• BMB Reports
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• 제28권2호
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• pp.124-128
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• 1995

Biodegradative threonine dehydratase purified from Serratia marcescens ATCC 25419 was inactivated by the arginine specific modification reagent, phenylglyoxal (PGO) and the lysine modification reagent, pyridoxal 5'-phosphate (PLP). The inactivation by PGO was protected by L-threonine and L-serine. The second order rate constant for the inactivation of the enzyme by PGO was calculated to be 136 $M^{-1}min^{-1}$. The reaction order with respect to PGO was 0.83. The inactivation of the enzyme by PGO was reversed upon addition of excess hydroxylamine. The inactivation of the enzyme by PLP was protected by L-threonine, L-serine, and a-aminobutyrate. The second order rate constant for the inactivation of the enzyme by PLP was 157 $M^{-1}min^{-1}$ and the order of reaction with respect to PLP was 1.0. The inactivation of the enzyme by PLP was reversed upon addition of excess acetic anhydride. Other chemical modification reagents such as N-ethylmaleimide, 5,5'-dithiobis (2-nitrobenzoate), iodoacetamide, sodium azide, phenylmethyl sulfonylfluoride and diethylpyrocarbonate had no effect on the enzyme activity. These results suggest that essential arginine and lysine residues may be located at or near the active site.

• Journal of Microbiology and Biotechnology
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• 제11권5호
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• pp.838-844
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• 2001

The enzyme Fuc aldolase from Methanococcus jannaschii that catalyzes the aldol condensation of DHAP and L-lactaldehyde to give fuculose-1-phosphate was inactivated by DEP. The inactivation was pseudo first-order in the enzyme and DEP, which was biphasic. A pseudo second-order rate constant of 120$M^{-1}min^{-1}$ was obtained at pH 6.0 and $25{\circ}C$. Quantifying the increase in absorbance at 240nm showed that four histidine residues per subunit were modified during the nearly complete inactivation. The statistical analysis and the time course of the modification suggested that two or three histidine residues were essential for activity. The rate of inactivation was dependent on the pH, and the pH inactivation data implied the involvement of the amino acid residue with a $pK_a$ value of 5.7. Fuc aldolase was protected against DEP inactivation by DHAP, indicating that the histidine residues were located at the active site of Fuc aldolase. DL-Glyceraldehyde, as an alternative substrate to L-lactaldehyde, showed no specific protection for the Fuc aldolase.

• 한국환경과학회지
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• 제28권3호
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• pp.291-301
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• 2019

This study was conducted to investigate the effect of salt concentration and turbidity on the inactivation of Artemia sp. by electrolysis, UV photolysis, electrolysis+UV process to treat ballast water in the presence of brackish water or muddy water caused by rainfall. The inactivation at different salt concentrations (30 g/L and 3 g/L) and turbidity levels (0, 156, 779 NTU) was compared. A decrease in salt concentration reduced RNO (OH radical generation index) degradation and TRO (Total Residual Oxidant) production, indicating that a longer electrolysis time is required to achieve a 100% inactivation rate in electrolysis process. In the UV process, the higher turbidity results in lower UV transmittance and lower inactivation efficiency of Artemia sp. Higher the turbidity resulted in lower ultraviolet transmittance in the UV process and lower inactivation efficiency of Artemia sp. A UV exposure time of over 30 seconds was required for 100% inactivation. Factors affecting inactivation efficiency of Artemia sp. in low salt concentration are in the order: electrolysis+UV > electrolysis > UV process. In the case of electrolysis+UV process, TRO is lower than the electrolysis process, but RNO is more decomposed, indicating that the OH radical has a greater effect on the inactivation effect. In low salt concentrations and high turbidity conditions, factors affecting Artemia sp. inactivation were in the order electrolysis > electrolysis+UV > UV process. When the salt concentration is low and the turbidity is high, the electrolysis process is affected by the salt concentration and the UV process is affected by turbidity. Therefore, the synergy due to the combination of the electrolysis process and the UV process was small, and the inactivation was lower than that of the single electrolysis process only affected by the salt concentration.

• BMB Reports
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• 제30권2호
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• pp.113-118
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• 1997

Aspartase from Hafnia alvei was inactivated by N-ethylmaleimide (NEM) and 5,5' -Dithiobis-(2-znitrobenzoic acid) (DTNB) following pseudo-first order kinetics. Their apparent reaction orders were 0.83 and 0.50 for NEM and DTNB modifications, respectively, indicating that inactivation was due to a sulfhydryl group in the active site of aspartase and participation of the sulfhydryl group in an essential step in the catalytic reaction. When aspartase was modified by DTNB, the enzyme activity was restored by dithiothreitol treatment, indicating that cysteine residuetsl islarel possibly at or near the active site. The pH-dependence of the inactivation rate by NEM suggested that an amino acid residue having pK value of 8.3 was involved in the inactivation. When aspartase was incubated with NEM and L-aspartate together, L-aspartate markedly protected the enzyme from inactivation by NEM, but the other reagents used did not.

• Applied Microscopy
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• 제11권1호
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• pp.29-38
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• 1981

Bacteriophage f2 were treated with ozone at various concentrations for 20 minutes. The inactivation kinetics of f2 phage were examined during ozonation. In order to study the mode of action of ozone on the phage f2, absorption of the phage to the host pili was meassured by utilyzing radioactivity of tritium incorporated into the phage RNA. Sucrose density gradient analysis and electron microscopy were also used to prove the mechanism of ozone inactivation of the phage. Strucural proteins of the phage were broken by ozonation into many protein subunits. The extent of phage breakage was proportional to ozone concentration and reaction time. Percent decrease of the phage absorption to the host pili was coincident with the rate of ozone inactivation of the phage. Ozone inactivation of bacteriophage f2 was shown to be caused by the breakage of the structural protein and blockage of the phage absorption to the host pili.

• 한국환경보건학회지
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• 제39권3호
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• pp.289-299
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• 2013

Objectives: For the field application of the dielectric barrier discharge plasma reactor, scale-up of the plasma reactor is needed. This study investigated the possibility of inactivation of microorganisms in sewage using pilot multi-plasma reactor. We also considered the possibility of degradation of total organic carbon (TOC) and nonbiodegradable matter ($UV_{254}$) in sewage. Methods: The pilot plasma reactor consists of plasma reactor with three plasma modules (discharge electrode and quartz dielectric tube), liquid-gas mixer, high voltage transformers, gas supply equipment and a liquid circulation system. In order to determine the operating conditions of the pilot plasma reactor, we performed experiments on the operation parameters such as gas and liquid flow rate and electric discharge voltage. Results: The experimental results showed that optimum operation conditions for the pilot plasma reactor in batch experiments were 1 L/min air flow rate), 4 L/min liquid circulation rate, and 13 kV electric discharge voltage, respectively. The main operation factor of the pilot plasma process was the high voltage. In continuous operation of the air plasma process, residual microorganisms, $UV_{254}$ absorbance and TOC removal rate at optimal condition of 13 kV were $10^{2.24}$ CFU/mL, 56.5% and 8.6%, respectively, while in oxygen plasma process at 10 kV, residual microorganisms, $UV_{254}$ absorbance and TOC removal rate at optimal conditions were $10^{1.0}$ CFU/mL, 73.3% and 24.4%, respectively. Electric power was increased exponentially with the increase in high voltage ($R^2$ = 0.9964). Electric power = $0.0492{\times}\exp^{(0.6027{\times}lectric\;discharge\;voltage)}$ Conclusions: Inactivation of microorganisms in sewage effluent using the pilot plasma process was done. The performance of oxygen plasma process was superior to air plasma process. The power consumption of oxygen plasma process was less than that of air plasma process. However, it was considered that the final evaluation of air and oxygen plasma must be evaluated by considering low power consumption, high process performance, operating costs and facility expenses of an oxygen generator.

• 한국동물학회지
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• 제32권4호
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• pp.305-313
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• 1989

The present investigation aims at inquiring into a possible target for the heat inactivation of SCK tumor cells by comparing the kinetics of cell survival, rate of protein synthesis, and DNA polymerase activity in the presence of heat protector or heat sensitirer. A possible conclusion to be drawn from the present experiment is that there is no direct correlation between cell death and decrease in the rate of protein synthesis, but that the loss of DNA polvmerase $\beta$ activity correlates quite well with cell inactivation. Thus, protein degrada-tion and/or abnormal protein synthesis causes cell inactivation innireuv, possibly by altering the cellular environment which in turn affects the DNA polymerase $\beta$ activity. Accordingly, further studies, dealing with the correlation between changes in the cellular environment and DNA polymerase $\beta$ activity, are needed to set insight into a possible target for the heat inactivation of cells. 본 연구는 열보호제 또는 열증감제의 존재하에서 세포 생존곡선, 단백질 합성률, DNA 중합효소 $\beta$의 활성변화를 비교 검토함으로써 SCK 종양세포가 열에 의해서 불활성화될 때의 표적이 무엇인지를 밝혀보기 위해서 수행되었다. 본 실험의 결과로 추정하건대 열에 의한 세포치사는 단백질 합성률의 변화와는 직접적인 연관성이 없으나, DNA 중합효소 $\beta$의 활성도와는 밀접한 연관성이 있음을 알 수 있다. 즉, 단백질의 분해 또는 비정상적인 단백질의 합성이 세포의 환경을 변화시키고 이것이 DNA 중합효소 $\beta$의 활성에 영향을 미침으로써 간접적으로 세포의 치사를 초래할 것으로 짐작할 수 있다. 따라서, 세포의 열불화성화의 표적을 좀더 분명히 밝히기 위해서는 세포의 환경변화와 DNA 중합효소 $\beta$의 활성과의 관계를 추구하는 연구가 수행되어야 할 것으로 사료된다.

• 한국환경과학회지
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• 제23권5호
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• pp.985-993
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• 2014

For the field application of dielectric barrier discharge plasma reactor, a multi-plasma reactor was investigated for the inactivation of microorganisms in sewage. We also considered the possibility of degradation of non-biodegradable matter ($UV_{254}$) and total organic carbon (TOC) in sewage. The multi-plasma reactor in this study was divided into high voltage neon transformers, gas supply unit and three plasma modules (consist of discharge, ground electrode and quartz dielectric tube). The experimental results showed that the inactivation of microorganisms with treated water type ranked in the following order: distilled water > synthetic sewage effluent >> real sewage effluent. The dissolved various components in the real sewage effluent highly influenced the performance of the inactivation of microorganisms. After continuous plasma treatment for 10 min at 180 V, residual microorganisms appeared below 2 log and $UV_{254}$ absorbance (showing a non-biodegradable substance in water) and TOC removal rate were 27.5% and 8.5%, respectively. Therefore, when the sewage effluent is treated with plasma, it can be expected the inactivation of microorganisms and additional improvement of water quality. It was observed that the $NH_4{^+}$-N and $PO{_4}^{3-}$-P concentrations of sewage was kept at the constant plasma discharging for 30 min. On the other hand, $NO_3{^-}$-N concentration was increased with proceeding of the plasma discharge.

• Bulletin of the Korean Chemical Society
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• 제8권4호
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• pp.280-285
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• 1987

FMN-dependent glycolate oxidase from spinach is inactivated by diethyl pyrocarbonate at pH 7.0. Inactivation of both apo- and holoenzyme by diethyl pyrocarbonate follows pseudo-first-order kinetics and first order with respect to the reagent. A series of difference spectra of inactivated and native enzymes show a single peak at 240 nm, indicating the modification of histidyl residues. No decrease in absorbance at around 280 nm due to formation of O-carbethoxytyrosine is observed. The rate of inactivation is dependent on pH, and the data for pH dependent rates implicate the involvement of a group with a pKa of 6.9. The activity lost by treatment with diethyl pyrocarbonate could be almost fully restored by incubation with 0.75M hydroxylamine. The reactivation by hydroxylamine and the pH dependence of inactivation are also consistent with that the inactivation is due to modification of histidyl residues. Although coenzyme FMN is without protective effect, the substrate glycolate, the product glyoxylate, and two competitive inhibitors, oxalate and oxalacetate, provide marked protection against the inactivation of the holoenzyme. These results suggest that the inactivation of the oxidase by diethyl pyrocarbonate occurs by modification of essential histidyl residue(s) at the active site.

• 한국환경과학회지
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• 제21권7호
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• pp.797-804
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• 2012

A dielectric barrier discharge (DBD) plasma reactor was investigated for the inactivation of Ralstonia Solanacearum which causes bacterial wilt in aquiculture. The DBD plasma reactor of this study was divided into power supply unit, gas supply unit and plasma reactor. The plasma reactor consisted of a quartz dielectric tube, discharge electrode (inner) and ground electrode (outer). The experimental results showed that the optimum 1st voltage, 2nd voltage, air flow rate and pH were for 100 V (1st voltage), 15 kV (2nd voltage), 4 L/min, and pH 3, respectively. At a low 1st voltage, shoulder and tailing off phenomena was observed. The shoulder phenomenon was decreased as the increase of 1st voltage. R. Solanacearum disinfection in the lower air flow rate was showed shoulder and tailing off phenomenon because the active species generated less. Under optimum condition, shoulder and tailing off phenomenon was reduced. When the 2nd voltage was less than 7.5 kV, tailing off phenomenon was observed and this was not vanishes even though the increase of the disinfection time. The inactivation efficiency increased as the increase of air flow rate, however, the efficiency decreased when the air flow rate was above 4 L/min. R. Solanacearum disinfection at pH 3 showed somewhat higher than in pH 11. The pH effect of R. Solanacearum deactivation is less than the impact on other factor.