• BMB Reports
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• 제33권3호
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• pp.228-233
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• 2000

The steady-state investigation of the mechanism of Dhydroxyisovalerate dehydrogenase was performed in order to understand this type of kinetic patterns. The initial velocity was measured with various amounts of both substrates, NADPH and 2-ketoisovalerate. Double reciprocal plots gave patterns that conversed on or near the abscissa. Binding studies indicated that NADPH bound first to the enzyme. The product $NADP^+$ was found to be a competitive inhibitor with respect to NADPH at a constant concentration of 2-ketoisovalerate. However, it showed noncompetitive inhibition against 2-ketoisovalerate at a fixed amount of NADPH. Another product, D-hydroxyisovalerate, was a non-competitive inhibitor versus NADPH and 2-ketoisovalerate at constant levels of 2-ketoisovalerate and NADPH, respectively. These results were comparable with an ordered bi-bi mechanism, in which NADPH bound first to the enzyme, followed by the binding of 2- ketoisovalerate. $NADP^+$ is the last product to be released. The ordered reaction manner of D-hydroxyisovalerate dehydrogenase from 2-ketoisovalerate to D-hydroxyisovalerate allows the accurate regulation of valine metabolism and it may lead to the regulation of total biosynthesis of enniatins in the Fusarium species.

• Plant Biotechnology Reports
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• 제2권2호
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• pp.113-122
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• 2008

Nitric oxide (NO) affects the growth and development of plants and also affects plant responses to various stresses. Because NO induces root differentiation, we examined whether or not it is involved in increased ROS generation. Treatments with sodium nitroprusside (SNP), an NO donor, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), a specific NO scavenger, and $N{\omega}-nitro-{\text\tiny{L}}-arginine$ methyl ester hydrochloride (${\text\tiny{L}}-NAME$), an NO synthase (NOS) inhibitor, revealed that NO is involved in the adventitious root growth of mountain ginseng. Supply of an NO donor, SNP, activates NADPH oxidase activity, resulting in increased generation of $O_2{^{{\cdot}-}}$, which subsequently induces growth of adventitious roots. Moreover, treatment with diphenyliodonium chloride (DPI), an NADPH oxidase inhibitor, individually or with SNP, inhibited root growth, NADPH oxidase activity, and $O_2{^{{\cdot}-}}$ anion generation. Supply of the NO donor, SNP, did not induce any notable isoforms of enzymes; it did, however, increase the activity of pre-existing bands of NADPH oxidase, superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, and glutathione reductase. Enhanced activity of antioxidant enzymes induced by SNP supply seems to be responsible for a low level of $H_2O_2$ in the adventitious roots of mountain ginseng. It was therefore concluded that NO-induced generation of $O_2{^{{\cdot}-}}$ by NADPH oxidase seems to have a role in adventitious root growth of mountain ginseng. The possible mechanism of NO involvement in $O_2{^{{\cdot}-}}$ generation through NADPH oxidase and subsequent root growth is discussed.

• Journal of Acupuncture Research
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• 제18권2호
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• pp.79-90
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• 2001

Objective : The aim of the present study is to investigate whether stimulating a specific auricular point(胃點) is effect on suppression of appetite. Methods : This study evaluated the changes of Reduced-Nicotinamide-Adenine-inucieotide-Phosphate-diaphorase(NADPH-d)-positive neurons using a histoehemical method. Staining intensities of NADPH-d-positive neurons were assessed in a quantitative fashion using a microdensitometrical method based on optical density by means of an image analyzer. Results : The results show as follows ; 1. In the RSG/RSA, FRI/FR2, HL, PAR1 area, The optical density of NADPH-d-positive neurons of fasted group was significantly decreased in comparison to fed group. 2. In most cortical area, It was not significant statistically, But the optical density of NADPH-d-positive neurons of fed with auricular acupuncture group was decreased in comparison to fed group. 3. In most cortical area, It was not significant statistically, But fasted with auricular acupuncture group increased the optical density of NADPH-d-positive neurons comparison to fasted group. Conclusions : We conclude that stimulating the specific auricular points is able to effect on NO(Nitric Oxide)-expression in the brain cortex of sprague dawley rats, The results suggest that auricular acupuncture may be useful for controlling obesity.

• BMB Reports
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• 제30권3호
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• pp.182-187
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• 1997

The NADPH oxidase of phagocytes catalyzes the reduction of oxygen to $O_2^-$ at the expense of NADPH. The enzyme is dormant in resting neutrophils and becomes activated on stimulation. During activation, $p47^{phox}\;(\underline{ph}agocyte\;\underline{ox}idase\;factor)$, a cytosolic oxidase subunit, becomes extensively phosphorylated at a number of serines located between S303-S379. Oxidase activation can also be achieved by the addition of phosphorylated recombinant $p47^{phox}$ by protein kinase C in the cell-free system in the presence of $GTP{\gamma}S$. The cell-free activation is inhibited by wortmannin and LY294002. specific inhibitors of phosphatidylinositol 3kinase (PI 3-kinasel) These results indicate that PI 3-kinase may playa pivotal role in the activation of NADPH oxidase.

• 한국미생물·생명공학회지
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• 제17권6호
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• pp.552-555
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• 1989

Corynebacterium glutamicum의 NADPH-specific glutamate dehydrogenase를 이용하여 NADPH, NH$_4$Cl, $\alpha$-ketoglutarate의 기질에 대한 kinetics를 고찰하였다. 이들의 kinetic constants를 측정함으로서 정반응에로의 효소반응 기작은 첫번째 효소와 반응하는 기질이 NADPH 임을 확인할 수 있었다. Glutamate dehydrogenase 활성의 조절을 위한 metabolites의 효과를 고찰하여 본 결과 malate와 citrate 만이 효소에 억제 효과를 나타내었으며, potassium chloride는 효소활성에 가장 많은 영향을 주었다.

• BMB Reports
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• 제37권5호
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• pp.629-633
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• 2004

NADPH-cytochrome P450 reductase (CPR) transfers electrons from NADPH to cytochrome P450, and catalyzes the one-electron reduction of many drugs and foreign compounds. Various forms of spectrophotometric titration have been performed to investigate the electron-accepting properties of CPR, particularly, to examine its ability to reduce cytochrome c and ferricyanide. In this study, the reduction of 1,1-diphenyl-2-picrylhydrazyl (DPPH) by CPR was assessed as a means of monitoring CPR activity. The principle advantage of DPPH is that its reduction can be assayed directly in the reaction medium by a continuous spectrophotometry. Thus, electrons released from NADPH by CPR were transferred to DPPH, and DPPH reduction was then followed spectrophotometrically by measuring $A_{520}$ reduction. Optimal assay concentrations of DPPH, CPR, potassium phosphate buffer, and NADPH were first established. DPPH reduction activity was found to depend upon the strength of the buffer used, which was optimal at 100 mM potassium phosphate and pH 7.6. The extinction coefficient of DPPH was $4.09\;mM^{-1}\;cm^{-1}$. DPPH reduction followed classical Michaelis-Menten kinetics ($K_m\;=\;28\;{\mu}M$, $K_{cat}\;=\;1690\;min^{-1}$). This method uses readily available materials, and has the additional advantages of being rapid and inexpensive.

• 약학회지
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• 제55권6호
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• pp.485-491
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• 2011

Previously, we have reported that apigenin, a natural flavonoid found in a variety of vegetables and fruits, stimulated melanogenesis through the activation of $K^+-Cl^-$-cotransport (KCC) in B16 melanoma cells. In this study we investigated the possible involvement of reactive oxygen species (ROS) in the mechanism of apigenin-induced melanogenesis in B16 cells. Apigenin elevated intracellular ROS level in a dose-dependent manner. Treatment with various inhibitors of NADPH oxidase, diphenylene iodonium (DPI), apocynin (Apo) and neopterine (NP) significantly inhibited both the generation of ROS and melanogenesis induced by apigenin. In addition these inhibitors profoundly inhibited apigenin-induced $Cl^-$-dependent $K^+$ efflux, a hallmark of KCC activity. However, the apigenin-induced ROS generation was not significantly affected by treatment with a specific KCC inhibitor R-(+)-[(2-n-butyl-6,7-dichloro-2-cyclopentyl-2,3-dihydro-1-oxo-1H-inden-5-yl)oxy]acetic acid (DIOA). These results indicate that the ROS production may be a upstream regulator of the apigenin-induced KCC stimulation, and in turn, melanogenesis in the B16 cells. Taken together, these results suggest that the NADPH oxidase-mediated ROS production may play an important role in the apigenin-induced melanogenesis in B16 cells. These results further suggest that NADPH oxidase may be a good target for the management of hyperpigmentation disorders.

• Korean Journal of Acupuncture
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• 제24권4호
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• pp.221-231
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• 2007

목 적 : 본 연구의 목적은 시상하부에서 침처치에 대한 nitric oxide synthase (NOS)발현을 nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d)를 이용한 조직화학 염색법으로 관찰하였다. 실험방법 : 동물은 Balb/c (wild type) 와 Stat 4 knockout (KO) 생쥐를 사용하였다. 염증유도는 1% carrageenan 용액 (20ul/마리)을 발 뒤꿈치 표피에 주사하였고, 침 처치는 족삼리 (ST36)에 시침하였다. 침 처치 후 5시간까지 부종율을 부종측정기로 측정하였으며, 마지막으로 부종을 측정한 후 동물을 희생하여 뇌를 적출하여 고정하였다. 침에 대한 효과를 확인하기 위하여 NADPH-d 반응의 조직염색을 실시하였다. 염증유도와 그룹간의 유의성 검증은 one-way ANOVA를 사용하였다. 결 과 : 대조군인 Balb/c와 실험군인 stat4 KO 생쥐를 carrageenan으로 염증을 유도시에 대조군은 90%이상 유도된 반면, Stat4 KO 그룹은 50% 정도의 염증만이 유도되었다. 염증을 유도한 생쥐의 족삼리에 침 처치시 대조군은 1시간에서 약 40%정도 감소하였고 (P<0.05), Stat4 KO 실험군은 유의한 염증 감소율을 보이지 않았다. 시상하부의 lateral hypothalamic area (LHA)와 paraventricular nucleus (PVN)부위의 침에 대한 효과를 NADPH-d 에 양성으로 반응하는 세포수로 비교하여 다음과 같은 결과를 얻었다. (1) 대조군에서 염증 유도시 시상하부의 PVN는 NADPH-d 양성세포수가 감소하였고, LHA에서는 증가하였다. (2) 염증을 유도한 대조군에 침을 처치시 PVN은 세포수가 증가하였고, LHA에서는 감소하는 경향을 보였다. (3) 염증을 유도한 Stat4 KO 군에서는 시상하부의 PVN과 LHA부위 모두에서 NADPH-d 양성세포수가 감소하였고, 염증유도그룹에 침을 처치시 PVN과 LHA부위 모두에서 세포수가 증가함을 관찰 할 수 있었다. (4) 대조군과 실험군 모두에 salicylic acid로 비교하였더니 염증유도 효과 및 NADPH-d 세포 수에서 침 처치와 비슷한 결과를 나타내었다. 결 론 : 침은 염증을 유도한 생쥐에서 염증 감소에 유의한 효과가 있다. 염증을 유도한 Balb/c 와 Stat4 KO 생쥐에 침을 처치 시 시상하부의 NADPH-d 발현이 LHA부위와 PVN에서 서로 다르게 나타나는 것으로 나타난다. 이러한 현상은 침 효과가 시상하부의 위치에 대한 작용이 다르기 때문이라고 생각된다.

• BMB Reports
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• 제32권3호
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• pp.226-231
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• 1999

In vitro effects of acetone on cytochrome P450 (P450)-dependent benzo(a)pyrene (B(a)P) hydroxylation supported by cumene hydroperoxide (CuOOH) or NADPH/$O_2 $ systems were studied using 3-methylcholanthrene-pretreated rat liver microsomes. The maximal rate of B(a)P hydroxylation at constant concentration ($80\;{\mu}M)$ of the substrate was observed in the presence of $30\;{\mu}M$ CuOOH. However, at concentrations higher than $30\;{\mu}M$ CuOOH the hydroxylation rates were rapidly decreased. In contrast to CuOOH, at a concentration of $200\;{\mu}M$ NADPH, B(a)P hydroxylation rate reached a plateau. At concentrations higher than $200\;{\mu}M$ NADPH, the rates of substrate hydroxylation were maintained at the maximal rate with no inhibition. Acetone at 1% (v/v) enhanced both CuOOH- and NADPH/$O_2$-supported B(a)P hydroxylation at the optimal concentrations of the cofactors. At concentrations higher than 1% (v/v) acetone, substrate hydroxylation was sterero specific under the support of these two cofactors; it was strongly enhanced with $30\;{\mu}M$ CuOOH, but rather inhibited in the $200\;{\mu}M$> NADPH/$0_2 $ system. The lipid peroxidation rate induced during CuOOH-supported P450-dependent B(a)P hydroxylation was increased as CuOOH concentrations were increased. Acetone in the concentration range of 2.5~7.5%(v/v) inhibited lipid peroxidation during CuOOH supported B(a)P hydroxylation. The finding that CuOOH-supported B(a)P hydroxylation is greatly enhanced by acetone suggests that acetone may contribute more to the activation of oxygen (for the insertion of oxygen into the substrate) in the presence of CuOOH than with NADPH/$O_2$. Acetone may also contribute to the partial inhibition of destruction of microsomal membranes by lipid peroxidation.

• 한국미생물·생명공학회지
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• 제47권4호
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• pp.536-545
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• 2019

Cytochrome P450 (P450 or CYP) is involved in the metabolism of endogenous and exogenous compounds in most organisms. P450s have great potential as biocatalysts in the pharmaceutical and fine chemical industries because they catalyze diverse oxidative reactions using a wide range of substrates. The high-cost nicotinamide cofactor, NADPH, is essential for P450 reactions. Glucose-6-phosphate dehydrogenase (G6PDH) has been commonly used in NADPH-generating systems (NGSs) to provide NADPH for P450 reactions. Currently, only two G6PDHs from Leuconostoc mesenteroides and Saccharomyces cerevisiae can be obtained commercially. To supply high-cost G6PDH cost-effectively, we cloned the cytosolic G6PDH gene of Solanum lycopersicum (tomato) with 6xHis tag, expressed it in Escherichia coli, and purified the recombinant G6PDH (His-G6PDH) using affinity chromatography. In addition, enzymatic properties of His-G6PDH were investigated, and the His-G6PDH-coupled NGS was optimized for P450 reactions. His-G6PDH supported CYP102A1-catalyzed hydroxylation of omeprazole and testosterone by NADPH generation. This result suggests that tomato His-G6PDH could be a cost-effective enzyme source for NGSs for P450-catalyzed reactions as well as other NADPH-requiring reactions.