• Applied Biological Chemistry
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• v.36 no.3
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• pp.158-162
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• 1993

A bilirubin oxidase produced by Penicillium sp. strain LAM 91-89 was purified and partially characterized. The enzyme was purified about 70 folds from culture broth by ethanol precipitation, first and second Sephadex G-200 column chromatography with overall yield of 12%. The molecular weight of the enzyme was estimated to be 53,000 dalton by SDS-PAGE. The optimum pH and temperature was 8.5 and $40^{\circ}C$, respectively. The enzyme was stable in the pH range $6{\sim}10$ and below $40^{\circ}C$. Activity of the enzyme was increased by the addition of $Mg^{2+}$ but was gretly inhibited by $Ag^+,\;Hg^{2+},\;Mn^{2+},\;Pb^{2+}$, iodoacetate, p-chloromercurobenzoic acid and sodium dodecyl sulfate. Among various substrates, bilirubin was favorably reacted and $K_m$ value for bilirubin was $6.67\;{\mu}mole$.

• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.373-378
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• 2021

The study aimed to develop a high-power enzymatic electrode for a wearable fuel cell that generates electricity utilizing lactate present in a sweat as fuel. Anode was fabricated by immobilizing lactate oxidase (LOx) on flexible carbon paper. As the lactate concentration in the electrolyte solution increased, the amount of current generated by catalysis of lactate oxidase increased. The immobilized LOx generated 1.5-times greater oxidation current density in the presence of gold nanoparticles than carbon paper only. Bilirubin oxidase (BOD)-immobilized cathode generated a larger amount of reduction current in the electrolyte saturated with oxygen than purged with nitrogen. A fuel cell composed of two electrodes was fabricated and cell voltage was measured under different discharge current. At the discharge current density of 66.7 ㎂/cm², the cell voltage was 0.5±0.0 V leading to maximum cell power density of 33.8±2.5 ㎼/cm².

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3118-3122
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• 2010

The water soluble redox polymer, poly(N-vinylimidazole) complexed with Os(4,4'-dichloro-2,2'-bipyridine)$_2Cl]^+$ (PVI-[Os(dCl-bpy)$_2Cl]^+$), was electrodeposited on the surface of a glassy carbon electrode by applying cycles of alternating square wave potentials between 0.2 V (2 s) and 0.7 V (2 s) to the electrode in a solution containing the redox polymer. The coordinating anionic ligand, $Cl^-$ of the osmium complex, became labile in the reduced state of the complex and was substituted by the imidazole of the PVI chain. The ligand substitution reactions resulted in crosslinking between the PVI chains, which made the redox polymer water insoluble and caused it to be deposited on the electrode surface. The deposited film was still electrically conducting and the continuous electrodeposition of the redox polymer was possible. When cycles of square wave potentials were applied to the electrode in a solution of bilirubin oxidase and the redox polymer, the enzyme was co-electrodeposited with the redox polymer, because the enzymes could be bound to the metal complexes through the ligand exchange reactions. The electrode with the film of the PVI-[Os(dCl-bpy)$_2Cl]^+$ redox polymer and the co-electrodeposited bilirubin oxidase was employed for the reduction of $O_2$ and a large increase of the currents was observed due to the electrocatalytic $O_2$ reduction with a half wave potential at 0.42 V vs. Ag/AgCl.

• Applied Chemistry for Engineering
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• v.24 no.1
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• pp.99-103
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• 2013

An emzymatic bioanode for a glucose/oxygen biofuel cell was prepared by the sequential coating of carbon nanotube (CNT), charge transfer complex (CTC) based on tetracyanoquinodimethane (TCNQ) and tetrathiafulvalene (TTF), glucose oxidase (GOx), and polyion complex (mixture of poly-L-lysine hydrobromide and poly (sodium 4-styrenesulfonate)) on a glassy carbon electrode. A biocathode was also prepared by the sequential coating of CNT, bilirubin oxidase (BOD), 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), and polyion complex. The effect of CNT and CTC on the electrochemical performance was investigated. The biofuel cell exhibited a promising performance with maximum power densities of 3.6, 10.1, and $46.5{\mu}W/cm^2$ at 5, 20, and 200 mM of glucose concentration, respectively. The result indicates that the biofuel cell architecture prepared in this study can be used in the development of biofuel cells and biosensors.

• Bulletin of the Korean Chemical Society
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• v.35 no.9
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• pp.2803-2808
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• 2014

High potential and fast electron transfer of a cathode mediator are significant factors for improving the performance of biofuel cells. This paper reports the first synthesis of a cathode redox polymer that is a coordination complex of poly (acrylic acid-vinylpyridine-acryl amide) (PAA-PVP-PAA) and [Os(4,4'-dicarboxylic acid-2,2'-bipyridine)$_2Cl_2]^{/+}$ ($E^{\circ}=0.48V$ versus Ag/AgCl). Bilirubin oxidase can be easily incorporated into this polymer matrix, which carried out the four-electron oxygen under typical physiological conditions (pH 7.2, 0.14 M NaCl, and $37^{\circ}C$). This new polymer showed an approximately 0.1 V higher redox potential than existing cathode mediators such as PAA-PVI-$[Os(dCl-bpy)_2Cl]^{+/2+}$. In addition, we suggest increasing the polymer solubility with two hydrophilic groups present in the polymer skeleton to further improve fast electron transfer within the active sites of the enzyme. The maximum power density achieved was 60% higher than that of PAA-PVI-$[Os(dCl-bpy)_2Cl]^{+/2+}$. Furthermore, high current density and electrode stability were confirmed for this osmium polymer, which makes it a promising candidate for high-efficiency biofuel cells.

• Journal of the Korean Electrochemical Society
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• v.7 no.1
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• pp.44-48
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• 2004

The two-component type enzyme amplified amperometric DNA assay is described to use an ambient $O_2$ of the substrate of the DNA labeling enzyme. Although the assay detects DNA only at > 0.5M concentration, a concentration $\~10^6$ fold higher than the sandwich-type enzyme amplified amperometric DNA assay, it can be run with an always available substrate. The assay utilizes screen-printed carbon electrodes (SPEs) which were pre-coated by a co-electrodeposited film of an electron conducting redox hydrogel and a 37-base long single-stranded DNA sequence. The DNA in the electron conducting film hybridizes and captures, when present, the 37-base long detection-DNA, which is labeled with bilirubin oxidase (BOD), an enzyme catalyzing the four-electron reduction of $O_2$ to water. Because the redox hydrogel electrically connects the BOD reaction centers to the electrode, completion of the sandwich converts the film from non-electrocatalytic to electrocatalytic for the reduction of $O_2$ to water when the electrode is poised at 200 mV vs. Ag/hgCl. The advantage or the assay over the earlier reported sandwich type enzyme amplified amperometric DNA assay, in which the amplifying enzyme was horseradish peroxidase, is that it utilizes ambient $O_2$ instead of the less stable and naturally unavailable $H_2O_2$.

• Journal of Life Science
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• v.12 no.3
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• pp.332-339
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• 2002

The pathogenesis of cholestatic liver injury as well as the modulation of hepatic fibrogenesis is causally associated with involvement of reactive oxygen species and free radical reactions. In this study, we investigated whether flavonoids (fustin, sulfuretin) which were isolated from Rhus verniciflua Stokes (RCS) have antioxidant and antihepatotoxicity effect under the biliary liver fibrosis condition. After surgery (control) and posttreated RCS methanol extract (250mg/kg), ethyl acetate extract (250mg/kg) and flavonoids were administered p.o. 10mg/kg/day in two weeks for control groups. The concentration of clinical parameters and product of hepatic lipid peroxidation and the hydroxyproline content were significantly increased in liver fibrosis developed rats. Among the clinical parameters of serum, value of ALT, AST, SDH, total bilirubin and ${\gamma}$ -GT in posttreated RCS components-group showed significantly lower than in control-group. The content of hydroxyproline in posttreated RCS components-group showed lower than in control group and then the value of MDA in posttreated RCS components-group was also significantly reduced to 40~60% of that in control group. The hepatic xanthine oxidase and aldehyde oxidate activities were posttreated RCS components-group showed significantly lower than in control-group. The hepatic SOD and glutathione peroxidase activities were posttreated RCS components-group showed significantly higher than in control-group. Hence we concluded that active components of fustin and sulfuretin which were isolated from R. verniciflua Stokes were hepatoprotective effect in experimental liver fibrosis.

• The Journal of Internal Korean Medicine
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• v.44 no.3
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• pp.402-417
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• 2023

Objective: Liver fibrosis is a highly conserved wound-healing response and the final common pathway of chronic inflammatory injury. This study aimed to evaluate the potential anti-fibrotic effect of the combination of Rhei Radix et Rhizoma water extract (RW) and silymarin in a thioacetamide (TAA)-induced liver fibrosis model. Methods: The liver fibrosis mouse model was established through the intraperitoneal injection of TAA (1 week 100 mg/kg, 2-3 weeks 200 mg/kg, 4-8 weeks 400 mg/kg) three times per week for eight weeks. Animal experiments were conducted in five groups; Normal, Control (TAA-induced liver fibrosis mice), Sily (silymarin 50 mg/kg), RSL (RW 50 mg/kg+silymarin 50 mg/kg), and RSH (RW 100 mg/kg+silymarin 50 mg/kg). Biochemical analyses were measured in serum, including aspartate aminotransferase (AST), alanine aminotransferase (ALT), malondialdehyde (MDA), and ammonia levels. Liver inflammatory cytokines and fibrous biomarkers were measured by Western blot analysis, and liver histopathology was evaluated through tissue staining. Results: A significant decrease in the liver function markers AST and ALT and a reduction in ammonia and total bilirubin were observed in the group treated with RSL and RSH. Measurement of reactive oxygen species and MDA revealed a significant decrease in the RSL and RSH administration group compared to the TAA induction group. The expression of extracellular matrix-related proteins, such as transforming growth factor β1, α-smooth muscle actin, and collagen type I alpha 1, was likewise significantly decreased. All drug-administered groups had increased matrix metalloproteinase-9 but a decreasing tissue inhibitor of matrix metalloproteinase-1. RSL and RSH exerted a significant upregulation of NADPH oxidase 2, p22^phox, and p47^phox, which are oxidative stress-related factors. Furthermore, pro-inflammatory proteins such as cyclooxygenase 2 and interleukin-1β were markedly suppressed through the inhibition of nuclear factor kappa B activation. Conclusions: The administration of RW and silymarin suppressed the NADPH oxidase factor protein level and showed a tendency to reduce inflammation-related enzymes. These results suggest that the combined administration of RW and silymarin improves acute liver injury induced by TAA.