• Title/Summary/Keyword: Nonenzymatic

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Nonenzymatic Sensor Based on a Carbon Fiber Electrode Modified with Boron-Doped Diamond for Detection of Glucose (보론 도핑 다이아몬드로 표면처리된 탄소섬유 기반의 글루코스 검출용 비효소적 바이오센서)

  • Song, Min-Jung
    • Korean Chemical Engineering Research
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    • v.57 no.5
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    • pp.606-610
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    • 2019
  • In this study, we demonstrated that the nonenzymatic glucose sensor based on the flexible carbon fiber bundle electrode with BDD nanocomposites (CF-BDD electrode). As a nano seeding method for the deposition of BDD on flexible carbon fiber, electrostatic self-assembly technique was employed. Surface morphology of BDD coated carbon fiber electrode was observed by scanning electron microscopy. And the electrochemical characteristics were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. This CF-BDD electrode exhibited a large surface area, a direct electron transfer between the redox species and the electrode surface and a high catalytic activity, resulting in a wider linear range (3.75~50 mM), a faster response time (within 3 s) and a higher sensitivity (388.8 nA/mM) in comparison to a bare CF electrode. As a durable and flexible electrochemical sensing electrode, this brand new CF-BDD scheme has promising advantages on various electrochemical and wearable sensor applications.

Distribution of Trypsin Indigestible Substrate (TI) in Seafoods and Its Changes during Processing 2. Changes in TI and In Vitro Apparent Digestibility of Boiled and Dried Anchovy during Processing and Storage (어패류의 Trypsin활성 저해물질의 분포와 가공중의 변화 2. 자건멸치 가공저장중의 Trypsin활성 저해물질과 In Vitro Apparent Digestibility의 변화)

  • LEE Kang-Ho;JO Jin-Ho;RYU Hong-Soo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.17 no.2
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    • pp.101-108
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    • 1984
  • In order to study the optimal conditions of processing and storage for boiled and dried anchovy (Engraulis japonica) with high protein digestibility, the contents of trypsin indigestible substrate (TI) and in vitro apparent protein digestibility were determined. Peroxide value (PoV), TBA number and nonenzymatic brown pigments, that accounted for important antinutritional factors, were also measured and confirmed the relationship between those factors and formation of TI or in vitro protein apparent digestibility. The results were as follows; Samples boiled for 5 minutes showed the lower content of TI than the other samples boiled for 0.5 min. or 1 min. Hot air dried products had a lower TI content in comparison with the other dried ones such as sun dried or freeze dried products. It was revealed that the lower temperature ($8{\pm}1^{\circ}C$) did not affect to a great degree of forming TI and falling in vitro digestibility comparing to high temperature ($26{\pm}1^{\circ}C$) during storage. The lowest TI content (0.173 mg/g solid) was noted in the samples for 5 minutes and then sun drying after 56 days storage at $9{\pm}1^{\circ}C$. A rapid decrease of in vitro protein digestibility occurred within 0.5 min. of boiling and showed the value $85.3\%$. Freeze dried samples possessed the highest in vitro protein digestibility ($85.9\%$), when compared to sun dried or hot air dried products. Fat oxidation and nonenzymatic browning were proceeded with the various boiling times, drying methods and storing temperatures. It was noted that boiling for 5 minutes and freeze drying accelerate the fat oxidation significantly. More nonenzymatic brown pigments was developed in samples boiled for shorter time (0.5 min.) and that stored at high temperature ($26{\pm}1^{\circ}C$) than the other products. Therefore, fat oxidation and nonenzymatic browning assumed to be a major inhibitory reaction in enzyme digestion and those might be an important role in forming TI in boiled and dried anchovy products during processing and storage.

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Distribution of Trypsin Indigestible Substrate(TI) in Seafoods and Its Changes during Processing 3. Changes in TI and Protein Quality of Salted and Dried Yellow Corvenia(Pseudosciaena manchurica) during Processing and Storage (어견류의 Trypsin활성 저해물질의 분포와 가공중의 변화 3. 염건조기 가공저장중의 TI 및 단백질품질변화)

  • LEE Kang-Ho;KWON Hae-Ran;RYU Hong-Soo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.17 no.2
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    • pp.109-116
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    • 1984
  • In order to assess the protein nutritional quality of salted and dried yellow corvenia, which was prepared using the different salting methods like dry and brine salting, the changes of trypsin indigestible substrate(TI) and in vitro apparent protein digestibility were studied during storage at room temperature($24{\pm}1^{\circ}C$). It was also examined the retention of available lysine and formation of nonenzymatic brown pigments under the same conditions of preparing and storage mentioned above and confirmed the relationship between in vitro digestibility and the antinutritional factors, such as nonenzymatic browning, unavailability of lysine and TI content, TI content was gradually increased during the storage and in showed $1.5{\sim}2$ times more after 57 days storage than at the initial stage which ranged from 0.11 to 0.17mg/g solid. Of all the products, $25\%$ brine salting product contained the least TI content in 0.21 mg/g solid, while $10\%$ dry salting products was the most abundant in 0.30 mg/g solid using Hamerstrand method(1981). In vitro protein digestibility of all dried products was decreased significantly up to 30 days as the contents of TI increased, except $25\%$ brine salted products. After storing for 57 days, the in vitro digestibility was only $4\%$ drip showed in $25\%$ brine salted products. The nonenzymatic brown pigments were also developed on the level of available lysine reduced as in vitro protein digestibility was decreased throughout storage. Of all the various salted and dried products of yellow corvenia, $25\%$ salting product showed the lowest rate of browning development and loss of available lysine. Therefore, it was revealed that unavailability of lysine and development of nonenzymatic brown pigments were major factors influencing the protein quality in salted and dried yellow corvenia.

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Glycation of Copper, Zinc-Superoxide Dismutase and its Effect on the Thiol-Metal Catalyzed Oxidation Mediated DNA Damage

  • Park, Jeen-Woo;Lee, Soo-Min
    • BMB Reports
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    • v.28 no.3
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    • pp.249-253
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    • 1995
  • The nonenzymatic glycation of copper, zinc-superoxide dismutase (Cu,Zn-SOD) led to inactivation and fragmentation of the enzyme. The glycated Cu,zn-SOD was isolated by boronate affinity chromatography. The formation of 8-hydroxy-2'-deoxyguanosine (8-OH-dG) in calf thymus DNA and the generation of strand breaks in pBhiescript plasmid DNA by a metal-catalyzed oxidation (MCO) system composed of $Fe^{3+}$, $O_2$, and glutathione (GSH) as an electron donor was enhanced more effectively by the glycated CU,Zn-SOD than by the nonglycated enzyme. The capacity of glycated Cu,Zn-SOD to enhance damage to DNA was inhibited by diethylenetriaminepentaacetic acid (DETAPAC), azide, mannitol, and catalase. These results indicated that incubation of glycated CU,Zn-SOD with GSH-MCO may result in a release of $Cu^{2+}$ from the enzyme. The released $Cu^{2+}$ then likely participated in a Fenton-type reaction to produce hydroxyl radicals, which may cause the enhancement of DNA damage.

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Purification and Characterization of Bacillus subtilis Protoporphyrinogen Oxidase and Pre-equilibrium Behavior During Oxidation of Protoporphyrinogen IX

  • Jeong, Eun-Ju;Han, Ok-Soo
    • BMB Reports
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    • v.34 no.1
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    • pp.39-42
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    • 2001
  • Previous studies indicate that B. subtilis protoporphyrinogen oxidase is poorly inhibited by diphenyl ether herbicides. To better understand the basis of this insensitivity, the enzyme was overexpressed as a soluble protein in E. coli, purified and characterized. The mechanism of oxidation of B. subtilis protoporphyrinogen IX was studied and the enzyme kinetic parameters were determined for protoporpyrinogen IX; $K_m$, and $k_{cat}$ were $6.3\;{\mu}M$ and $0.028\;h-^1$, respectively. The enzyme required flavin adenine dinucleotide as a cofactor and its activity was enhanced by 1 mM n-octylglucopyranoside. The nonenzymatic oxidation rate was dependent on the concentration of protoporphyrinogen IX, suggesting that the reaction involves a pre-equilibrium step followed by a rate-limiting step.

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Effects of Citrus Flavonoids on the Lipid Peroxidation Contents (감귤류 플라보노이드가 지질 과산화물 함량에 미치는 영향)

  • Cha, Jae-Young;Kim, Hyun-Jeong;Kim, Sung-Kyu;Lee, Yong-Jae;Cho, Young-Su
    • Food Science and Preservation
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    • v.7 no.2
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    • pp.211-217
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    • 2000
  • The effects of Citrus flavonoids, hesperetin, hesderidin, naringenin, and naringin, on nonenzymatic lipid peroxidation were studied in three different in vitro experimental models. Hesperetin showed the most antioxidant effect in this experimental condition by measuring the malondialdehyde production using the thiobarbiturate and thiocyanate methods, the lipid peroxidation of microsomal membranes, and DPPH (${\alpha},{\alpha}'-diphenyl-{\beta}-picrylhydrazyl$) method. The antioxidative activity of the flavonoid aglycone forms, hesperetin, Citrus aglycone flavonoid, suggest the most antioxidant effect in this experimental condition, and this effect indicate more potent in the aglycones than their corresponding glycosides.

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Crosslinking Reaction of Phenolic Side Chains in Silk Fibroin by Tyrosinase

  • Kang, Gyung-Don;Lee, Ki-Hoon;Ki, Chang-Seok;Park, Young-Hwan
    • Fibers and Polymers
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    • v.5 no.3
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    • pp.234-238
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    • 2004
  • Tyrosinase oxidizes the tyrosyl residues in silk fibroin (SF) with oxygen, resulting in the production of ο-quinone residues. Subsequently, the inter-or intramolecular crosslinks are formed by reaction with amino groups in through nonenzymatic process. The measurement of oxygen consumption proved that the tyrosyl residues in SF were mostly oxidized to quinone residues by tyrosinase. The reaction mechanisms were proposed in this study and the crosslinking reaction of ο-quinone residues and the enzymatic oxidation of tyrosyl residues could be confirmed by the measurements of UV, $^1$H-NMR and GFC.

Oxalic Acid Metabolism and Decay Characteristics of Tyromyces palustris (갈색부후균 Tyromyces palustris의 수산대사와 목질분해 특성)

  • Son, Dong-Weon;Lee, Dong-Heub;Oh, Jung-Soo
    • Journal of the Korean Wood Science and Technology
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    • v.23 no.4
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    • pp.54-59
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    • 1995
  • This experiment was carried out to evaluate the role of oxalic acid metabolism in the incipient decay of brown rotting, and to investigate the effects of various compositions of culture medium. Until 5days incubation, the amount of oxalic acid produced by Tyromyces palustris was increased, while pH was gradually decreased. The difference in oxalic acid production depending on carbon sources was not significant and the pH adjustment of media did not stimulate the production of oxalic acid. In this experiment, hemicellulose was hydrolyzed with 1% oxalic acid, so it is suggested that nonenzymatic acid hydrolysis of hemicelluloses might be involved in the process of incipient decay of brown-rot fungi.

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Antioxidatibe Mechanism of Total Saponin of Red Ginseng (홍삼 총 사포닌의 항산화작용 기전)

  • Kim, Jung-Sun;Nam, Kyu;Shim, Kyung-Hee;Kim, Kyu-Won;Im, Kwang-Sik;Chung, Hae-Young
    • Journal of Life Science
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    • v.6 no.1
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    • pp.48-55
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    • 1996
  • Oxygen free radicals are highly reactive molecules with unpaired electrons, which are produced with in aerobic cells in the course of normal metabolic events. Normally, aerobic cells are protected from the damage of free radicals by antioxidative enzymes such as superoxide dismutase (SOD), catalase, glutathione (GSH) peroxidase, GSH S-transferase and GSH reductase which scabvenge free radicals as well as nonenzymatic antioxidants such as ceruloplasmin, albumin and nontioxidants in order to elucidate antioxidative mechanisms of red ginseng. The treatment with total saponin of red ginseng significantly devreased the contents of malondialdehyde and total free radicals in the liver. On the other hand, total saponin of red ginseng significantly increased the activities of SOD, catalase and GSH reductase and nonprotein-SH level. These results suggest that total saponin of red ginseng exerts an antioxidative effect by increasing endogenous antioxidants.

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Oxidative Stress Resulting from Environmental Pollutions and Defence Mechanisms in Plants (환경오염(環境汚染)에 의한 산화(酸化)스트레스와 식물체(植物體)의 방어기작(防禦機作))

  • Shim, Sang-In;Kang, Byeung-Hoa
    • Korean Journal of Environmental Agriculture
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    • v.12 no.3
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    • pp.264-280
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    • 1993
  • The environmental pollutions were a serious problem in Korea recently. So many researcher have studied the effect of environmental pollution on plants and agro-ecosystem, but the basic mechanisms of environmental stresses were various. One of the important mechanisms was oxidative stress caused by active toxic oxygen. The toxic oxygen was generated by several stresses, abnormal temperature, many xenobiotics, air pollutants, water stress, fugal toxin, etc. In the species of toxic oxygen which is primary inducer of oxidative stresses, superoxide, hydrogen peroxide, hydroxyl radical and singlet oxygen were representative species. The scavenging systems were divided into two groups. One was nonenzymatic system and the other enzymatic system. Antioxidants such as glutathione, ascorbic acid, and carotenoid, have the primary function in defense mechanisms. Enzymatic system divided into two groups; First, direct interaction with toxic oxygen(eg. superoxide dismutase). Second, participation in redox reaction to maintain the active antioxidant levels(eg. glutathione reductase, ascorbate peroxidase, etc.).

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