• Journal of Pharmaceutical Investigation
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• v.15 no.3
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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.

• Journal of Life Science
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• v.10 no.6
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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 $Pb(NO_3)_2$.

• Korean Journal of Pharmacognosy
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• v.36 no.1 s.140
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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.

• Korean Journal of Soil Science and Fertilizer
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• v.17 no.1
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• pp.77-81
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• 1984

Paddy soil samples were collected from the plow layers of 19 soil series distributed in Yeongnam district to determine the relationship between soil urease activity and other soil characteristics. The results obtained were summarized as follows: 1. Simple correlation analyses showed that the urease activity was positively related with available $P_2O_5(r=.844^{**})$, potassium activity ratio($r=0.762^{**}$), available $SiO_2(r=.580^{**})$ and $SiO_2$/O.M ratio($r=0.591^{**}$). 2. Among soil chemical properties which had positive linear correlations with soil urease activity, the content of available $P_2O_5$ in soil had the highest contribution to the multiple regression equation of soil urease activity. 3. The activity of soil urease was especially lower in sandy texture than in clayey paddy soils, and a tendency was observed that the heavier soil textures the higher activity of soil urease. 4. Relatively well drained soils had the higher activity of soil urease while the soils in "poorly drained" had remarkably lower activity of soil urease. 5. The soils in higher classes of paddy soil equitability group had higher activities of soil urease.

• KSBB Journal
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• v.19 no.5
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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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• v.23 no.1
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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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• v.23 no.3
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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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• v.19 no.3
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• pp.187-191
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• 2004

Among 14 medicinal plants selected for the study ethanol (70%) extract of Coptis japonica Makino showed the highest anti-microbial activity against Helicobacter pylori followed by Perilla frutescens var. acuta KUDO, Caesalpinia sappan L. and Schizonepeta tenuifolia Briq. However, anti-urease activity of methanol (80％) extracts was best for Forsythiae Fructus followed by Caesaipinia sappan L. and Schizonepeta tenuifolia Briq. In the second fractionation using water, ethyl acetate and butanol more than 90％ of the anti-urease activity was detected in the ethyl acetate fraction.

• Korean Journal of Soil Science and Fertilizer
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• v.21 no.4
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• pp.380-385
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• 1988

The urease adsorption on zeolite and the various properties of adsorbed urease were investigated to find out the influence of zeolite on activity and properies of urease. Free urease in solution was adsorbed on zeolite untill the max. adsorption, and the amount of max. adsorption was 11.3mg urease/100mg zeolite at pH 7.0. It is apparent that free urease was adsorbed on the outer surface of zeolite by cation exchange reaction, and more than 70% of urease adsorption was adsorbed within 30 min. The activity of adsorbed urease was decreased by 89.6%, whereas Km value was increased to 34.4mM, which is higher than that of free urease. The optimum pH of adsorbed urease was widened 6.5 to 7.0, compared to that of free urease 7.0. The resistance of urease to protease became weaker by adsorption, however substrate specificity and thermal stability were not affected.

• Journal of Microbiology and Biotechnology
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• v.8 no.6
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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).