• 한국토양비료학회지
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• 제21권4호
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• pp.380-385
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• 1988

Zeolile에 의한 Urease의 활성(活性)과 특성(特性)에 미치는 영향(影響)을 구명(究明)하기 위하여, Zeolite의 Urease 흡착양상(吸着樣相)과 흡착(吸着)된 Urease의 여러가지 성질(性質)들을 조사(調査)하였다. Zeolite의 존재하(存在下)에서 용액중(溶液中)에 유리(遊離)된 Urease는 흡착(吸着)이 최대(最大)에 도달(到達)할 때까지 Zeolite에 흡착(吸着)되며, pH 7.0에서의 최대흡착량(最大吸着量)은 11.3mg urease/100mg Zeolite이었다. Zeolite에 의한 Urease의 흡착(吸着)은 주로 정전기적(靜電氣的) 결합(結合)에 의하여 Zeolite의 외표면(外表面)에서 이루어지며, 흡착량(吸着量)의 70%이상(以上)이 30분(分) 이내(以內)에 흡착(吸着)되었다. 흡착(吸着)된 Urease는 Free Urease에 비(比)하여 활성(活性)이 89.6%나 감소(減少)되었으며, Km치(値)는 3배(倍) 이상(以上)이나 증가(增加)된 34.4mM이었다. 흡착(吸着)된 Urease의 최적(最適) pH는 6.5~7.0으로 Free Urease의 7.0에 비하여 그 범위(範圍)가 넓어졌으며, Protease에 대한 저항성(抵抗性)은 약(弱)하여 졌다. 또한, 기질특이성(基質特異性)과 열(熱)에 대한 안정성(安定性)에는 변화(變化)가 없었다.

• Journal of Applied Biological Chemistry
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• 제60권2호
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• pp.173-178
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• 2017

본 연구는 요소비료를 처리할 때 가수분해가 일어나 암모니아로 휘산되어 손실되는 것을 억제하기 위한 목적으로 목초액이 요소분해에 미치는 영향을 규명하고자 하였다. 기존에 수많은 요소분해 합성억제제들이 개발 또는 탐색되어 왔으나, 토양 또는 환경 별로 효과가 일정치 않고 합성물질의 경우 환경에 미치는 영향을 고려해야 한다는 점 등 때문에 그 사용이 제한되고 있는 실정이다. 본 연구에서는 친환경 농업자재인 목초액이 토양 중 요소분해에 미치는 영향을 요소분해효소(urease)활성 억제효과를 통해 평가하였다. 목초액은 식물 urease와 미생물 urease 활성저해 효과뿐만 아니라 다양한 urease complex가 존재하는 토양 urease에도 저해효과를 보였다. 이러한 요소분해효소의 저해는 jack bean urease 반응속도를 측정한 결과 non-competitive inhibition으로 판단된다. 또한 목초액을 요소와 함께 토양에 처리하였을 경우 토양 내 요소분해작용을 억제하였다. 이를 통해 목초액을 요소 비료와 같이 처리할 경우 식물에 공급되는 질소의 효율을 증진시킴과 동시에 토양에 공급되는 질소비료의 총량을 절감하여 친환경 농업에 도움이 될 것으로 판단된다.

• Journal of Microbiology and Biotechnology
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• 제14권2호
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• pp.330-336
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• 2004

Fifty-two pathogenic Vibrio parahaemolyticus strains were isolated from the environments of Busan and Yeosu, Korea. Forty-three of these strains showed protease activities, whereas 4 strains showed $\alpha / \beta$ hemolysin activities and 6 strains had urease activities. Their pathogenic factors were not overlapping except one strain, which had both protease and hemolysin activities. The 6 urease-positive strains (V. parahaemolyticus YKB4, YKB14, S25, YFB20, YFO21, and YFO22) showed the same biochemical characteristics as a reference strain [V. parahaemolyticus KCTC 2471 (urease-negative)], except for urease production. The 6 urease-positive strains showed different urease activities in their culture supernatant during the growth. The urease activity of S25 increased sharply at the late exponential phase, and was the highest at the initial stationary phase and was kept until the late stationary phase. The other 5 isolates, except C25, showed urease activities at the mid-stationary phase and increased steadily until the late stationary phase, when the urease activity was maximal. To compare the degree of virulence of V. parahaemolyticus with different pathogenic factors, hemolysin, protease, or urease-positive strains were injected into groups of 10 each of ICR mice (7- to l0-week-old males). The lethal rates of urease-positive V. parahaemolyticus, YKB14, YKB4, and S25, were significantly high, being 50, 70, and 80%, respectively. Protease-positive V. parahaemolyticus strains FM39 and FM50 showed 40% and 60% of lethal rate, respectively. Hemolysin-positive V. parahaemolyticus strains S34 and S72 had no mortality, similar to nonpathogenic V. parahaemolyticus FM12.

• 생명과학회지
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• 제13권1호
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• pp.67-72
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• 2003

위염, 위궤양 및 위암의 원인 균인 Helicobacter pylori 가균체 표면에 다량 함유하며 주된 생존 인자이며 병원성 인자인 urease를 대장균에서 발현시키고 이 효소에 대한 항체 또는 기질과의 특이 상호 작용을 이용하여 두 단계의 간편한 방법에 의하여 정제하였다. 우선 anti-H. pylori Urease IgG-Sepharose column과 urea-Sepharose column을 각각 제조하고 DEAE-Sepharose 음이온 교환수지를 통하여 1차 정제한 시료를 각각 적용하고 제반 조건에서 용출시켰다. Anti-H. pylori urease IgG-Sepharose column의 경우에는 urease 시료가 너무 강력하게 결합함으로써 극단적인 pH조건에서만 용출이 가능함이 관찰되었으므로, 100 mM 탄산 완충액(pH 10.5)으로 최종 용출하였을 때 비교적 순수한 효소를 얻었으나, 비활성이 다소 감소된 것으로 나타났다. 한편, urea-Sepharose에 적용시킨 시료는 100 mM urea-HEB 완충액(pH 7.5)으로 비교적 용이하게 용출되어 비교적 높은 순도와 비활성의 urease 효소를 얻을 수 있었으나 이 경우에는 urease의 smaller subunit인 UreA peptide band의 강도가 다소 감소한 것이 관찰되었다.

• 한국토양비료학회지
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• 제21권1호
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• pp.73-78
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• 1988

답토양(畓土壤)에서 요소(尿素)의 분해양상(分解樣相)과 관련(關聯)한 urease의 Kinetic특성(特性)을 알기위해서 토양(土壤)의 이화학성(理化學性)과 urease활성(活性)이 상이(相異)한 4개(個) 토양(土壤)을 사용(使用)하여 toluene처리(處理) 및 무처리(無處理) 조건(條件)에서 시간별(時間別) 요소(尿素)의 분해량(分解量)과 요소(尿素) 농도별(濃度別) urease활성(活性)을 측정(測定)한 결과(結果)는 다음과 같았다. Toluene 무처리(無處理) 조건(條件)에서는 총(總) urease활성(活性)이 높은 강서(江西) 사양토(砂壤土)에서 요소(尿素)의 분해(分解)가 가장 빨랐고 1차반응속도정수(次反應速度定數)와 Km 및 Vmax치(値)도 가장 높았으며 그 다음은 호남(湖南) 미사식양토(徵砂値壤土)> 장천양질사토(長川 壤質砂土)> 광포(廣浦)(염해답(鹽害畓)) 사용토(砂壤土) 순(順)이었다. 그리고 tolune처리(處理)는 전(全) 토양(土壤)에서 요소(尿素)의 분해(分解)를 지연(遲延)시켰으며 토양축적(土壤蓄積) urease활성(活性)이 가장 느렸으며 1차반응속도수(次反應速度定數)와 Km 및 Vmax값도 가장 낮았다. 그리고 토양(土壤)에 축적(蓄積)된 urease의 Km치(値)가 미생물(微生物) 분비(分泌) urease의 Km치(値)보다 적었으며, 미생물(微生物) 분비(分泌) urease의 Km치(値)는 토양간(土壤間)에 차이(差異)가 경미(輕微)하였다.

• 생명과학회지
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• 제10권1호
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• pp.94-100
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• 2000

Urease is an important microbial enzyme and its production is a marker to predict potential pathogenicity. An unusual halophilic bacterium producing urease was isolated from sea product and identified as Vibrio parahaemolyticus KH410. Its biochemical properties were indole negative, gelatin positive, sodium citrate positive and Kanagawa positive whereas other characteristics were identical as the standard strain except it showed a positive reaction on Christensen's urea agar. V. parahaemolyticus urease production was directly related to urea concentration. The production of urease was noticeable by the addition of 0.2% urea, 0.5% glucose, 2% NaCl in LB broth, and the initial pH of 5.5. The maximum production reached after 6 hr of incubation at 37$^{\circ}C$. However, NiCl2, metal ions, phosphorus did not affect production of urease.

• Advances in Traditional Medicine
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• 제5권1호
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• pp.43-47
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• 2005

Jack bean urease was immobilized on gelatin beads with the help of glutaraldehyde. The optimum immobilization (67.6%) was obtained at 30mg/ml gelatin concentration, 0.5 mg/bead enzyme protein concentration, 1 % glutaraldehyde and at $4^{\circ}C$ incubation temperature. The $t_{1/2}$ of immobilized urease was approximately 90 days at $4^{\circ}C$ compared with $t_{1/2}$ of 20 days for the soluble urease, under identical condition. The apparent optimum pH shifted from 7.3 to 8.0 when the urease was immobilized. The optimum stability temperature of immobilized urease was found to be $60^{\circ}C$ while that of soluble urease was $45^{\circ}C$. Time-dependent thermal inactivation studies showed monophasic kinetics for soluble urease and immobilized urease at $70^{\circ}C$, respectively. The immobilized urease beads stored at $4^{\circ}C$ showed practically no leaching over a period of 30 days. Here we are presenting an easy and economical way of immobilizing urease on the gelatin beads making it suitable for various applications.

• 아시안잔디학회지
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• 제6권1호
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• pp.23-28
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• 1992

Urea, the major N source of world agriculture involves a serious urea-N loss through NH$_3$volatilization. Approaches to decrease N loss include using urease inhibitors in view of the environmental protection and the increase of urea-N efficiency. The purpose of laboratory researches was toassess the potential value of urease inhibitors to increase urea-N efficiency in soil and Kentucky blue-grass(Poa Pratensis L.) turf. The activity of urease inhibitors Phenyiphosphorodiamjdate(ppD) and N-(n-butyl) thiophosphoric triamjde(NBPT) measured to break-down ammonia volatilization. The soil and turf used in this project were from the fairway in one of the Korean gof course. The researches were carried out for two weeks to measure the urease activities on urea hydrolysis under four temperatures (10~ 40$^{\circ}C$) and for one week on turfgrass using forced-draft system. Results indicated that Urea-N involves considerable loss through gaseous NH$_3$ by urease activities in plant-soil systems. Urease inhibitors PPD and NBPT have potential value for increasing N use efficiency by reduing NH$_3$ volatilization. NBPT deserves futher evaluation as fertilizer amendment than PPD use of urea in turf industries.

• Journal of Pharmaceutical Investigation
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• 제15권3호
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• pp.93-99
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• 1985

For the effective immobilization of urease on chitosan matrix with glutaraldehyde, optimal activation methods were studied, and its enzymatic properties was investigated. In the stability of enzyme. the retained activity of the native urease was 55% after it was soaked af pH 7 for 10 hrs., while the retained activity of immobilized one was about 62% after soaked at pH 6.5-8.5 for the same time. After heat treatment at $60^{\circ}C$ for 10 hrs., the native urease lost the most of its activity, while immobilized urease retained 54% of its activity by the same treatment. The retained activity of immobilized urease did not decrease nearly when it was stored at room temperature for 25 days. From Linweaver-Burk plots, the $V_{max}$ value of native urease was $66{\mu}M/l$ and that of immobilized urease was $41{\mu}M/l$, while Km value 40mM/l for both enzymes was unaltered.

• 생약학회지
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• 제36권1호통권140호
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• pp.56-59
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• 2005

Urease plays an important role in the urea metabolism and the effect of urease activity on human and environment is enormous. For instance, urease acts as a virulence factor of the urinary and gastrointestinal tracts infections in human and animal, being involved in kidney stone formation, catheter encrusatation, pyelonephritis, ammonia encephalopathy, hepatic coma, and urinary tract infections. Widespread urease activity in soil induces a plant damage due to ammonia toxicity and pH increase. Therefore, urease activity regulation through urease inhibitors would lead to an enhanced efficiency of urea nitrogen uptake in plants and to the improved therapeutic strategies for ureolytic bacterial infections. To search for new inhibitory compounds on urease activity from herbs, MeOH extracts of herbs were screened. Among of them, the MeOH extracts of Areca catechu exhibited an excellent inhibitory effect on urease activity. Two compounds were isolated from the ethyl acetate fraction by the activity guided fractionation. Their chemical structures were identified as (+)-catechin(compound I) and allantoin(compound II) by spectroscopic evidence, respectively. Compound I showed a stronger inhibitory effect on urease activity than compound II.