• Journal of Environmental Science International
• /
• v.25 no.1
• /
• pp.173-179
• /
• 2016

Leaf water and osmotic potential, chlorophyll content, photosynthetic rate, and electrolyte leakage were measured to evaluate tolerance to water stress in wild-type (WT) and transgenic tobacco plants (TR) expressing copper/zink superoxide dismutase (CuZnSOD) and ascorbate peroxidase (APX) in chloroplasts. Leaf water potential of both WT and TR plants decreased similarly under water stress condition. However, leaf osmotic potential of TR plants more negatively decreased in the process of dehydration, compared with WT plants, suggesting osmotic adjustment. Stomatal conductance (Gs) in WT plants markedly decreased from the Day 4 after withholding water, while that in TR plants retained relatively high values. Relatively low chlorophyll content and photosynthetic rate under water stress were shown in WT plants since $4^{th}$ day after treatment. In particular, damage indicated by electrolyte leakage during water stress was higher in WT plants than in TR plants. On the other hand, SOD and APX activity was remarkably higher in TR plants. These results indicate that transgenic tobacco plants expressing copper/zink superoxide dismutase (CuZnSOD) and ascorbate peroxidase (APX) in chloroplasts improve tolerance to water stress.

• BMB Reports
• /
• v.31 no.1
• /
• pp.70-76
• /
• 1998

The final step in ethylene biosynthesis is catalyzed by the enzyme 1-aminocyclopropane-1-carboxylate (ACC) oxidase. ACC oxidase was extracted from mung bean hypocotyls and its biochemical characteristics were determined. In vitro ACC oxidase activity required ascorbate and $Fe^{2+}$, and was enhanced by sodium bicarbonate. Maximum specific activity (approximately 20 nl ethylene $h^{-1}$ mg $protein^{-1}$) was obtained in an assay medium containing 100 mM MOPS (pH 7.5), $25\;{\mu}M$ $FeSO_4$, 6 mM sodium ascorbate, 1 mM ACC, 5 mM sodium bicarbonate and 10% glycerol. The apparent $K_m$ for ACC was $80{\pm}3\;{\mu}M$. Pretreating mung bean hypocotyls with ethylene increased in vitro ACC oxidase activity twofold. ACC oxidase activity was strongly inhibited by metal ions such as $Co^{2+}$, $Cu^{2+}$, $Zn^{2+}$, and $Mn^{2+}$, and by salicylic acid. Inactivation of ACC oxidase by salicylic acid could be overcome by increasing the $Fe^{2+}$ concentration of the assay medium. The possible mode of inhibition of ACC oxidase activity by salicylic acid is discussed.

• Journal of Nutrition and Health
• /
• v.14 no.3
• /
• pp.124-128
• /
• 1981

This study was carried out to understand the activity of pepsin, the proteolytic enzyme, to octapeptide (angiotensin II) in the presence of various synthetic antioxidants as food additives. 1) Dibutyl hydroxy toluene, butyl hydroxyanisole and ethyl protocathechuate did not influence the inhibitory activity of pepsin an the octapeptide as a substrate, but sodium-L-ascorbate inhibited pepsin activity at above 100ppm. However sodium L-ascorbate was completely removed after 30 minutes. 2) Pepsin brought about a quick break up the octapeptide, Asp-Arg-Val-Tyr-Ile-His-Gly-Phe, by splitting the Gly-Phe and Val-Tyr bond. 3) The melting point of synthetized octapeptide was $209-212^{\circ}C$, chemical formula and molecula weight were $C_{43}H_{65}N_{13}O_{12}{\cdot}CH_3COOH{\cdot}H_2O$ and 956.05, respectively. 4) The amino acid mole ratio of synthetized octapeptide by acid hydrolysis were Asp:0.98, Arg: 1.02, Val: 1.00. Tyr: 0.95, Ile: 1.00, His: 1.03, Gly: 0.96, Phe: 1.00.

• Journal of Microbiology and Biotechnology
• /
• v.28 no.7
• /
• pp.1217-1224
• /
• 2018

Seaweeds produce antioxidants to counteract environmental stresses, and these antioxidant genes are regarded as important defense strategies for marine algae. In this study, the expression of Pyropia yezoensis (Bangiales, Rhodophyta) ascorbate peroxidase (PyAPX) and manganese-superoxide dismutase (PyMnSOD) was examined by qRT-PCR in P. yezoensis blades under abiotic stress conditions. Furthermore, the functional relevance of these genes was explored by overexpressing them in Chlamydomonas. A comparison of the different expression levels of PyAPX and PyMnSOD after exposure to each stress revealed that both genes were induced by high salt and UVB exposure, being increased approximately 3-fold after 12 h. The expression of the PyAPX and PyMnSOD genes also increased following exposure to $H_2O_2$. When these two genes were overexpressed in Chlamydomonas, the cells had a higher growth rate than control cells under conditions of hydrogen peroxide-induced oxidative stress, increased salinity, and UV exposure. These data suggest that Chlamydomonas is a suitable model for studying the function of stress genes, and that PyAPX and PyMnSOD genes are involved in the adaptation and defense against stresses that alter metabolism.

• Analytical Science and Technology
• /
• v.8 no.4
• /
• pp.591-596
• /
• 1995

Enzyme multilayers composed of avidin and biotin-labeled enzymes were prepared on the surface of electrode, through a strong affinity between avidin and biotin (binding constant: ca $10^{15} M^{-1}$). The enzyme multilayers were useful for the improvement of the performance characteristies of enzyme sensors. The output current of the enzyme sensors depended linearly on the number of enzyme layers deposited. Thus, lactate oxidase (LOx) and alcohol oxidase (AlOx) were deposited after being modified with biotin for constructing enzyme sensors sensitive to L-lactate and ethanol respectively. It was also possible to deposit two different kinds of enzymes successively in a single multilayer. The glucose oxidase (GOx) and ascorbate oxidase (AsOx) were built into a multilayer structure on a Platinum electrode. The GOx, AsOx multilayer-modified electrode was useful for the elimination of ascorbic acid interference of the glucose sensor.

• Environmental Analysis Health and Toxicology
• /
• v.13 no.1_2
• /
• pp.1-9
• /
• 1998

The ROS-producing potency of chromium compounds of several oxidation states were determined in the H4 cells. $K_2Cr_2O_7$ as Cr (VI), synthetic Cr (V) compounds and Cr (III) as TPP produced high level of ROS. However, ROS values of Cr-picolinate as Cr (III), CrCl$_2$, CrCI$_2$, were almost equal to the control. The effects of physiological antioxidants compounds which react with free radicals were examined for their effects on chromate-induced production of reactive oxygen species (ROS) in A549 cells after the addition of $K_2Cr_2O_7$. The compounds used were vitamin C (ascorbate), vitamin E ($\alpha$-tocopherol), superoxide dismutase (SOD) and catalase. The preincubation of ascorbate (200uM) with A549 cells for 20hr resulted in a significant reduction of hexavalent chromate(100uM) induced ROS. However, there is no effects of preincubation of the cells with vitamin E succinate (10 and 20uM, 20hr) on the ROS production. Also, the effects of Cr (VI) on the cell cycle of A549 cells was measured by adding the DNA intercalating agent, propidium iodide. S phase of the cell cycle was increased by the chromium (VI) compounds up to 20uM indicating toxicity or possible mitogenic action of the cell. The shoulder in Go/G1 phase at 20uM Cr (VI) with 24 hr treatment indicates apoptosis.

• Proceedings of the Korean Biophysical Society Conference
• /
• 2003.06a
• /
• pp.70-70
• /
• 2003

Active sites and substrate bindings of 1-aminoxyclopropane-1-carboxylate oxidase (MD-ACO1) catalyzing the oxidative conversion of ACC to ethylene have been determined based on site-directed mutagenesis and comparative modeling methods. Molecular modeling based on the crystal structure of Isopenicillin N synthase (IPNS) provided MD-ACO1 structure. MD-ACO1 protein folds into a compact jelly roll shape, consisting of 9 ${\alpha}$-helices, 10 ${\beta}$-strands and several long loops. The MD-ACO1/ACC/Fe(II)/Ascorbate complex conformation was determined from automated docking program, AUTODOCK. The MD-ACO1/Fell complex model was consistent with well known binding motif information (HIS177-ASP179-HIS234). The cosubstrate, ascorbate is placed between iron binding pocket and Arg244 of MD-ACO1 enzyme, supporting the critical role of Arg244 for generating reaction product. These findings are strongly supported by previous biochemical data as well as site-directed mutagenesis data. The structure of enzyme/substrate suggests the structural mechanism for the biochemical role as well as substrate specificity of MD-ACO1 enzyme.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.12 no.2
• /
• pp.93-98
• /
• 1983

Apple sugaring and apple nectar gel were treated with coating agent, and then the rate of weight loss, browning reaction and fungi growth on the storage conditions of those were investigated. The results obtained were summarized as follows; The composition of sucrose, D-sorbitol, corn syrup, gelatin, arabia gum, citric acid, sodium citrate and sodium ascorbate as a nontoxic coating agent was desirable to repress weight loss browning reaction and fungi growth of apple sugaring and apple nectar gel. It was the most effective method that apple sugaring was treated with the coating agent and refrigerated with double packaging. The contraction by weight loss, browning reaction and fungi growth of apple nectar gel treated with the coating agent and freezed with double packaging were repressed.

• Analytical Science and Technology
• /
• v.29 no.4
• /
• pp.162-169
• /
• 2016

The purpose of this study was to compare the relative bioavailability of synthetic Vitamin C and Nutra-C^® (calcium ascorbate) using a randomized parallel pharmacokinetics study design. Under fasting conditions, 20 healthy volunteers were randomly allocated to receive a single oral dose (500 mg of ascorbic acid) of either synthetic Vitamin C or Nutra-C^®. Fasting blood was collected pre-dose and 1, 2, 3, 4, 7 and 10 hr post-dose. The ascorbic acid content of human serum was determined using HPLC with ultraviolet detection. The fasting serum ascorbic acid concentrations of synthetic Vitamin C and Nutra-C^® were 6.734 ± 2.09 ng/mL (n = 10) and 7.542 ± 2.96 ng/mL (n = 10), respectively. The bioavailability of Nutra-C^® was significantly greater (128 %, p < 0.05) than that of the synthetic Vitamin C.

• Nutritional Sciences
• /
• v.3 no.1
• /
• pp.36-41
• /
• 2000

The aim of this study was to evalute the effect of multivitamin-mineral supplementation during pregnancy on plasma levels of antioxidants, erythrocyte antioxidant enzyme activities, and lipid peroxidation. A controlled, semi-randomized, prospective trial was performed by comparing the supplement group, which received multivitamin-mineral tables once daily for 10 weeks, with the control group. Plasma levels of $\beta$-carotene, tocopherol, coenzyme Q10, ascorbate, folate, zinc, and selenium and malondialdehyde (MDA), as well as the activities of superocxide dismutase(SOD) and glutathione peroxidase(GSH-Px) in erythrocytes were measured initially (20 wk gestation) and at the end of the intervention (34 wk gestation). In the control group, plasma ascorbate and selenium levels decreased and tocopherol levels increased. In the supplement group, a significant increase in plasma $\beta$-carotene(46%), conenzyme Q10 (42%), and zinc (24%) was observed after 10 weeks of supplementation. No changes were observed in the plasma levels of MDA, and erythrocyte GSH-Px activity, while SOD activity increased in both control group and the supplement group during the intervention. These data suggest that multivitamin-mineral supplementation during pregnancy produced moderate increases in plasma $\beta$-carotens, coenzyme Q10, and zinc concentrations but the enhancement of those plasma antioxidants had on direct on the plasma level of MDA, erythrocytes SOD or GSH-Px activities.