• Microbiology and Biotechnology Letters
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• v.38 no.3
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• pp.227-234
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• 2010

Cytochrome P450 enzymes which require the supply of electrons from NAD(P)H have a great biotechnological impact as they catalyze valuable reactions on a vast variety of substrates. However, very limited biotechnological application has been reported so far due to their functional complexity, limited stability (instability) and, in most cases, low catalytic activity. In this present review, we introduce some possibilities for improving their defect by exploring electron transport system and substrate flexibility in field of Streptomyces cytochrome P450.

• Korean Journal of Environmental Biology
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• v.23 no.1
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• pp.52-56
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• 2005

Eight days grown barley seedlings were treated with dimethipin for 72 hours and then the content of chlorophyll and photosynthetic electron activities of isolated chloroplasts were investigated. At the treatment of 10/sup -5/ M dimethipin the content of chlorophyll was decreased to 33% at 72 hours. Seven days etiolated barley seedlings were exposed to the light while dimethipin was added. At the time of 48 hours' greening chlorophyll content was reduced to 43% at 10/sup -4/M dimethipin and the chlorophyll a/b ratio was increased. In photosynthetic electron transport the activity of PSⅡ+PSⅠ was decreased to 10% at 48 hours and 25% at 72 hours at 10/sup -4/ M dimethipin. In the treatment of 10/sup -4/ M dimethipin the activity of PSⅡ+PSⅠ, except water splitting system was inhibited to 16% at 48 hours and 27% at 72 hours. The activity of PSⅡ was inhibited to 8% at 24 hours, 13% at 48 hours and 18% at 72 hours at 10/sup -4/ M dimethipin. The activity of PSⅠ was inhibited to 4% at 24 hours, 8% at 48 hours and 10% at 72 hours at 10/sup -4/ M dimethipin. In the times of greening of 7 days etiolated barley seedlings the activities of PSⅡ+PSⅠ were reduced to 5, 10, 10 and 11 % at 6, 12, 24, and 48 hours, respectively, at 10/sup -4/ M dimethipin. On the other hand, the activity of PSⅡ+PSⅠ except water splitting system, was not inhibited at all incubated hours in 10/sup -4/M dimethipin and there were no clear changes of the activities of PSⅡ and PSⅠ as compared to the control. Therefore, it could be concluded that dimethipin inhibited the photosynthetic electron activity by affecting the function of chloroplast rather than the synthesis of chloroplast and the inhibited function of chloroplast seems to come from the severe decrease of chlorophyll content.

• Journal of Plant Biology
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• v.31 no.3
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• pp.217-226
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• 1988

Effects of simazine [2-chloro-4,6-bis(methylamino)-s-triazine] on the photochemical reactions of isolaed spinach chloroplasts and crude thylakoids of Anabaena inequalis UTEX B-381 were compared. Simazine inhibited photosynthetic O2 evolution and increased the chlorophyll fluorescence in whole cells of Anabaena. The electron transfer from diphenylcarbazide to 2,6-dichlorophenolindophenol was inhibited by simazine treatment in spinach chloroplasts, but not in crude thylakoids of Anabaena. In spinach chloroplasts, the chlorophyll fluorescence was increased by simazine treatment in the presence of diphenylcarbazide and ferricyanide, but not in the presence of diphenylcarbazide and silicomolybdate. In crude thylakoids of Anabaena, simazine treatment did not increase the chlorophyll fluorescence in the presence of either diphenylcarbazide and silicomolybdate, or diphenylcarbazide and ferricyanide. There results suggest that the inhibitory site of simazine on photosynthetic electron transport chain of anabaena is different from that of spinach chloroplasts. And there may be a possiblity that the inhibition site of simazine in Anabaena lies on the donor side of photosystem II, before the site of electron donation by diphenylcarbazide.

• Journal of Plant Biology
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• v.26 no.2
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• pp.91-99
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• 1983

The formation of chlorophyll-protein complexes (CP-complexes) during the greening of rape cotyledons (Brassica napus cv. Yongdang) was investigated by the SDS-polyacrylamide gel electrophoresis. The total chlorophyll content and Chl a/b ratio were also determined. In addition, the effects of dark treatment on the CP-complex patterns during greening have been examined with respect to their photosynthetic electron transport activity. Greening has brought about the increasein total chlorophyll content and the decrease in Chl a/b ratio, but there have been no changes in Chl a/b ratio after 24 hrs of greening. The light-harvesting chlorophyll a/b-protein complex (LHCP-complex0 was predominant during the initial greening period. Thereafter, the amout of chlorophyll a-protein complex (CP I-complex) was gradually increased. Twenty-four-hr dark treatment immediately after illumination for 6 hrs and 12 hrs resulted in the increase of the Chl a/b ration and the CP I complex, otherwise the decrease of the LHCP-complex. The LHCP/CP I ratio was gradually decreased with further greening, and appeared no change after 48 hrs illumination. The investigation of the photosynthetic electron transport activity indicated that photosystem (PS) II activity (H2Olongrightarrowp-PD*＋FeCy**) did not change, but the activity of PS I was increased suddenly due to the dark treatment. The data suggests that the increase of CP I-complex may result in that of P-700, that is, the increase of PS I activity.

• BMB Reports
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• v.38 no.4
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• pp.481-485
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• 2005

The response of Spirulina (Arthrospira) platensis to high salt stress was investigated by incubating the cells in light of moderate intensity in the presence of 0.8 M NaCl. NaCl caused a decrease in photosystem II (PSII) mediated oxygen evolution activity and increase in photosystem I (PSI) activity and the amount of P700. Similarly maximal efficiency of PSII (Fv/Fm) and variable fluorescence (Fv/Fo) were also declined in salt-stressed cells. Western blot analysis reveal that the inhibition in PSII activity is due to a 40% loss of a thylakoid membrane protein, known as D1, which is located in PSII reaction center. NaCl treatment of cells also resulted in the alterations of other thylakoid membrane proteins: most prominently, a dramatic diminishment of the 47-kDa chlorophyll protein (CP) and 94-kDa protein, and accumulation of a 17-kDa protein band were observed in SDS-PAGE. The changes in 47-kDa and 94-kDa proteins lead to the decreased energy transfer from light harvesting antenna to PSII, which was accompanied by alterations in the chlorophyll fluorescence emission spectra of whole cells and isolated thylakoids. Therefore we conclude that salt stress has various effects on photosynthetic electron transport activities due to the marked alterations in the composition of thylakoid membrane proteins.

• YAKHAK HOEJI
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• v.31 no.6
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• pp.361-369
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• 1987

The four azo dyes such as Amaranth (FD & C Red No. 2), Tartrazine (FD & C Yellow No. 4), sunset Yellow (FD & C Yellow No. 5) and Allura red (FD & C Red No. 40) are currently employed as a food additives in Korea. In this study, the effects of these azo dyes on the hepatic microsomal mixed function oxidase systems in Rats. (i.e., Cyt. P-450, Cyt. b$_5$, NADPH cyt. c-reductase and azo reductase) were investigated. Furthermore, to determine the relationship among the electron transport systems, each level of azo reductase, Cyt. P-450 and NADPH cyt. c-reductase was measured upon the administration of phenobarbital (known as an inducer of Cyt. P-450), 3-methylcholanthrene (Known as an inducer of Cyt. P-448), CoCl$_2$ (inhibitor on Cyt. P-450) or $CCl_4$ (inhibitor on Cyt. P-450). The results of these studies are as follows; (1) The levels of Cyt. P-450 and Cyt. b$_5$ were decreased upon the administration of these azo dyes. (2) When the level of Cyt. P-450 was decreased, the azo reductase activity was also decreased. (3) These azo dyes did not show any significant effect on the level of NADPH cyt. c-reductase. (4) The administration of 3-methylcholanthrene resulted in the elevation of azo reductase activity. The 3-methylcholanthrene may be responsible for the induction of CO-insensitive electron transport system.

• BMB Reports
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• v.29 no.1
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• pp.58-62
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• 1996

The structural changes in the electron donor side of the PSII reaction center have been monitored since heat treatment ($45^{\circ}C$ for 5 min) of thylakoids is known to decrease the oxygen evolving activity. In heat-treated spinach chloroplast thylakoids, the inhibitory effect of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) on the electron transport activity of the PSII reaction center from diphenyl carbazide to dichlorophenolindophenol became reduced approximately 3.8 times and [$^{14}C$]-labeled DCMU binding on the D1 polypeptide decreased to 25~30% that of intact thylakoid membranes, implying that the conformational changes of the DCMU binding pocket, residing on the D1 polypeptide, occur by heat treatment. The accessibility of trypsin to the $NH_2$-terminus of the cytochrome b-559 ${\alpha}$-subunit, assayed with Western blot using an antibody generated against the synthetic peptide (Arg-68 to Arg-80) of the COOH-terminal domain, was also increased, indicating that heat-treatment caused changes in the structural environments near the stromal side of the cytochrome b-559 ${\alpha}$-subunit, allowing trypsin more easily to cleave the $NH_2$-terminal domain. Therefore, the structural changes in the electron donor side of the PSII reaction center complexes could be one of the reasons why the oxygen evolving activity of the heat-treated thylakoid membranes decreased.

• Journal of Plant Biology
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• v.36 no.3
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• pp.195-201
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• 1993

The room temperature fluorescence induction of chloroplasts was utilized as a probe to locate the site of inhibition by mercury, copper and zinc on PS II by mercury. Inhibitory effect of Hg2+ on electron transport activity was notable as compared with Cu2+ and Zn2+. At concentrations of HgCl2 over 50 $\mu$M, activities of PS II and whole-chain electron transport decreased more than 70%, while that of PS I decreased about 10~30%. This suggests that PS II is more susceptible to Hg2+ than PS I is. In the presence of diphenylcarbazide (DPC), 50 $\mu$M HgCl2 inhibited the reduction of dichlorophenolindophenol (DCPIP) about 50%. Addition of heavy metals induced marked decrease in maximal variable fluorescence/initial fluorescence [(Fv)m/Fo], but no changes in Fo. With various concentrations of heavy metals, changes of chlorophyll a fluorescence emitted by PS II showed gradual decrease in photochemical quenching (qQ), which indicates an increase in reduced state of electron acceptor, QA. Especially, the addition of HgCl2 caused a notable decrease of qQ. In the presence of 50 $\mu$M CuCl2, energy-depended quenching (qE) was completely reduced, whereas in the presence of 50 $\mu$M CuCl2 and ZnCl2 it was still remained. The above results are discussed on the effects of mercury in relation to water-splitting system and plastoquinone (PQ) shuttle system.

• BMB Reports
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• v.43 no.9
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• pp.614-621
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• 2010

Propamidine, an aromatic diamidine compound, is widely used as an antimicrobial agent. To uncover its mechanism on pathogenetic fungi, Botrytis cinerea as an object was used to investigate effects of propamidine in this paper. The transmission electron microscope results showed that the mitochondrial membranes were collapsed after propamidine treatment, followed that mitochondria were disrupted. Inhibition of whole-cell and mitochondrial respiration by propamidine suggested that Propamidine is most likely an inhibitor of electron transport within Botrytis cinerea mitochondria. Furthermore, the mitochondrial complex III activity were inhibited by propamidine.

• The Korean Journal of Pharmacology
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• v.23 no.2
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• pp.113-121
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• 1987

Local anesthetics were investigated for their effects on mitochondrial electron transport system, production of superoxide radical from submitochondrial particles and malondialdehyde production through lipid per oxidation. Local anesthetics had various effects on activities of enzymes in electron transport chain. The activities of NADH dehydrogenase, NADH oxidase and NADH-ubiquinone oxidoreductase were effectively inhibited by lidocaine, procaine and dibucaine but slightly influenced by cocaine. The activities of succinate dehydrogenase, succinate-cytochrome c oxidoreductase and succinate-ubiquinone oxidoreductase were inhibited by lidocaine and dibucaine, but the succinate oxidase activity was stimulated by local anesthetics. Both dihydroubiquinone-cytochrome c oxidoreductase and cytochrome c oxidase activities were inhibited by local anesthetics. In these reactions, the response of Complex I segment to local anesthetics was greater than other Complex segments. Local anesthetics inhibited both the superoxide production from submitochondrial particles supplemented with succinate or NADH and the enhanced production of superoxide radicals by antimycin. The malondialdehyde production by oxygen free radicals was inhibited by local anesthetics. These results suggest that the inhibition of superoxide and malondialdehyde production caused by local anesthetics may be brought by suppression of the electron transport in mitochondria at sites in or near complex I segment.