• Korean Journal of Crystallography
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• v.2 no.1
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• pp.12-16
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• 1991

C18H22N4OS, Mr=342.47, monoclinic, P2₁/c,a=11.802(2), b=31.962(2), c=9.829(2)A, β=100.12(1)˚, V=3694.8A3,F(000)=1472, Z=8, Dx=1.246 Mg m-3, Dm=1.17Mg m-3,λ=0.71073 A, μ=0.15mm-1, T=294 K. final R=0.0856 for 3718 observed reflection (Fo>3σ(Fo)) There are two molecules in an asymmetric unit and a major difference between these molecules is in the C(9)-N(1)-C(6)-C(7) torsion angles [58.8(8)˚and 1(1)˚]. Both molecules have intramolecular N(1)-H(10)'N(3) hydrogen bonds [ 2.613(7) and 2.566(7) A] and assume V-shaped conformation with N(2) atoms at the verices. The two independent molecules are linked by the two N(2)-H(11)'S' hydrogen bonds[3.367(5) A and 3.421(4)A] and the dimergen are held together by van der Waals forces.

• Applied Biological Chemistry
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• v.35 no.3
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• pp.170-172
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• 1992

Four types of polyphenol oxidase were isolated from the crude extract of a Ligularia fischeri by gel filtration on Sephadex G-150. Optimum pH and temperature for the activity of partially purified enzyme were 7.5 and $25^{\circ}C$, respectively. It was stable at temperature $40^{\circ}C$ when examined at pH 7.5 for 5 min, and lost 90% of its activity at $70^{\circ}C$ in 30 min at pH 7.5. The enzyme has good activity on catechol and chlorogenic acid but was inactive on dopamine.

• Microbiology and Biotechnology Letters
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• v.17 no.3
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• pp.198-201
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• 1989

Steptomyces sp. GI 32 with high production of glucose isomerase was isolated from soil. The maximum enzyme production was observed in the culture medium containing 1% sorbitol, 0.6% tryptone, 0.4% yeast extract, 1mM Fe$_2$(SO$_4$)$_3$ with initial pH 7.0 when the cell was cultured at 35$^{\circ}C$ about 18 hours with shaking. The enzyme was partially purified by ammonium sulfate fractionation and DEAE cellulose chromatography. The enzyme was also appeared to be relatively thermostable, and no apopreciable inactivation was observed after incubation at 7$0^{\circ}C$ for 1 hour. The optimal pH and temperature of the enzyme were pH 8.0 and 7$0^{\circ}C$, respectively.

• Microbiology and Biotechnology Letters
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• v.30 no.1
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• pp.26-32
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• 2002

For commercial production of Korean fermented anchovy sauce through rapid fermentation, a bacterial strain which showed the high protease activity was isolated from a commercially fermented anchovy sauce. The isolate was Bacillus amyloliquefaciens, and named as B. amyloliquefaciens HTP-8. The incubation temperature, initial pH, and cultivation time for optimal production of protease by B. amyloliquefaciens HTP-8 were $30^{\circ}C$, 7.0, and 3 days, respectively. In jar fermenter, B. amyloliquefaciens HTP-8 showed higher protease activity when grown at pH 7.0. The protease was partially purified by 80% ammonium sulfate precipitation and CM-Sephadex C-50 ion exchange chromatography. The partially purified enzyme had specific activity of 103.3 units/mg, yield of 0.4%, and purification fold of 43.0. The optimal pH and temperature for the protease activity were 10.0 and $50^{\circ}C$, respectively. The protease was relatively stable at the pH range of 7.0~12.0 and at the temperatures below 4$0^{\circ}C$. The activity of the enzyme was inhibited by $Ag^{＋}$ /, $Ba^{2＋}$ and selectively inhibited by PMSF, suggesting that it is a serine protease.

• Korean Journal of Crystallography
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• v.8 no.1
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• pp.59-63
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• 1997

A method for the calculation of the idealized hydrogen positions in the following seven different kinds of compounds has been shown: (1) tertiary C-H, (2) secondary C-H, (3) $CH_3$ group with tetrahedral angles, (4) aromatic C-H or amide N-H, (5) O-H group with X-O-H angle tetrahedral, (6) terminal $X=CH_2$ or $X=NH_2^+$ with the hydrogen atoms in a plane and (7) acetylenic C-H with X-C-H linear.

• Food Science of Animal Resources
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• v.32 no.1
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• pp.62-67
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• 2012

This study calculated kinetic parameters of Escherichia coli O157:H7 and developed a probabilistic model to estimate growth probabilities of E. coli O157:H7 on polyethylene cutting boards as a function of temperature and time. The surfaces of polyethylene coupons ($3{\times}5$ cm) were inoculated with E. coli O157:H7 NCCP11142 at 4 Log $CFU/cm^2$. The coupons were stored at 13 to $35^{\circ}C$ for 12 h, and cell counts of E. coli O157:H7 were enumerated on McConkey II with sorbitol agar every 2 h. Kinetic parameters (maximum specific growth rate, Log $CFU/cm^2/h$; lag phase duration, h; lower asymptote, Log $CFU/cm^2$; upper asymptote, Log $CFU/cm^2$) were calculated with the modified Gompertz model. Of 56 combinations (temperature${\times}$time), the combinations that had ${\geq}$0.5 Log $CFU/cm^2$ of bacterial growth were designated with the value of 1, and the combinations that had increases of <0.5 Log $CFU/cm^2$ were given the value 0. These growth response data were fitted to the logistic regression to develop the model predicting probabilities of E. coli O157:H7 growth. Specific growth rate and growth data showed that E. coli O157:H7 cells were grown at $28-35^{\circ}C$, but there were no obvious growth of the pathogen below $25^{\circ}C$. Moreover, the developed probabilistic model showed acceptable performance to calculate growth probability of E. coli O157:H7. Therefore, the results should be useful in determining upper limits of working temperature and time, inhibiting E. coli O157:H7 growth on polyethylene cutting board.

• Applied Chemistry for Engineering
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• v.28 no.5
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• pp.597-600
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• 2017

$(C_{10}H_8N_2H)_2Cr_2O_7$ was synthesized by reacting 4,4'-bipyridine and chromium (VI) trioxide. The structure of the product was characterized with FT-IR (infrared spectroscopy) and elemental analysis. The oxidation of benzyl alcohol using $(C_{10}H_8N_2H)_2Cr_2O_7$ in various solvents showed that the reactivity increased with the increase of the solvent dielectric constant, in the order of DMF (N,N'-dimethylformamide) > acetone > chloroform > cyclohexane. In the presence of DMF, an acidic catalyst such as $H_2SO_4$ $(C_{10}H_8N_2H)_2Cr_2O_7$ oxidized benzyl alcohol (H) and its derivatives ($p-OCH_3$, $m-CH_3$, $m-OCH_3$, m-Cl, $m-NO_2$). Electron donating substituents accelerated the reaction rate, whereas electron acceptor groups retarded the reaction rate. Hammett reaction constant (${\rho}$) was -0.70 (308 K). The observed experimental data were used to rationalize the hydride ion transfer in the rate determining step.

• Korean Journal of Food Science and Technology
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• v.21 no.3
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• pp.351-359
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• 1989

This study was conducted to observe the physico-chemical exchange and effect of amino-carbonyl reaction between fructose and glycine . When various buffer solutions were added to equimolar mixture of fructose and glycine at pH 6.0 and $100^{\circ}C$, the browning effect was markedly observed by Mcllvaine buffer. Among the combinations of temperature and reaction time, the deep browning effect was obtained above $100^{\circ}C$, 3hr A marked browning effect obtained above pH 7.0 but little observed below pH 7.0. The browning effect was markedly increased at high fructose concentration. It required 4.0hrs and 32.9hrs to decrease 50% of initial concentration of fructose and glycine at $100^{\circ}C$ and pH 7 but 0.9hrs and 3.8hrs at $120^{\circ}C$, pH 7.0, respectively. The rate constant of fructose and glycine at $100^{\circ}C\;and\;120^{\circ}C$ were $1.78{\times}10^{-1},\;2.11{\times}10^{-2}\;and\;7.74{\times}10^{-1},\;1.83{\times}10^{-1}$, respectively. The formation of HMF was likely to follow the first order kinetics. The addition of 0.1M sodium sulfite, 0.1M sodium bisulfite and 0.1M calcium chloride to equimolar mixture (0.05M) surpressed the reaction up to 76.8%, 76.8% and 96.4%, respectively.

• Korean Journal of Food Science and Technology
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• v.10 no.1
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• pp.36-45
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• 1978

Surface ultrastructural changes in endomysial connective tissue, sarcolemma and transverse ridges of bovine psoas muscle produced by leukocyte lysosomal enzymes in vitro at different pH (pH 7.0 and 4.0), temperature (37 and $4^{\circ}C$) and time interval (12, 24 hours at $37^{\circ}C$ and 36, 168 hours at $4^{\circ}C$ were studied by scanning electron microscope. Muscle incubated with leukocyte lysosomal enzymes at pH 7.0 produced severe degradation of endomysial and sarcolemmal connective tissue and transverse ridges but at pH 4.0 endomysial and sarcolemmal structures remain moderately stable and tranverse ridges are very stable even after 24 hours incubation at $37^{\circ}C$ and 7 days incubation at $4^{\circ}C$.

• Korean journal of food and cookery science
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• v.9 no.1
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• pp.43-51
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• 1993

Buckwheat protein isolate was tested for the effects of pH, addition of sodium chloride and heat treatment on solubility, emulsion capacities, emulsion stability, surface hydrophobicity, foam capacities and foam stability. The solubility of buckwheat protein isolate was affected by pH and showed the lowest value at pH 4.5, the isoelectric point of buckwheat protein isolate. The solubility significantly as the pH value reached closer to either ends of the pH, i.e., pH 1.0 and 11.0. The effects of NaCl concentration on solubility were as follows; at pH 2.0, the solubility significantly decreased when NaCl was added; at pH 4.5, it increased above 0.6 M; at pH 7.0 it increased; and at pH 9.0 it decreased. The solubility increased above $80^{\circ}C$, at all pH ranges. The emulsion capacity was the lowest at pH 4.5. It significantly increased as the pH approached higher acidic or alkalic regions. At pH 2.0, when NaCl was added, the emulsion capacity decreased, but it increased at pH 4.5 and showed the maximum value at pH 7.0 and 9.0 with 0.6 M and 0.8 M NaCl concentrations. Upon heating, the emulsion capacity decreased at acidic pH's but was maximised at pH 7.0 and 9.0 on $60^{\circ}C$ heat treatment. The emulsion stability was the lowest at pH 4.5 but increased with heat treatment. At acidic pH, the emulsion stability increased with the increase in NaCl concentration but decreased at pH 7.0 and 9.0. Generally, at other pH ranges, the emulsion stability was decreased with increased heating temperature. The surface hydrophobicity showed the highest value at pH 2.0 and the lowest value at pH 11.0. As NaCl concentrationed, the surface hydrophobicity decreased at acidic pH. The NaCl concentration had no significant effects on surface hydrophobicity at pH 7.0, 9.0 except for the highest value observed at 0.8 M and 0.4 M. At all pH ranges, the surface hydrophobicity was increased, when the temperature increased. The foam capacity decreased, with increased in pH value. At acidic pH, the foam capacity was decreased with the increased in NaCl concentration. The highest value was observed upon adding 0.2 M or 0.4 M NaCl at pH 7.0 and 9.0. Heat treatments of $60^{\circ}C$ and $40^{\circ}C$ showed the highest foam capacity values at pH 2.0 and 4.5, respectively. At pH 7.0 and 9.0, the foam capacity decreased with the increased in temperature. The foam stability was not significantly related to different pH values. The addition of 0.4 M NaCl at pH 2.0, 7.0 and 9.0 showed the highest stability and the addition of 1.0 M at pH 4.5 showed the lowest. The higher the heating temperature, the lower the foam stability at pH 2.0 and 9.0. However, the foam stability increased at pH 4.5 and 7.0 before reaching $80^{\circ}C$.