
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• pp.2076-2086
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• 2016

Fungal cytochrome P450 (CYP) enzymes catalyze versatile monooxygenase reactions and play a major role in fungal adaptations owing to their essential roles in the production avoid metabolites critical for pathogenesis, detoxification of xenobiotics, and exploitation avoid substrates. Although fungal CYP-dependent biotransformation for the selective oxidation avoid organic compounds in yeast system is advantageous, it often suffers from a shortage avoid intracellular NADPH. In this study, we aimed to investigate the use of bacterial glucose dehydrogenase (GDH) for the intracellular electron regeneration of fungal CYP monooxygenase in a yeast reconstituted system. The benzoate hydroxylase FoCYP53A19 and its homologous redox partner FoCPR from Fusarium oxysporum were co-expressed with the BsGDH from Bacillus subtilis in Saccharomyces cerevisiae for heterologous expression and biotransformations. We attempted to optimize several bottlenecks concerning the efficiency of fungal CYP-mediated whole-cell-biotransformation to enhance the conversion. The catalytic performance of the intracellular NADPH regeneration system facilitated the hydroxylation of benzoic acid to 4-hydroxybenzoic acid with high conversion in the resting-cell reaction. The FoCYP53A19+FoCPR+BsGDH reconstituted system produced 0.47 mM 4-hydroxybenzoic acid (94% conversion) in the resting-cell biotransformations performed in 50 mM phosphate buffer (pH 6.0) containing 0.5 mM benzoic acid and 0.25% glucose for 24 h at $30^{\circ}C$. The "coupled-enzyme" system can certainly improve the overall performance of NADPH-dependent whole-cell biotransformations in a yeast system.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.3
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• pp.157-162
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• 2003

Our earlier studies found a significant correlation between the activities of ranitidine N-oxidation catalyzed by hepatic flavin-containing monooxygenase (FMO) and the presence of mutations in exon 4 (E158K) and exon 7 (E308G) of the FMO3 gene in Korean volunteers. However, caffeine N-1 demethylation (which is also partially catalyzed by FMO) was not significantly correlated with these FMO3 mutations. In this study, we examined another common mutation (V257M) in exon 6 of FMO3 gene. The V257M variant, which is caused by a point mutation (G769A), was commonly observed (13.21% allele frequency) in our subjects (n=159). This point mutation causes a substitution of $Val^{257}$ to $Met^{257}$, with transformation of the secondary structure. The presence of this mutant allele correlated significantly with a reduction in caffeine N-1-demethylating activity, but was not correlated with the activity of N-oxidation of ranitidine. In a family study, the low FMO activity observed in a person heterozygous for a nonsense mutation in exon 4 (G148X) and heterozygous for missense mutation in exon 6 (V257M) of FMO3 was attributed to the mutations. Our results suggest that various point mutations in the coding regions of FMO3 may influence FMO3 activity according to the probe substrates of varying chemical structure that correlate with each mutation on the FMO3 gene.

• Applied Biological Chemistry
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• v.38 no.5
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• pp.463-467
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• 1995

In vitro metabolism study of ${\alpha}$-endosulfan by liver and kidney microsomal cytochrome P-450 monooxygenase system of the mouse(Balb/C) was performed. ${\alpha}$-Endosulfan was metabolized to endosulfan lactone(EL), endosulfan hydroxyether(EHE), endosulfan alcohol(EA), endosulfan sulfate(ES), endosulfan ether(EE) and ${\beta}$-endosulfan(${\beta}$-E). The main metabolites of ${\alpha}$-endosulfan were EL(13.2%) and EA(11.5%) in liver microsome and EA(17.4%) md EHE(19.3%) in kidney microsome. The $^{14}C$-activity of organic extractable fraction and water soluble fraction were 63.4% and 31.7% in liver micosome incubates respectively. The water soluble metabolites were EA(83.9%), EHE(4.5%) and ES(2.3). Piperonyl butoxide treatment inhibited the formation of EE by 86%, EA by 92% and EHE, EL and ES were barely formed.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.6
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• pp.530-537
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• 2006

Recently isolated, Pseudomonas putida SN1 grows on styrene as its sole carbon and energy source through successive oxidation of styrene by styrene monooxygenase (SMO), styrene oxide isomerase (SOI), and phenylacetaldehyde dehydrogenase. For the production of (S)-styrene oxide, two knockout mutants of SN1 were constructed, one lacking SOI and another lacking both SMO and SOI. These mutants were developed into whole-cell biocatalysts by transformation with a multicopy plasmid vector containing SMO genes (styAB) of the SN1. Neither of these self-cloned recombinants could grow on styrene, but both converted styrene into an enantiopure (S)-styrene oxide (e.e. > 99%). Whole-cell SMO activity was higher in the recombinant constructed from the SOI-deleted mutant (130 U/g cdw) than in the other one (35 U/g cdw). However, the SMO activity of the former was about the same as that of the SOI-deleted SN1 possessing a single copy of the styAB gene that was used as host. This indicates that the copy number of styAB genes is not rate-limiting on SMO catalysis by whole-cell SN1.

• Journal of Applied Biological Chemistry
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• v.64 no.4
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• pp.433-438
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• 2021

Polyethylene is widely used as an agricultural film, but eco-friendly technology is lacking for its decomposition. Thus, recently, much attention has been paid to develop a technology for biological polyethylene decomposition. It has been expected that several oxidation steps will be required in the biological degradation of polyethylene. First, secondary alcohol is formed on the polyethylene chain, and then the alcohol is oxidized to a carbonyl group. In the subsequent process, the carbonyl group is converted to an ester by Baeyer-Villiger monooxygenase (BVMO), and this ester bond is expected to be cleaved by lipase and esterase in the final step. In this work, we reviewed BVMO as one of the promising enzymes for polyethylene decomposition, in terms of its reaction mechanism, classification, and engineering. In addition, we also give a brief perspective on polyethylene decomposition using BVMO.

• International Journal of Industrial Entomology and Biomaterials
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• v.43 no.1
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• pp.29-36
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• 2021

Silkworms have long been bred with human history to produce silk. It has been with humans for longer than other industrial insects, and the silkworm variety has been continuously improved. Silkworms have been developed into the optimal form for producing high quality silk and pupae. Recently, the production of transgenic silkworms has further expanded the possibility of industrial value of silkworms. Kynurenine 3-monooxygenase (KMO), which is a flavin enzyme, is known for its involvement in ommochrome pigment synthesis. In the field of mammals, including humans, previous studies have revealed the function and role of KMO, which is an important enzyme for various immune responses and cell protection. However, in the case of insects, the function of KMO has only been studied to be involved in the formation of pigment, and accordingly, KMO is used exclusively on screening for generation of transgenic insects as a marker. In this study, using KMO-edited silkworms, it was intended to discover the novel functions and roles of KMO in silkworms by identifying changes in the expression of various genes associated with stress and growth. The changes were observed in expressions of genes regulating on stresses to survive and those on ecdysteroid hormone between wild-type (WT) silkworms and kmo mutant silkworms. The loss of KMO, in particular, decreased the expression of the shadow (sad) gene, one of the Halloween genes in the synthesis of ecdysteroid. In conclusion, these results suggest that silkworm KMO is responsible for potential functions regarding stress response and ecdysteroid synthesis.