• Journal of Applied Biological Chemistry
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• v.42 no.3
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• pp.130-133
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• 1999

Lipoxygenase activities of three cultivars of black rice (Chindo, Suwon-415, Yongkeum-1) were determined using an oxygen polargraphic method to measure oxygen uptake. Studies at different pH levels revealed that the optimum pH was about pH 7.0 for Suwon-415 and pH 7.5 for Chindo and Yongkeum-1. The specific activities of Chindo, Suwon-415 and Yongkeum-1 at optimal pH were 41.0, 27.3, and 29.6 unit/mg-protein, respectively. In all the cultivars, there was an increase in the activity with increase in reaction temperature. Enzyme activity was tested at different concentrations of the substrate. The resulting $K_m$ and $V_{max}$ values of Chindo, Suwon-415, and Youngkeum-1 were 0.059, 0.050, and 0.066 mM and 2020, 2283, and 1616 unit/g-grain, respectively. Enzyme activity decreased at all storage temperatures(25, 4, and $-40^{\circ}C$).

• Journal of the Korean Chemical Society
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• v.9 no.2
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• pp.71-74
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• 1965

Reduction of Ti(Ⅳ)-oxalate complex on dropping mercury electrode has been studied as a function of oxalate concentration and of pH varied with HCl. Assuming there are equilibrium $TiO(C_2O_4)_2= \;+\;2H^+\;=\;Ti^{+4}\;+\;2C_2O_4\;=\;+\;H_2O,\;K_4$ in addition to $TiO(C_2O_4)_2\;^=\;=\;TiO^{++}\;+\;2C_2O_4=\;K_2\;Ti(C_2O_4)_2\;^-\;=\;Ti^{+3}\;+\;2C_2O_4=\;K_3$ in the system cathodic wave has been well explained for that pH is higher than 0.5. The equilibrium constants $K_2,\;K_3$ and $K_4$ have been to be $2{\times}10^{-12},\;5{\times}10^{-13}$ and $10^{-11}$, respectively. The reduction of Ti(Ⅳ)-oxalate system is $Ti^{+4}\;+\;e\;{\to}\;Ti^{+3}$ in the concentration of hydrochloric acid, higher than 3M.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.197-201
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• 2001

Measuring of the dissolved oxygen is widely used for the environmental control of natural waters, sewage waste treatment, medical and biochemical studies, soil husbandry, food and drug process control, and prevention of corrosion in boilers. Especially, a power plants need special management for preventing accidents from corrosion, therefore, it is essential to measure the concentration of dissolved oxygen in real-time. In this paper we present a method of measuring dissolved oxygen very accurately up to ppb units. This method, called polarographic method, is based on the measures of the electric current generated by the oxidation process in cathode and de-oxidation process in anode, assuming that the amount of the current is proportional to the density of dissolved oxygen.

• YAKHAK HOEJI
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• v.16 no.2
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• pp.73-84
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• 1972

단백질과 전이금속 이온들과의 상호작용을 연구하는데 있어서 단백질중의 이미다졸기 및 아미노산의 반응성은 중요하다. Cd(II)-2-메틸이미다졸 착물들의 경우 이미다졸 분자중의 결합측은 "피로올"형 보다 오히려 "피리딘" 질소임을 알 수 있다. 이 착물들의 환원파는 가역적이며 2전자반응으로 나타난다. 그리고 이미다졸 존재하의 Ni(II) 이온은 촉매파를 나타내며 Ni(II) 이온만의 환원파는 불가역성인 것에 비해 가역성을 보여주었다. 또한 그 반파전위는 Ni(II) 이온만의 반파전위보다 수백 mV 양전위로 이동된다. 이러한 성질은 전극 반응에 관여한 주물질이 전극 표면에서 흡착되어 환원되기 때문이다. 이미다졸 농도의 대수값에 대해 반파전위를 도시했을 때 그 기울기가 30mV로써 이론치와 일치한다. 한편 $Cd(II)-2CH_{3}Im$의 단계적 생성항수 $pK_{1},pK_{2},pK_{3},pK_{4}$는 각각 2.68, 4.01, 4.90, 5.36이었다.4.01, 4.90, 5.36이었다.

• Bulletin of the Korean Chemical Society
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• v.11 no.2
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• pp.89-94
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• 1990

The redox properties of 2-amino-1-cyclopentene-1-dithiocarboxylate anion (acdc) and its oxovanadium complex, $VO(acdc)_2$ have been investigated in dimethylformamide (DMF) with polarography and cyclic voltammetry. Bis(2-amino-1-cyclopentene-1-dithiocarboxylate) oxovanadium(IV) exhibits two polarographic oxidation waves and two reduction waves in the potential range from +0.50V to - 2.4V vs. the Ag/AgCl (DMF) reference electrode. The second oxidation wave appeared at - 0.08V is found to be reversible and is attributed to the formation of $VO(acdc)_2\;^+$. The first reduction process (at - 0.60V) is also reversible and this reduction process is caused by the electrode process of formation of $VO(acdc)_2$-species. The half wave potential for the reduction, V(IV)$\to$V(III) is more positive for oxovanadium complexes containing sulfur donor atoms than other VO(IV) complexes having oxygen or nitrogen donor atoms.

• Bulletin of the Korean Chemical Society
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• v.11 no.1
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• pp.65-69
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• 1990

The nucleophilic substitution reactions of naphthalene-1,5-disulfonyl chloride and 4-fluorosulfonylbenzenesulfonyl chloride with p-substituted anilines and methyl substituted pyridines in methanol-acetonitrile mixtures and hydrolyses of those disulfonyl halides have been studied by means of conductometric and polarographic methods. A large difference in the selective parameter, ${\rho}_N$ between mono-sulfonyl chloride and disulfonyl halide can be taken as an evidence that the second $SO_2Cl$ grolup of naphthalene-1,5-disulfonyl chloride also takes part in the reaction in contrast to sulfonyl fluoride in 4-fluorosulfonylbenzenesulfonyl chloride, which only acts as a substituent in the nucleophilic substitution reaction.

• Archives of Pharmacal Research
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• v.23 no.3
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• pp.197-201
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• 2000

In an aqueous piperacillin sodium solution, a well-defined single wave or single peak was observed by direct current(DC) polarography or differential pulse polarography(DPP). The peak potential change per pH unit was -54 mV in the phosphate buffer at $18^{\circ}C$, which indicated that protons were involved in the electrochemical reduction of the 2,3-dioxopiperazine moiety of piperacillin sodium with a $H^{+}e^{-}$ ratio of one. Using a phosphate buffer of pH 4.3, the $1.0{times}10^{-7}$ M piperacillin sodium single peak could be determined by DPP with relative standard deviation of 1.6 %(n=3). Piperacillin sodium could be analyzed with-out interference from penicillin G-potassium, which enabled the employment of DPP as a fast and simple technique for monitoring the synthetic process of the antibiotic.

• Bulletin of the Korean Chemical Society
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• v.5 no.5
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• pp.182-187
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• 1984

The polarographic and conductometric studies of methyl viologen $(MV^{++})$ solutions with varying concentration of sodium dodecyl sulfate (SDS) showed strong association of $MV^{++}$ and its cationic radical, $MV^+$., with SDS below the critical micelle concentration. The stoichiometries of these associations were found to be their electric charge ratios. Both electrostatic and hydrophobic interactions were found to contribute to the associations. The formation constant of$MV^+.DS^-$ in 0.1 M NaCl was $7{\times}10^3M$. The $MV^{++}$-SDS association was observed to be cooperative leading to formation of large aggregates. In the presence of $MV^{++}$, the micellization of SDS was formation of SDS homo-micelle without direct involvement of $MV^{++}$.

• Bulletin of the Korean Chemical Society
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• v.12 no.3
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• pp.276-281
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• 1991

Electrochemical behaviors of optically active sparteine-Cu(II) dihalide complexes were investigated by polarography and cyclic voltammetry (CV). These Cu(II) complexes are rather easier to be reduced to Cu(I) states when comparison is made with other nonplaner copper complexes, We have assigned the CV peaks and polarographic waves related to the redox processes for these complexes. We could also observe the exchange reaction of Cu(II) ion in the complex with mercury metal in the cell having mercury pool. The redox mechanism of these complelxes is as follows; The 1st wave appeared at +0.47 V/+0.65 V corresponds to the reaction of $SpCuX_2+ e{\rightleftarrow}SpCuX_{2^-}$ and the 2nd one at +0.26 V/+0.21 V does the reaction of $SpCuX_{2 ^-} +e{\rightleftarrow}SpCuX_2^{2-}$. The 3rd one at -0.35 V/-0.27 V is dueto the reduction of mercury complex formed via exchange reaction. Where, X is chloride ion.

• Food Science and Biotechnology
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• v.17 no.1
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• pp.1-7
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• 2008

Soybeans with brown, black, and yellow seed coats were compared to total phenolic contents and antioxidant activities including 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radicals. Also, 3 seed coats were examined for inhibitory activities on tyrosinase and lipoxygenase-1 on the basis of spectrophotometric and polarographic methods. Among seed coat extracts, 80% methanol extract of brown soybean seed coat showed the highest total phenolic contents ($68.9{\pm}3.29\;mg$ GAE/g) as well as exhibited potent scavenging effects on the DPPH ($IC_{50}=4.3\;{\mu}g/mL$) and ABTS ($IC_{50}=3.7\;{\mu}g/mL$) radicals. In a polarographic experiment, this extract was potentially inhibited the oxidation of L-tyrosine and L-3,4-dihydroxy-phenylalanin (L-DOPA) catalyzed by mushroom tyrosinase with $IC_{50}$ values of 12.4 and $63.7\;{\mu}g/mL$, respectively. It was also detected inhibition of the tyrosinase catalyzed oxidation of L-DOPA with an $IC_{50}$ value of 120.3 mg/mL in UV spectrophotometric experiment. In addition, this extract inhibited the linoleic acid peroxidation catalyzed by lipoxygenase-1 with an $IC_{50}$ value of $4.0\;{\mu}g/mL$. These results suggest that brown soybean may possess more beneficial effect on human health than black and yellow soybeans.