• Applied Chemistry for Engineering
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• v.7 no.5
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• pp.888-901
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• 1996

Oxidations of cyclopentene and of 1-pentene with air have been studied on a V/Mo/P/Al/Ti-mixed oxide catalyst in a fixed bed integral reactor. At high levels of conversion maleic anhydride was in each case produced as the major organic product, along with minor amounts of phthalic anhydride and, only starting from 1-pentene, also of citraconic anhydride. At lower levels of conversion a total of 30 organic products have been identified, some of which may be intermediates on the way from the substrates to the three anhydrides mentioned above. Based on the dependence of selectivities of the organic products on conversion, reaction schemes for the formation of maleic anhydride, phthalic anhydride and citraconic anhydride have been proposed. Oxidation at $310^{\circ}C$ led to increasing conversions and selectivities for maleic anhydride with decreasing space velocities. The highest selectivities for maleic anhydride were obtained at conversion of ca. 100%. Oxidation at a constant space velocity of $2{\cdot}10^4h^{-1}$ led to increasing conversions with increasing temperatures in the range of $300^{\circ}C{\sim}420^{\circ}C$, while the selectivity for maleic anhydride passed through a maximum value of ca. 39% at $370^{\circ}C$ in the oxidation of cyclopentene and a maximum value of ca. 30% at $400^{\circ}C$ in the oxidation of 1-pentene.

• Applied Chemistry for Engineering
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• v.26 no.1
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• pp.111-115
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• 2015

Two new analogs of bestatin were prepared from $\small{D}$-leucine and $\small{D}$-valine in a stereoselective and efficient way. An aminopeptidase inhibitor bestatin shows significant biological effects on immunomodulation and is marketed for the treatment of acute myelocytic leukemia. The key intermediates, trans-oxazolidine methyl esters 2a and 2b, were obtained with more than 20 to 1 stereoselectivity in a one-pot procedure by the three cascade reactions between N-hydroxymethyl protected ${\alpha}$-amino aldehydes (4a and 4b) and phenylsulfonylnitromethane ($PhSO_2CH_2NO_2$) and the following in-situ ozonolysis. Basic hydrolysis of 2a and 2b, and then the peptide coupling with $\small{L}$-Leu-OMe produced the protected derivatives of two new bestatin analogs, 3a and 3b, respectively. The new isobutyl and isopropyl analogs of bestatin (1a and 1b) were produced in overall 51% and 38% yields, respectively, with high stereoselectivity from the corresponding protected ${\alpha}$-amino aldehydes 4 in a six-step process.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.6
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• pp.528-532
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• 2004

We have studied physiological responses of mung bean sprout to the treatment of elicitors. Chemicals such as salicylic acid and methyl jasmonic acid are not only the intermediates found in plant defense system but also could affect plant secondary metabolism. We found that mild treatment of salicylic acid and acetyl salicylic acid (aspirin) increase isoflavone production dramatically in mung bean sprout which has very low level of isoflavones compared with soybean sprout. The isoflavone content in salicylic acid treated- and acetyl salicylic acid treated-mung bean sprout was about 2.3 and 2.2 times higher than that of control, respectively. However, the increasing patterns of isoflavone in cotyledon and hypocotyl and root were not identical. The major increase among isoflavone fractions in cotyledon was led by the increase in malonylglycitin and malonyldaidzin level. Whereas, the increase in hypocotyl and root was led by malonyldaidzin. Methyl jasmonic acid did not show statistically significant increase in mung bean sprout. With this result, we were able to propose the non-transgenic method, which can control the isoflavone production in germinating mung bean.

• Parasites, Hosts and Diseases
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• v.31 no.3
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• pp.259-268
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• 1993

When activity of peroxidase in auld Pnrqfonimn westermqni was monitored using o-dianisidine and $H_2O_2$ as substrates, its specific activity was 1.5 times higher In excretory-secretory product (ESP) than in crude extract. The one was purified by two purification steps of Sephacryl S-300 Superfine gel permeation and DEAE-Trisacryl M anion exchange chromatographies. Its activity increased 16.9 fold with 32.3% recovery. The enzyme was inhibited totally by 1 millimoles of dithiothreitol (DTT), 2-mercaptoethanol and azide. Molecular mass was 16 kDa in reducing SDS-polyacrylamide gel electrophoresis (PAGE) or 19 kDa in TSK-Blue gel filtration high performance liquid chromatography (HPLC). respectively. Special staining for peroxidase by diaminobenzidine on SDS-PAGE confirmed the activity. The peroxidase was less reactive to a paragonimiasis serum when observed by SDS-PAGE/immunoblot. In addition, specific activities of superoxide dismutase (SOD) and catalase were also identified in the ESP. High activities of these antioxidant enzymes in ESP indicate that they are parts of defense mechanisms against reactive oxygen intermediates from host.

• The Korean Journal of Mycology
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• v.27 no.6 s.93
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• pp.406-411
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• 1999

The phylogenetic relationships of black-spored basidioid taxa (mainly coprinoid taxa) and an agaric-like gastroid taxon were studied. The sequences of internal transcribed spacer regions (ITS) partially including 17S, 25S and 5.8S from 14 species (Coprinus comatus, C. atramentarius, C. micaceus, C. cinereus, C. disseminatus, C. rhizophorus, C. radians, C. echinosporus, Psathyrella candolleana, Podaxis pistillaris, Conocybe lactea, Bolbitius demangei, Agaricus balzei, and Stropharia rugosoannulata) were compared. The reciprocal homologies of ITS sequences among these species were in the range of $38.7{\sim}77.2%$. Black-spored taxa were classified into four clusters. Cluster I comprised C. micaceus, C. radians, and C. disseminata. Cluster II is consisted of C. cinereus, C. echinosporus, C. rhizophorus, and C. atramentarius. On the other hand, C. comatus is in cluster III with Agaricus balzei and Podaxis pistillaris even though this species is belonging to the section Coprinus in morphological aspect. Psathyrelloid taxon is included in cluster II. The question of the origin of secotioid (agaric-like) fungi has been taken, though largely on theoritical suggestions as to whether gastroid taxa give rise to agarics with secotioid taxa as intermediates or whether secotioid taxa are evolutionary novelities arising from many distinct groups of agarics. In this relationship, it was shown that secotioid taxon evolved from within agaric species.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2002.10a
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• pp.18-25
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• 2002

The pikromycin biosynthetic system in Streptomyces venezuleae is unique for its ability to produce two groups of antibiotics that include the 12-membered ring macrolides methymycin and neomethymycin, and the 14-membered ring macrolides narbomycin and pikromycin. The metabolic pathway also contains two post polyketide-modification enzymes, a glycosyltransferase and P450 hydroxylase that have unusually broad substrate specificities. In order to explore further the substrate flexibility of these enzymes a series of hybrid polyketide synthases were constructed and their metabolic products characterized. The plasmid-based replacement of the multifunctional protein subunits of the pikromycin PKS in S. venezuelae by the corresponding subunits from heterologous modular PKSs resulted in recombinant strains that produce both 12- and 14-membered ring macrolactones with predicted structural alterations. In all cases, novel macrolactones were produced and further modified by the DesVII glycosyltransferase and PikC hydroxylase leading to biologically active macrolide structures. These results demonstrate that hybrid PKSs in S. venezuelae can produce a multiplicity of new macrolactones that are modified further by the highly flexible DesVII glycosyltransferase and PikC hydroxylase tailoring enzymes. This work demonstrates the unique capacity of the S. venezuelae pikromycin pathway to expand the toolbox of combinatorial biosynthesis and to accelerate the creation of novel biologically active natural products. The polyketide backbone of rifamycin B is assembled through successive condensation and ${\beta}$-carbonyl processing of the extender units by the modular rifamycin PKS. The eighth module, in the RifD protein, contains nonfunctional DH domain and functional KR domain, which specify the reduction of the ${\beta}$-carbonyl group resulting in the C-21 bydroxyl of rifamycin B. A four amino acid substitution and one amino acid deletion were introduced in the putative NADPH binding motif in the proposed KR domain encoded by rifD. This strategy of mutation was based on the amino acid sequences of the corresponding motif of the KR domain of module 3 in the RifA protein, which is believed dysfunctional, so as to introduce a minimum alteration and retain the reading frame intact, yet ensure loss of function. The resulting strain produces linear polyketides, from tetraketide to octaketide, which are also produced by a rifD disrupted mutant as a consequence of premature termination of polyketide assembly. Much of the structural diversity within the polyketide superfamily of natural products is due to the ability of PKSs to vary the reduction level of every other alternate carbon atom in the backbone. Thus, the ability to introduce heterologous reductive segments such as ketoreductase (KR), dehydratase (DH), and enoylreductase (ER) into modules that naturally lack these activities would increase the power of the combinatorial biosynthetic toolbox. The dehydratase domain of module 7 of the rifamycin PKS, which is predicted to be nonfunctional in view of the sequence of the apparent active site, was replaced with its functional homolog from module 7 of rapamycin-producing polyketide synthase. The resulting mutant strain behaved like a rifC disrupted mutant, i.e., it accumulated the heptaketide intermediate and its precursors. This result points out a major difficulty we have encountered with all the Amycolatopsis mediterranei strain containing hybrid polyketide synthases: all the engineered strains prepared so far accumulate a plethora of products derived from the polyketide chain assembly intermediates as major products instead of just analogs of rifamycin B or its ansamycin precursors.

• Journal of Microbiology and Biotechnology
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• v.14 no.6
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• pp.1256-1266
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• 2004

2-Bromooctanoic acid (2-BrOA) is known to block the formation of polyhydroxyalkanoic acid (PHA) in Pseudomonasfluorescens BM07 without any influence on the cell growth when grown on fructose, but it inhibits the cell growth when grown on octanoate (OA) (Lee et al., Appl. Environ. Microbiol. 67: 4963- 4974, 2001). We investigated the role of 2-BrOA in the PHA synthesis of the bacterium grown with mixtures of fructose and fatty acids. OA, 11­phenoxyundecanoic acid (1 1-POU), and 5-phenylvaleric acid (5-PV) were selected as model substrates. When supplemented with 50 mM fructose, all these carboxylic acids suppressed the formation of PHA from fructose, however, the ~-oxidation coenzyme A monomers derived from the carboxylic acids were efficiently polymerized, but the conversion yield [(mol of carboxylate substrate converted into PHA)/(mol of carboxylate substrate in the feed)] was low (e.g., maximally $\~53\%$ for 5 mM 11-POU). Addition of 2-BrOA (up to 5 mM) to the mixed carbon sources raised the conversion yield sensitively and effectively only at low levels of the acid substrates (e.g., 2 mM 1 1-POU or 5 mM OA): For instance, $100\%$ of 2 mM ll-POU were converted into PHA in the presence of 5 mM 2-BrOA, whereas only $\~10\%$ of the 1 1-POU were converted in the absence of 2-BrOA. However, at highly saturated suppressing levels (e.g., 5 mM ll-POU), 2-BrOA inhibitor showed no significant additional effect on the conversion ($60- 70\%$ conversion irrespective of 2-BrOA level). The existence of competitive and compensative relationship between 2­BrOA and all the carboxylic acid substrates used may indicate 'Present address: Section on Brain Physiology and Metabolism, Bldg. 10, Rm. 6N202, National Institute on Agmg, National Institute of Health, Bethesda, MD 20892, U.S.A. that all the acid substrate-derived inhibiting species bind to the same site as the 2-BrOA inhibiting species does. We, therefore, suggest that 2-BrOA can be used for efficiently increasing the yield of conversion of expensive substituted fatty acids into PHA and then substituted 3-hydroxyacids by hydrolyzing it.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1174-1179
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• 2005

Up-flow sludge blanket(USB) reactors were used to investigate the effects of N/C(${NO_3}^--N/COD$) ratio on simultaneous denitrification and methanogenesis processes. Without nitrate feeding, 84% of the influent COD was converted into methane. With the increase of N/C ratio, nitrogen gas increased while methane production decreased and stopped finally at the N/C ratio over 0.20. Influent nitrate was completely denitrified into nitrogen gas while nitrate removal efficiency dropped below 40% at N/C ratio of 0.40 because of deficiency in organic carbon. Fraction of COD utilized by denitrification increased at higher N/C ratios. Methanogenesis started to be effected at N/C ratio of 0.05, which could explain the competition for organic carbon between these microorganisms such as denitrifiers and methanogens, rather than inhibitory effect of nitrate and its intermediates. Critical N/C ratio for simultaneous denitrification and methanogenesis was found to be 0.20. Influent COD was removed over 92% by denitrification, methanogenesis and other biochemical reactions including cell growth at these N/C ratios.

• Environmental Engineering Research
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• v.23 no.2
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• pp.181-188
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• 2018

Photocatalytic oxidation in the presence of Fe-doped, Zn-doped or Fe-Zn co-doped $TiO_2$ was used to effectively decompose humic acids (HAs) in water. The highest HAs removal efficiency (65.7%) was achieved in the presence of $500^{\circ}C$ calcined 0.0010% Fe-Zn co-doped $TiO_2$ with the Fe:Zn ratio of 3:2. The initial solution pH value, inorganic cations and anions also affected the catalyst photocatalytic ability. The HAs removal for the initial pH of 2 was the highest, and for the pH of 6 was the lowest. The photocatalytic oxidation of HAs was enhanced with the increase of the $Ca^{2+}$ or $Mg^{2+}$ concentration, and reduced when concentrations of some anions increased. The inhibition order of the anions on $TiO_2$ photocatalytic activities was $CO{_3}^{2-}$ > $HCO_3{^-}$ > $Cl^-$, but a slightly promotion was achieved when $SO{_4}^{2-}$ was added. Total organic carbon (TOC) removal was used to evaluate the actual HAs mineralization degree caused by the $500^{\circ}C$ calcined 0.0010% Fe-Zn (3:2) co-doped $TiO_2$. For tap water added with HAs, the $UV_{254}$ and TOC removal rates were 57.2% and 49.9%, respectively. The $UV_{254}$ removal efficiency was higher than that of TOC because of the generation of intermediates that could significantly reduce the $UV_{254}$, but not the TOC.

• The Korean Journal of Pharmacology
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• v.18 no.1
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• pp.55-63
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• 1982

Lipid peroxidation is the reaction of oxidative deterioration of polyunsaturated lipids and this peroxidation involves the direct reaction of oxygen and lipid to form free radical intermediates, which can lead to autocatalysis. As results of the extensive studies on the lipid peroxidation by many authors, the relationship between lipid peroxidation and the drug metabolizing system as well as the actions of free radicals on the peroxidation was reasonably well known. For a long time, the mechanism of hepatotoxicity of $CCl_4$ was not clearly understood. However, it is now quite well established that $CCl_4$ is activated in vivo to a free radical which is a highly reactive molecule. Therefore, lipid peroxidation which induces the reduction of cytochrome P-450 and aminopyrine demethylase activity is known as decisive event of $CCl_4$ hepatotoxicity. On the other hand, it was also reported that singlet molecular oxygen produces lipid peroxidation in liver microsomes. In this study the effects of benzoyl peroxide on the lipid peroxidation and drug-metabolizing enzyme were examined. Benzoyl peroxide mixed with starch and phosphates etc. is usually used as a food additive for flour bleaching and maturing purpose because of its oxidative property. Albino rats were used for the experimental animals. Benzoyl peroxide was suspended in soybean oil and sesame oil and administered intraperitoneally or orally. TBA value and aminopyrine demethylase activity were determined in liver microsomal fraction and serum. The results were summerized as following. 1) Body weights of animals administered benzoyl peroxide suspension were decreased while that of oil administered group were increased. 2) The activity of aminopyrine demethylase was generally decreased in animals administered oil suspension of benzoyl peroxide. Furthermore, the marked reduction of the enzyme activity was observed in animals administered benzoyl peroxide intraperitoneally. 3) Generally, microsomal TBA values as well as serum TBA were significantly elevated in benzoyl peroxide group in comparison with the control group. However, the more remarkable increase of serum TBA than microsomal TBA was observed in animals administered orally for 6 days. 4) Specifically, the changing pattern of TBA value was notable in serum rather than in liver microsome by intraperitoneal administration of benzoyl peroxide.