• Journal of Microbiology and Biotechnology
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• v.20 no.7
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• pp.1077-1085
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• 2010

With an emphasis on its thermal behavior with different pHs and salts, the kinetic and thermodynamic parameters of the purified polygalacturonase (PG) from E. carotovora subsp. carotovora (Ecc) BR1 were studied, as the characterization of an enzyme is significant in the context of burgeoning biotechnological applications. The thermodynamic parameters for polygalacturonic acid hydrolysis by the purified PG were ${\Delta}H^*$=7.98 kJ/mol, ${\Delta}G^*$=68.86 kJ/mol, ${\Delta}S^*$=-194.48 J/mol/K, ${\Delta}G_{E-S}$=-1.04 kJ/mol, and ${\Delta}G_{E-T}$=-8.96 kJ/mol. In addition, its turnover number ($k_{cat}$) was 21/sec. The purified PG was stable within a temperature range of $20-50^{\circ}C$ and was deactivated at $60^{\circ}C$ and $70^{\circ}C$. The thermodynamic parameters (${\Delta}H^*$, ${\Delta}G^*$, ${\Delta}S^*$) for the irreversible inactivation of the PG at different temperatures ($30-60^{\circ}C$) were determined, where the effectiveness of various salts and different pHs (4-8) for the thermal stability of the PG were also characterized. The efficacy of various salts for the thermal stability of the PG was in the following order: $MgCl_2$ > $BaCl_2$ > KCl > $CaCl_2$ >NaCl. Therefore, the present work presents the biochemical, substrate hydrolysis thermodynamics and the thermal stabilization parameters of the PG from Ecc.

• Bulletin of the Korean Chemical Society
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• v.20 no.8
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• pp.948-952
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• 1999

Electrophilic substitutions on β-position of 2,5-dimethyl pyrrole have been investigated theoretically. The electron donating methyl groups enrich electron densities on C-3, C-4 positions and π* interactions with methyl groups substituted on C-2 and C-5 positions pushed up the HOMO level of the pyrroles consequently induce rapid substitutions on C-3, C-4 sites. Substitution of phenylsulfonyl group on nitrogen stabilized LUMO levels through weak π bonding interactions. Unexpected deoxidation reaction underwent on the sulfonyl group substituted at C-3 position. The structures were solved by X-ray crystallography. Meanwhile, gas phase HF/6-31G* and density functional method (B3LYP/6-31G*) calculations gave favorable energies for 1-phenylsulfinyl pyrrole (6) over 3-phenylsulfinyl pyrrole (5) by 3.6-4.7 kcal/mol which is contrary to the experimental result. However the methods involve the effects of molecular polarizability and solvent, molecular dynamics (MD) and ab-initio self consistent reaction field (SCRF) calculations showed same trend as experiments. According to MD calculations, compound 5 is more stable than compound 6 by 4.15 kcal/mol and the SCRF, HF/6-31G* calculations gave more stable energy value for structure 5 than 6 by 0.03 kcal/mol.

• Journal of Microbiology and Biotechnology
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• v.25 no.4
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• pp.452-458
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• 2015

The biocatalytic efficiency of recombinant Corynebacterium glutamicum ATCC 13032 expressing the secondary alcohol dehydrogenase of Micrococcus luteus NCTC2665 was studied. Recombinant C. glutamicum converts ricinoleic acid to a product, identified by gas chromatography/mass spectrometry as 12-ketooleic acid (12-oxo-cis-9-octadecenoic acid). The effects of pH, reaction temperature, and non-ionic detergent on recombinant C. glutamiucm whole cell bioconversion were examined. The determined optimal conditions for production of 12-ketooleic acid are pH 8.0, 35℃, and 0.05 g/l Tween80. Under these conditions, recombinant C. glutamicum produces 3.3 mM 12-ketooleic acid, with a 72% (mol/mol) maximum conversion yield, and 1.1 g/l/h volumetric productivity in 2 h; and 3.9 mM 12-ketooleic acid, with a 74% (mol/mol) maximum conversion yield, and 0.69 g/l/h maximum volumetric productivity in 4 h of fermentation. This study constitutes the first report of significant production of 12-ketooleic acid using a recombinant Corynebacterium glutamicum-based biocatalyst.

• Resources Recycling
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• v.17 no.3
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• pp.48-55
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• 2008

Leaching of copper and silver from mobile phone PCBs(printed circuit boards) with nitric acid was performed to investigate the effects of nitric acid concentrations, leaching temperatures, agitation speeds, and pulp densities on the leaching behaviors of Cu and Ag. The leaching rate considerably increased with increasing acid concentration and temperature. The leaching ratios of Cu and Ag were found to be 96.4% and 96.5%, respectively, under the optimum condition; at $80^{\circ}C$ with 2mol/L $HNO_3$ and 120g/L in pulp density within 39minutes. The kinetic parameters were determined based on the shrinking core model with reaction control corresponding to small particles. The activation energies for the leaching of copper and silver were found to be 45.5kJ/mol and 60.5kJ/mol at $35{\sim}80^{\circ}C$ with 2mol/L $HNO_3$, respectively.

• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.559-566
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• 1999

Gas-phase alkylations of delocalized ambident anions, Y---CH---X- where X, Y=CH2, O, or S, have been investigated theoretically at the MP2/6-31+G*//MP2/6-31+G* and QCISD/6-31+G*//MP2/6-31+G* lev-els. O-and S-alkylations (X=O and S) are more favored kinetically by ΔE^≠ = 4.6 and 9.8 kcal mol-1 than the respective C-alkylations even though they are thermodynamically less favored by 22.4 and 6.0 kcal mol-1 respectively. It was found that the transition structures for the C-alkylations are imbalanced due to the endoergic rehybridi-zation of the carbon center from sp2 to sp3 which leads to premature bond contraction of the C-Y bond and delayed bond stretching of the C-X bond. In the O-, or S-alkylation, such endoergic process is not required since the σ-lone pair on O or S is involved in the initial stage of alkylation. The imbalanced TSs for the C-alkylation are accompanied by higher intrinsic barriers and deformation energies.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.3
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• pp.177-182
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• 1986

The dynamic mechanical properties of milk gel were examined as function of temperature, concentrations of milk and enzyme. The real and imaginary parts of the complex rigdity G' and G' were measured at $2\%$ strain and 5 rad/s of frequency. The results showed that the rigidity of milk gel was dependent on the concentration of milk (C) in such a way that $\sqrt{G'}{\propto}C$. It was found that gel point ($t_g$) was dependent on the concentration of milk as $t_g{\propto}C$, and on the concentration of enzyme as $t_g{\propto}\;1/(E)$, The activation energy of enzymatic reaction stage and coagulation stage were $21.1{\pm}5.8\;kcal/mol$ and $26.4{\pm}1.14\;kcal/mol$, respectively.

• Polymer(Korea)
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• v.27 no.1
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• pp.26-32
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• 2003

Poly(vinyl pivalate)(PVPi) telomer containing bifunctional end groups was synthesized through radical telomerization of vinyl pivalate. The number-average molecular weight ($\bar{M}$n) of the synthesized telomers was investigated by GPC, $^1$H-NMR, and viscometric methods. PVPi telomers having a number-average molecular weight ($\bar{M}$n) of 2400~1300 g/mol were obtained. In order to control the molecular weight of telomers, chain transfer constants ($C_s$) of telogen ($CCl_4$) were determined by using the Mayo equation and simulation, which were 1.15, 1.16, and 1.18 at 40, 50, and 6$0^{\circ}C$, respectively. $\bar{M}$n of the synthesized telomers at 6$0^{\circ}C$ were between 5100 and 5400 g/mol at conversion of increasing from 18 to 72%. Those are corresponding to simulation results.

• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.312-319
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• 2021

This study was conducted to investigate the effect of elevated carbon dioxide on the growth and physiological responses of peach 'Mihong' (Prunus persica). We simulated three different carbon dioxide conditions based on climate change scenarios RCP 8.5 in the sunlight phytotron rooms from April 22 to July 6, 2020; 400 µmol·mol^-1(present condition), 700 µmol·mol^-1 treatment(expecting carbon dioxide concentrations in mid-21st century), 940 µmol·mol^-1 treatment (expecting carbon dioxide concentrations in late 21st century). The average of maximum photosynthesis rate at 700 µmol·mol^-1(16.06 µmol·CO₂·m^-2·s^-1) was higher than those at 400 µmol·mol^-1(14.45 µmol·CO₂·m^-2·s^-1) and 940 µmol·mol^-1(15.96 µmol·CO₂·m^-2·s^-1) from May 22 to July 2. However, stomatal conductances at 700 µmol·mol^-1 and 940 µmol·mol^-1 were lower than those at the control. Also, the carbon dioxide saturation point in all treatments was reduced from 1,200 µmol·mol^-1 in the early stage of growth to 600-800 µmol·mol^-1 in the late stage of growth. The stomatal densities were decreased as carbon dioxide increased. The shoot lengths were decreased while the carbon dioxide was increased, but the increase of trunk diameter and leaf areas, shoot numbers were not statistically different. The fruit weight at 700 µmol·mol^-1(152.5 g) was higher than those at the control(141.8 g) and 940 µmol·mol^-1(147.4 g). The soluble solids were higher at 700 µmol·mol^-1, 940 µmol·mol^-1 compared to the control. These results suggest that a carbon dioxide elevated to 700 µmol·mol^-1 in the future may give a positive effect on the yield and fruit quality of peach 'Mihong' while a carbon dioxide elevated above 940 µmol·mol^-1 may affect negatively such as early senescence and loss of fruit set.

• Journal of the Korean Ceramic Society
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• v.28 no.2
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• pp.109-118
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• 1991

Steady-state sublimation vapour pressures of anhydrous bismuth triiodide have been measured by the torsion-effusion method from 488.8 to 570.5 K and equilibrium sublimation pressures were obtained from the steady-state data. The standard sublimation enthalpy changes derived by both second(modified sigma function) and third(average enthalpy method) law methods were 159.316${\pm}$0.055, 137.67${\pm}$1.43 kJ$.$mol-1 respectively. The standard sublmation entropy change derived by modified sigma function was 232.88${\pm}$0.10 J$.$K-1$.$mol-1. The reliable standard sublimation enthalpy change based on a correlation of {{{{ { TRIANGLE }`_{cr } ^{g } }} H{{{{ { 0} atop {m } }}(298.15K) and {{{{ { TRIANGLE }`_{cr } ^{g } }} S{{{{ { 0} atop {m } }}(298.15K), a recommended p(T) equation has been obtained for BiI3(cr) ; lg(p/Pa)=-(C$.$K/T)+5.071lg(T/K)-2.838${\times}$10-3(T/K)-7.758${\times}$103(K/T)2+1.4519 where C={{{{{ { TRIANGLE }`_{cr } ^{g } }} H{{{{ { 0} atop {m } }}(298.15K)/0.019146 kJ$.$mol-1}-456.27.

• Textile Coloration and Finishing
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• v.8 no.2
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• pp.16-24
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• 1996

Polyester microfiber fabrics were alcoholysed at 120, 140, and 16$0^{\circ}C$ in 0.5, 1.0, and 1.5% of sodiumglycerolate/glycerol solutions(NaGR) up to 80% and the characteristic decomposition features were compared and discussed with the results of the hydrolysis done by 5% sodium hydroxide solution(NaOH) at 80, 90, and 10$0^{\circ}C$. The resulting activation thermodynamic parameters calculated by the combined use of the Arrhenius equation and the Eyring equation were in NaOH case ${\Delta}H^*$=- 13.89 kcal/mol, ${\Delta}S^*$/=-38.12 cal/mol K, and ${\Delta}G^*$=25.25 kcal/mol and in NaGR case ${\Delta}H^*$=29.81 kcal/mol, ${\Delta}S^*$=-2.29 cal/mol K and ${\Delta}G^*$=30.49 kcal/mol. Since in all cases NaGR-PET system has higher activation thermodynamic parameters, it was concluded that NaGR-PET reaction system is more favorable at high temperatures and occurs in a less selective fashion, in comparison to the NaOH-PET reaction system.