• 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.

• 생명과학회지
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• 제10권6호
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• pp.558-563
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• 2000

Effect of inhibitors on Vibrio parahaemolyticus cell growth and its urease activity was studied. The growth of the bacterium and the enzyme activity were inhibited by the addition of 0.02% p-hydroxymercuric benzoate, $HgCl_2$and $AgNO_3$. However, same concentration of boric acid, thallium acetate and $Pb(NO_3)_2$ did not affect the cell growth but inhibited urease activity by 25%, 29%, and 38%, respectively. Acetohydroxamic acid was the most potent inhibitor on cell growth by inhibiting 40% but did not affect urease activity. To investigate the effect of inhibitors on urease activity, urease was purified and confirmed on SDS-PAGE. The purified urease was inhibited 100% by the addition of 1 mM acetohydroxamic acid and $AgNO_3$but no inhibition was occurred by the addition of the same concentration of thallium acetate. and the addition of 0.01 mM of $HgCl_2$ and acetohydroxamic acid inhibited the purified urease activity by 39% and 24%, respectively. On 0.1 millimolar basic, acetohydroxamic acid and $HgCl_2$inhibited 4 times more active in urease inhibition than p-hydroxymercuric benzoate whereas no inhibition was occurred either thallium acetate or $Pb(NO_3)_2$.

• 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.

• 한국토양비료학회지
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• 제17권1호
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• pp.77-81
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• 1984

영남지역(嶺南地域) 답토양(畓土壤)의 이화학적(理化學的) 성질(性質)과 토양중(土壤中)의 urease 활성(活性)과의 관계(關係)를 검토(檢討)해 본 결과(結果) ; 1. 토양(土壤) 화학적(化學約) 성분(成分)과 urease 활성(活性)과는 유효인산(有效燐酸)($r=0.844^{**}$), 가리활성도비(加里活性度比)($r=0.762^{**}$), 유효규산(有效珪酸)($r=0.580^{**}$), $SiO_2$/O.M비(比)($r=0.591^{**}$) 등(等)과는 유의(有意)한 정상관(正相關) 관계(關係)였다. 2. 토양화학성분중(土壤化學成分中) 유기인산(有機燐酸)이 urease 활성(活性)에 미치는 기여도(寄與度)가 가장 컸다. 3. 토성별(土性別) urease의 활성(活性)은 사질토(砂質土)에서 가장 낮았으며, 토성(土性)이 식질화(埴質化)됨에 따라 증가(增加)하였다. 4. 토양(土壤) 배수등급별(排水等級別) urease 활성(活性)은 배수(排水)가 양호(良好)할수록 높았으며 배수(排水)가 불량(不良)한 답(畓)에서 낮은 경향(傾向)이었다. 5. Urease 활성(活性)이 높은 토양(土壤)이 상위등급지(上位等級地)의 답(畓)에 속(屬)하였다.

• KSBB Journal
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• 제19권5호
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• pp.348-351
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• 2004

Ethanol ($70\%$) extract of Caesalpinia sappan L. and Forsythiae suspensa Vahl. showed $84\%$ and $72\%$ of anti-urease activity against Helicobacter pylori, respectively. Among the fraction of Artemisia asiatica Nakai extract using methanol ($80\%$), water, ethyl acetate and butanol ethyl acetate fraction showed $90\%$ of the anti-urease activity.

• Restorative Dentistry and Endodontics
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• 제23권1호
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• pp.43-53
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• 1998

Dental caries is induced by organic acids produced by oral bacteria. In order to prevent dental caries, therefore, it is essential to maintain neutral pH in the oral cavity. Urea plays a major role in oral pH homeostasis. Urea is hydrolyzed by bacterial ureases to ammonia, causing a pH elevation. Streptococcus salivarius has been shown to be a major contribution to oral ureolysis. Synthesis of urease by S. salivarius appears to be constituitive, but can be greatly enhanced by low pH. It is, therefore, conceivable that ureolytic activity of S. salivarius from a carious lesion is greater than that of the bacterium from a healthy tooth. In the present study, urease activity of S. salivarius isolates from dental plaque of carious lesions was compared with that of the isolates from plaques of the teeth and the dorsum of the tongue; 45 S. salivarius strains were isofated from carious lesions(>C2) of 21 individuals with dental caries and 30 strains from 10 individuals without dental caries. The results were as follows: 1. All the 21 individuals with dental caries harbored ureolytic S. salivarius whereas 3 of 13 individuals without dental caries harbored non-ureolytic strains of S. salivarius. 2. All the 45 S. saliuarius isolates from carious lesions showed urease activity. In contrast, of 30 isolates from individuals without dental caries, 17 isolates(56.7%) did not demonstrate urease activity, or if any, very little(<5${\mu}mol$/min/mg). 3. Urease activity of the isolates from carious lesions was greater than that of the isolates from individuals without dental caries : the urease activity ranged from 42 to $381{\mu}mol$/min/mg and from 0 to $208{\mu}mol$/min/mg, respectively. 4. At acid pH(5.5), the isolates which showed intermediate urease activity at pH 7.0 demonstrated even higher activity whereas the isolate with no or lower urease activity did not show any significant difference in their activity. However, the isolates with the greatest urease activity from both individuals with and without dental caries, exhibited a rather much lower urease activity at pH 5.5. The overall results suggest that isolates may have their own urease activity but the isolates exposed to chronic acidic environment of the carious lesion might elevate urease activity of S. salivarius, which in turn, might influence on survival of S. salivarius itself and other bacteria, establishing a new oral bacterial ecosystem.

• KSBB Journal
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• 제23권3호
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• pp.239-244
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• 2008

For physiological function of aloe concentrate by ultrafiltration (UF) process, jack bean urease inhibitory activity and bentonite flocculating activity of UF aloe concentrate was investigated and compared with fresh aloe gel. Urease inhibitory activity of UF aloe concentrate ranged from 87 to 90% in 1 mL sample. Also, urease inhibitory activity of UF aloe concentrate increased about 10% by heat treatment showing the heat stability. From Lineweaver-Burk plot for UF aloe concentrate, urease inhibition pattern indicated general non-competitive inhibition. From flocculation test of UF aloe concentrate about 1% (w/v) bentonite suspension, maximum flocclulating activity of 97% was obtained at 0.5 mL addition of UF aloe concentrate/ 5 ml bentonite suspension. However, flocculating activity of 81% was obtained at 1 mL addition of UF aloe concentrate/ 5 mL bentonite suspension, which was typical flocculating behavior of polymers with re-dispersion at overdose area. FT-IR spectra of UF aloe concentrate showed the characteristic patterns of $\beta$-binding polysaccharide and less deacetylation indicating higher level of bioactive polysaccharide content.

• KSBB Journal
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• 제19권3호
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• pp.187-191
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• 2004

14종 한약재의 70% 에탄을 추출물의 Helicobacter pylori에 대한 항균활성은 황련 (Coptis japonica Makino)이 가장 뛰어 났으며, 소엽 (Perilla frutescens var. acuta KUDO), 소목 (Caesalpinia sappan L.) 및 형개 (Schizonepeta tenuifolia Briq.)의 경우에도 높은 항균활성을 나타내었다. 그러나 Helicobacter pylori의 위내 서식을 도와주는 것으로 알려진 urease 활성억제능은 연교 (Forsythiae Fructus)의 메탄올 (80%) 추출물에서 가장 높았으며, 소목 및 형개의 추출물도 높았다. 특히 연교의 경우 한약재 추출물을 넣지 않은 대조군과 비교하여 80% 이상의 활성이 억제되었다. 연교의 메탄올 추출물을 물, 에틸아세테이트 (ethyl acetate), 부탄을 순으로 분획하여 각 분획물에 대한 urease 활성억제능을 검색한 결과 에틸아세테이트 분획에서 92%의 urease 활성이 억제되었다.

• 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 Microbiology and Biotechnology
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• 제8권6호
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• pp.700-704
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• 1998

Each of the recombinant structural genes of Helicobacter pylori urease, ureA and ureB, was cloned and overexpressed as inclusion bodies. Solubilization and renaturation of the inclusion bodies were carried out, to accelerate the pairing of sulfhydryl groups and the incorporation of nickel ions, which would lead to the native structure with high enzyme activity. Rates of urea hydrolysis were monitored as an indication of in vitro activation of renatured ureases. The activation of the apoprotein using 1 mM nickel ion, 100 mM sodium bicarbonate and a 10:1 ratio of reducing power resulted in a weak urease activity (about 11% of the native urease activity encoded by pTZ 19R/ure-l). When a sparse matrix screen method originally discovered for the crystallization of proteins was used, the activity increased higher than that obtained using glutathione. The effect of polyethylene glycol (PEG) on the activity was noticeable, giving two-fold increase in the specific activity (about 11 U/mg of protein corresponding to 22% of the native urease activity encoded by pTZ19R/ure-1).