• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.75-75
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• 1995

Succinic semialdehyde reductase, one of key enzyme of GABA shunt in CNS, is inactivated by o-phthalaldehyde, The inactivation followed pseudo first-order kinetics, and the second-order rate constant for the inactivation process was 28 M$\^$-1/s$\^$-1/ at pH 7.4 and 25$^{\circ}C$. The absorption spectrum(λ$\_$max/=377nm), fluorescence exitation(λ$\_$max/=340nm) and fluorescence emission spectra (λ$\_$max/=409nm) were consistent with the formation of an isoindole derivative in the catalytic site between a cysteine and a lysine residues about 3${\AA}$ apart. The substrate, succinic semialdehyde, did not protect the enzymatic activity against inactivation, whereas the coenzyme, NADPH, protected against o-phthalaldehyde induced inactivation of the enzyme. About 1 isoindole group per moi of the enzyme was formed following complete loss of the enzymatic activity. These results suggest that the amino acid residues of the enzyme participating in reaction with o-phthalaldehyde more likely residues at or near the coenzyme binding site.

• Archives of Pharmacal Research
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• v.25 no.5
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• pp.643-646
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• 2002

The succinic semialdehyde dehydrogenase (SSADH) inhibitory component was isolated from the EtOAc fraction of Lactuca sativa through repeated column chromatography; then, it was identified as phytol, a diterpenoid, based on the interpretation of several spectral data. Incubation of SSADH with the phytol results in a time-dependent loss of enzymatic activity, suggesting that enzyme modification is irreversible. The inactivation followed pseudo-first-order kinetics with the second-rate order constant of $6.15{\times}10^{-2}mM^{-1}min^{-1}.$ Complete protection from inactivation was afforded by the coenzyme $NAD^{+}$, whereas substrate succinic semialdehyde failed to prevent the inactivation of the enzyme; therefore, it seems likely that phytol covalently binds at or near the active site of the enzyme. It is postulated that the phytol is able to elevate the neurotransmitter GABA levels in central nervous system through its inhibitory action on one of the GABA degradative enzymes, SSADH.

• Journal of the Korean Chemical Society
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• v.36 no.4
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• pp.517-522
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• 1992

The reaction of ${\beta}$-picoline with substituted benzoyl chlorides has been studied by means of conductometry under various pressures in acetonitrile. From the values of pseudo-first order and second order rate constants, the activation parameters (${\Delta}V{\neq}$, ${\Delta}{\beta}{\neq}$, ${\Delta}H{\neq}$, ${\Delta}S{\neq}$ and ${\Delta}G{\neq}$) and the pressure dependence of Hammett ${\rho}$ value were studied. The activation volume, the activation compressibility coefficient and the activation entropy were all negative. By increasing pressure the rate constant and Hammett ${\rho}$ value were increased, and the reaction mechanism was proceed in bond formation favored.

• Animal cells and systems
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• v.1 no.4
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• pp.583-587
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• 1997

Incubation of an NADPH-dependent succinic semialdehyde reductase from bovine brain with N-bromosuccinimide (NBS) resulted in a time-dependent loss of enzyme activity. The inactivation followed pseudo-first-order kinetics with the second-order rate constant of $6.8\times{10}^3$ $M^-1$ $min^{-1}$. The inactivation was prevented by preincubation of the enzyme with substrate succinic semialdehyde, but not with coenzyme NADPH. There was a linear relation-ship between oxindole formation and the loss of enzyme activity. Spectro-photometric studies indicated that about one oxindole group per molecule of the enzyme was formed following complete loss of enzymatic activity. It is suggested that the catalytic function of succinic semialdehyde reductase is modulated by binding of NBS to a specific tryptophan residue at or near the substrate binding site of the enzyme.

• Bulletin of the Korean Chemical Society
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• v.10 no.1
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• pp.72-74
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• 1989

Aminolysis of various carboxyl-containing ester substrates by triamines was kinetically studied in dimethyl sulfoxide (DMSO) in the presence of p-toluenesulfonic acid (TSA) or in the presence of sulfuric acid and potassium iodide (KI). In the presence of TSA or KI, the pseudo-first-order rate constants ($k_o$) were proportional to the total amine concentration ($N_o$). This stands in marked contrast with the corresponding reactions carried out with sulfuric acid added as the sole additive, in which saturation kinetic behavior of ko with respect to No was manifested. This indicates that complex formation between the ester substrate and the amine is greatly suppressed by the addition of TSA or KI. The second-order rate constants obtained in the presence of TSA or KI were substantially greater than those measured in the absence of any additive. These kinetic features were explained in terms of tight interaction between the protonated amines with I- or TSA-. Thus, the results were related to the hydrogen bonding that involves DMSO, bisulfate ion, I-, TSA-, and the protonated forms of triamines.

• Bulletin of the Korean Chemical Society
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• v.22 no.7
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• pp.673-677
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• 2001

Pseudo-first-order rate constants have been measured spectrophotometrically for the reactions of 8-(5-nitroquinolyl) 3-furoate with alkali metal ethoxides in anhydrous ethanol. The plot of kobs vs the concentration of alkali metal ethox ides is linear for the reactions performed in the presence of a complexing agent, 18-crown-6 ether, but exhibits upward curvatures for the corresponding reactions performed in the absence of the complexing agent, indicating that the alkali metal ions in this study behave as catalysts. Second-order rate constants were determined for the reactions with dissociated free ethoxide (kEtO-) and with ion paired alkali metal ethoxides (kEtO-M + ) from ion pairing treatments. The magnitude of catalytic effect (kEtO-M + /kEtO-) was found to be 1.7, 3.4 and 2.5 for the reaction of 8-(5-nitroquinolyl) 3-furoate, while 1.4, 3.6 and 4.2 for that of 4-nitrophenyl 2-furoate, 1.8, 3.7 and 2.4 for that of 8-(5-nitroquinolyl) benzoate, and 2.0, 9.8 and 9.3 for that of 8-(5-nitroquinolyl) 2-furoate with EtO- Li+ , EtO- Na+ and EtO- K+ , respectively. A 5-membered chelation at the leaving group is suggested to be responsible for the catalytic effect shown by alkali metal ions.

• Membrane and Water Treatment
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• v.8 no.2
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• pp.161-169
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• 2017

The adsorption of phosphate onto mesoporous $TiO_2$ was investigated in order to reduce phosphorus concentrations in wastewater and provide a potential mode of phosphorus recovery. Three equilibrium isotherms were used to optimize and properly describe phosphate adsorption ($R^2$>0.95). The maximum capacity of phosphate on the adsorbent was found to be 50.4 mg/g, which indicated that mesoporous $TiO_2$ could be an alternative to mesoporous $ZrO_2$ as an adsorbent. A pseudo-second order model was appropriately fitted with experimental data ($R^2$>0.93). Furthermore, the suitable pH for phosphate removal by $TiO_2$ was observed to be in the range of pH 3-7 in accordance with ion dissociation. In contrast, increasing the pH to produce more basic conditions noticeably disturbed the adsorption process. Moreover, the kinetics of the conducted temperature study revealed that phosphate adsorption onto the $TiO_2$ adsorbent is an exothermic process that could have spontaneously occurred and resulted in a higher randomness of the system. In this study, the maximum adsorption using real wastewater was observed at $30^{\circ}C$.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.456-461
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• 2022

Heavy metal pollution is caused due to anthropogenic activities and is considered as a serious environmental problem which endangers human health and environment. The present study deals with biosorption, an eco-friendly technique for the removal of heavy metal Zn(II) from aqueous medium. Various natural materials have been explored for the uptake of metal ions, where most of them are physically or chemically enhanced. Dry cowdung powder (DCP) has been utilized as a low-cost, environmentally friendly humiresin without any pre-treatment, thus demonstrating the concept of Green Chemistry. Batch biosorption studies using ⁶⁵Zn(II) tracer were performed and the impact of different experimental parameters was studied. Results revealed that at pH 6, 94 ± 2% of Zn(II) was effectively biosorbed in 5 min, at 303 K. The process was spontaneous and exothermic, following pseudo-second-order reaction. The mechanism of heavy metal biosorption employing green adsorbent was therefore elucidated in order to determine the optimal method for removing Zn(II) ions. DCP has a lot of potential in the wastewater treatment industry, as seen by its ability to meet 3A's affordability, adaptability, and acceptability criteria. As a result, DCP emerges as one of the most promising challengers for green chemistry and the zero-waste idea.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1114-1122
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• 2005

This research investigates the effects of sonication mode, reaction temperature and volume on sonolysis of 1,4-dioxane in order to increase the degradation efficiency and kinetics. The degradation efficiency in case with pulse mode was about 10 % higher than that in case with continuous mode. The degradation profiles in both cases, which were performed without the control of reaction temperature and in 1000 mL, were composed of three steps. However, 1,4-D was mainly degraded in the initiation step as the first portion and the acceleration step as the second portion. The initial step agreed with zero-order expression well, while the acceleration step could be fitted with pseudo 1st-order expression. The kinetic model in case with $5^{\circ}C$ and 300 mL conformed to pseudo 1st-order, while that in cases with $10^{\circ}C$ to $40^{\circ}C$ agreed with zero-order expression. The degradation efficiency and profile of 1,4-D in the experiment with $20^{\circ}C$ and 300 mL was higher and simpler than that in case with $20^{\circ}C$ and 1000 mL. The reaction temperature and volume influence bubble intensity, which was produced in sonication. The increase of bubble intensity induced to augment the production of OH radical in sonication.

• Resources Recycling
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• v.22 no.1
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• pp.55-63
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• 2013

Considering considerable contents of vanadium and tungsten in spent SCR DeNOx catalysts, separation and recovery of those metals are required. In this respect, commercial anion exchange resin (MP600) was employed to recover vanadium from the synthetic solution of ammonium metavanadate. Experimental results indicated that vanadium exist as anion under the acidic condition (pH 2 ~ 6) and adsorbed on the resin. Although the adsorption rate was increased with temperature, the maximum amount of adsorption was not affected by temperature. Desorption took place under either strong acidic (less than pH 1) or strong caustic (higher than pH 13) condition. However, desorption seldom took place under moderate conditions (pH 3~11). Furthermore, adsorption equilibrium results agreed well with Freundlich isotherm and pseudo-second-order reactions. And, adsorption energy was evaluated using Dubinin-Radushkevich and Temkin isotherm.