• Journal of Microbiology and Biotechnology
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• 제8권6호
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• pp.581-587
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• 1998

Essential amino acids involved in the catalytic role of the extracellular cytosine deaminase from Chromobacterium violaceum YK 391 were determined by chemical modification studies. The enzyme activity required the reduced form of Fe (II) ion, since the enzyme was inhibited by ο-phenanthroline. The enzyme activity was completely inhibited by the chemical modifiers, such as p-chloromercuribenzoate (p-CMB), p-hydroxymercuribenzoate, and chloramine-T at 1 mM each. The enzyme activity was also markedly inhibited by pyridoxal-5'-phosphate, diethyl pyrocarbonate, and phenylmethylsulfonyl fluroride at 1 mM each. The inactivation of the enzyme activity with p-CMB was reversed by a high concentration of cytosine. Furthermore, the inactivation of the enzyme activity with p-CMB was also reactivated by 1 mM dithiothreitol, 1 mM 2-mercaptoethanol, 1 mM cysteine-HCI, 10% ethyl alcohol, and 10% methyl alcohol. These results suggested that cysteine and methionine residues might be located in or near the active site of the enzyme, while lysine, histidine, and serine residues might be indirectly involved in the enzyme activity.

• 한국축산식품학회지
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• 제27권1호
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• pp.102-109
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• 2007

Lactobacillus salivarius subsp. salivarius CNU27 possessed a high level of ${\alpha}$-galactosidase activity. Purified ${\alpha}$-galactosidase was obtained after sonication of harvested cell pellet followed by DEAE-Sephadex A-50 and Mono Q anion exchange chromatography. The specific activity of the purified enzyme was 8,994 units/mg protein which is 17.09 times higher than that in crude extract. The native enzyme was a monomer with a molecular mass of 56,397.1 dalton. The optimum temperature and pH for the enzyme were $40^{\circ}C$ and 6.0, respectively. The enzyme was stable between 25 and $50^{\circ}C$. However, ${\alpha}$-galactosidase activity was lost rapidly below pH 4.5 and above pH 8.5. The enzyme activity decreased to 6.73% and 4.30% of the original activity by addition of $Cu^{2+}$ and $Hg^{2+}$, respectively. Other metal compounds did not affect the enzyme activity significantly. The enzyme liberated galactose from melibiose, raffinose, and stachyose. The rate of substrates hydrolysis was measured by HPLC. Raffinose, stachyose and melibiose were completely decomposed after 24 hr at $40^{\circ}C$.

• 한국미생물·생명공학회지
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• 제30권1호
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• pp.33-38
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• 2002

Lactobacillus plantarum 용균 효소를 생산하는 균주를 배양하여 생산된 효소를 정제한 결과 비활성도가 5.8 units/mg protein 이었고 정제도 8.3배, 수율은 30%이었다. 정제효소의 분자량은 gel filtration과 SDS-polyacrylamide gel eletrophoresis를 이용하여 측정한 결과 60,000 kDa 이었다. 용균 효소의 최적 반응 시간은 20분이었으며 최적 온도는 4$0^{\circ}C$, 최적 pH는 3.0이었다. 온도 안정성은 각 온도에서 30분간 처리하였을 때 $30^{\circ}C$까지는 안정하였으나 4$0^{\circ}C$에서는 80% 활성을 나타내었다. 효소의 pH 안정성은 실온에서 1시간 처리하였을 때 pH 4~7에서 안정성을 나타내었다.

• 한국미생물·생명공학회지
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• 제14권6호
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• pp.467-471
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• 1986

Fusarium moniliforme으로부터 순모세포벽 분해효소를 생산하고 분리, 정제하여 효소특성 및 protoplast 제조실험을 하였다. Ammonium nitrate를 0.2％ 첨가한 Baker's yeast 배지에서 7일간 진탕배양으로 효소를 생산한 후 Ammonium sulfate로 분획하고 Sephadex(G-100) column chromatography하여 세개의 peak를 얻었다 첫 번째 peak는 proteolytic, lytic activity 및 laminarin 분해력가를 보였으며, 두 번째 Peak는 lytic activity와 laminarin 분해력가를 동시에 가지고 있었으며, 세 번째 peak는 lytic activity만을 가지고 있었다. 분리된 세개의 peak를 혼합하였을때 개개의 peak보다 훨씬 높은 역가을 나타내어 상승효과를 보였고 또한 환원제에 의한 효소력가의 상승효과도 있었다. protoplast 수율은 99.2％정도였다

• 한국미생물·생명공학회지
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• 제23권3호
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• pp.304-310
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• 1995

A thermophilic bacterium producing the extracellular cellulase-free xylanase was isolated from soil and has been identified as Bacillus sp. The optimal growth temperature was 50$\circ$C and the optimal pH, 7.0. Under the optimal growth condition, maximal xylanase production was 2.2 units/ml in the flask culture. The enzyme production was induced by xylan and xylose, but was repressed by sucrose or trehalose. The partially purified xylanase was most active at 70$\circ$C. It was found that the enzyme was stable at 65$\circ$C for 10 hours with over 75% of the activity. The enzyme was most active at pH 7.0 and retained 90% of its maximum activity between pH 5.0 and pH 9.0 though Bacillus sp. was not grown on alkaline conditions (>pH 8.0). In addition, the activity of xylanase was over 60% at pH 10.0. At the ambient temperature, the enzyme was stable over a pH range of 5.0 to 9.0 for 10 h, indicating that the enzyme is thermostable and alkalotolerant. The activity of xylanase was completely inhibited by metal ions including Hg$^{2+}$ and Fe$^{2+}$, while EDTA, phenylmethylsulfonyl fluoride (PMSF), $\beta$-mercaptoethanol and SDS didn't affect its activity. The enzyme was also identified to exert no activity on carboxymethylcellulose, laminarin, galactomannan, and soluble starch.

• 약학회지
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• 제38권2호
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• pp.211-217
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• 1994

Copper intoxication and disturbance of copper metabolism induced various oxygen-derived free radicals related damages. The effect of copper ion on xanthine oxidase activity and type conversion of the enzyme which is concerned to generation of reactive oxygen species, was investigated, It was observed that xanthine oxidase activity was increased by addition of copper ion in the reaction mixture in proportional to the concentration of the metal ion until $60\;{\mu}M$, while the enzyme activity was inhibited in higher concentration of copper treatment. On the other hand, xanthine dehydrogenase activity was inhibited by copper ion addition with concentration dependently. Preincubation of enzyme source with $30\;{\mu}M$ of copper ion, which concentration marked increased the xanthine oxidase activity, unchanged the enzyme activity and type conversion compare to control in vitro system. It was also observed that copper induced xanthine oxidase activity and the enzyme type conversion was protected by dithiothreitol and penicillamine. These results indicate that the increment of the type conversion of xanthine oxidase necessarilly need the presence of copper ion in enzyme assay system.

• BMB Reports
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• 제28권5호
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• pp.443-450
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• 1995

Cloned staphylococcal peptidoglycan hydrolase was used in determining the physiological characteristics of peptidoglycan hydrolase. This enzyme hydrolyzed the bacterial cell walls and released the N-terminal alanine, but not the reducing groups. This cloned gene product was localized in the cytoplasm of transformed Escherichia coli. Activity gels indicated the enzyme had an Mr of about 54,000, which was consistent with the deduced Mr from sequencing of the cloned gene. The activity bound to CM-cellulose but not DEAE-cellulose resin, indicating it as a basic protein. Enhanced enzyme activity in a low concentration of cations, and inhibited enzyme activity in a solution with dissolved phospholipids, suggested that the activity and the availability of this basic protein may be regulated between negatively charged and positively charged cellular molecules. The activity against boiled crude cell wall was much greater than against purifed cell wall, suggesting protein associated with crude cell wall may aid in the binding of the peptidoglycan hydrolase The cloned peptidoglycan hydrolase showed positive activity on whole cells of some lysostaphin-resistant coagulase-negative staphylococci. The cloned enzyme may be an alternative for lysostaphin for lysis of staphylococci.

• 한국미생물·생명공학회지
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• 제23권1호
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• pp.75-80
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• 1995

Dextranase produced by Flavobacterium multivorum HL-1 isolated from soil were characterized. Optimum growth condition for the production of the enzyme by the strain appeared to be at the 1.0% concentration of dextran. When NH$_{4}$N0$_{3}$ and beef extract was added to the culture media, the enzyme activity increased upto 570 and 680 units per ml respectively, and other nitrogen sources did not increase the activity. Urea, casamino acid, (NH$_{4}$)$_{2}$SO$_{4}$ and KNO$_{3}$ inhibited the activity. In the presence of Mg^{2+} in culture media, the enzyme activity increased 124%, but its activity was inhibited in the presences of Ca$^{2+}$, Co2$^{2+}$, Hg^{2+} and Zn$^{2+}$ . The optimum temperature for the enzyme activity was 45-55$\CIRC$C . In the ranges of pH 4 to 10, the activity of the enzyme appeared approximately similar.

• 한국미생물·생명공학회지
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• 제6권1호
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• pp.33-40
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• 1978

Immobilization of alkaline protease was investigated by absorbing the enzyme on adsorbents. Alkaline protease was adsorbed on silica gel selected as a carrier to immobilize the enzyme. In this study, properties of the immobilized enzyme were compared with those of the soluble enzyme. 1) The optimum pH (10.0) of the enzyme was not changed, but the activity was increased at alkaline pH by immobilization. 2) The optimum temperature of the immobilized enzyme was shifted from 50$^{\circ}C$ to 45$^{\circ}C$, while the temperature-activity Profile became broader than those of the soluble enzyme. 3) The pH stability of the immobilized enzyme was significantely increased at pH 4.0, althouth it did not change in the neutral and alkaline pH region. 4) The heat stability of the enzyme was enhanced in the temperature range of 55$^{\circ}C$∼65$^{\circ}C$ by the immobilization. 5) The immobilized enzyme retained 40％ of its original activity after repetitive use for 6 times. 6) The enzyme stability was greately improved for a prolonged storage at 4$^{\circ}C$.

• Journal of Microbiology and Biotechnology
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• 제26권6호
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• pp.1087-1097
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• 2016

An intracellular lipase from Anoxybacillus flavithermus HBB 134 was purified to 7.4-fold. The molecular mass of the enzyme was found to be about 64 kDa. The maximum activity of the enzyme was at pH 9.0 and 50℃. The enzyme was stable between pH 6.0 and 11.0 at 25℃, 40℃, and 50℃ for 24 h. The K_m and V_max of the enzyme for pNPL substrate were determined as 0.084 mM and 500 U/mg, respectively. Glycerol, sorbitol, and mannitol enhanced the enzyme thermostability. The enzyme was found to be highly stable against acetone, ethyl acetate, and diethyl ether. The presence of PMSF, NBS, DTT and β-mercaptoethanol inhibited the enzyme activity. Hg²⁺, Fe³⁺, Pb²⁺, Al³⁺, and Zn²⁺ strongly inhibited the enzyme whereas Li⁺, Na⁺, K⁺, and NH₄⁺ slightly activated it. At least 60% of the enzyme activity and stability were retained against sodium deoxycholate, sodium taurocholate, n-octyl-β-D-glucopyranoside, and CHAPS. The presence of 1% Triton X-100 caused about 34% increase in the enzyme activity. The enzyme is thought to be a true lipase since it has preferred the long-chain triacylglycerols. The lipase of HBB 134 cleaved triolein at the 1- or 3-position.