Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:6.3.4.6 (urease)
7,490 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A method for the preparation of a 150-fold purified and homogenous A. aerogenes urease is reported. The enzyme exhibited two pH optima at pH 7.0 and 7.5 in triethanolamine and phosphate buffer, respectively. The affinity of the enzyme toward its substrate increased with the increase of pH. No effect of the pH was observed on the measured temperature coefficient (Q10). There was no discontinuity in the Arrhenius plots at pH 5.4 and 7.5 but an upward discontinuity at pH 6.15 and 8.7 with transition temperature at 30 degrees C. Also, the calculated activation energies are greatly affected by the pH of the enzyme reaction mixture.
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PMID:Aerobacter aerogenes PRL-R3 urease. Purification and properties. 0 Aug 79

Urease (urea amidohydrolase, EC 3.5.1.5) was extracted from the mixed rumen bacterial fraction of bovine rumen contents and purified 60-fold by (NH4)2SO4 precipitation, calcium phosphate-gel adsorption and chromatography on hydroxyapatite. The purified enzyme had maximum activity at pH 8.0. The molecular weight was estimated to be 120000-130000. The Km for urea was 8.3 X 10(-4) M+/-1.7 X 10(-4) M. The maximum velocity was 3.2+/-0.25 mmol of urea hydrolysed/h per mg of protein. The enzyme was stabilized by 50 mM-dithiothreitol. The enzyme was not inhibited by high concentrations of EDTA or phosphate but was inhibited by Mn2+, Mg2+, Ba2+, Hg2+, Cu2+, Zn2+, Cd2+, Ni2+ and Co2+. p-Chloromercuribenzenesulfphonate and N-ethylmaleimide inhibited the enzyme almost completely at 0.1 mM. Hydroxyurea and acetohydroxamate reversibly inhibited the enzyme. Polyacrylamide-gel electrophoresis showed that the mixed rumen bacteria produce ureases which have identical molecular weights and electrophoretic mobility. No multiple forms of urease were detected.
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PMID:Purification and properties of urease from bovine rumen. 1 37

Urethral swabs from 75 males with urethritis were extracted into tryptose phosphate broth and then equal aliquots were dispensed into vials containing sucrose phosphate buffer (2SP) and urease color test medium (U-9). No antibiotics were present in the media. After transport to the laboratory, the recovery of Chlamydia trachomatis and Ureaplasma urealyticum was evaluated after inoculation into McCoy's cell cultures and agar medium, respectively. C. trachomatis was recovered from significantly more patients (17 versus 12, P = 0.03) with higher inclusion counts (P less than 0.01) in specimens transported in 2SP as compared with those in U-9 medium. No significant differences between the isolation rate of U. urealyticum and that of Mycoplasma hominis were found with the two media. The rate of inactivation of C. trachomatis and U. realyticum at 4 C was examined by means of reference strains. The inactivation of C. trachomatis was similar in both 2SP and U-9 media, but the number of inclusions was consistently greater in the 2SP medium. In contrast, the number of colony-forming units of U. urealyticum actually increased over a 24-hour period in both media. We conclude that 2SP is the best medium for the combined recovery of C. trachomatis and genital Mycoplasma. The use of one transport medium and hence a single swab culture has the obvious advantages of saving time and expense for both physician and laboratory, and for the patient it will eliminate the possible discomfort of having multiple cultures taken.
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PMID:Recovery of Chlamydia and Genital Mycoplasma transported in sucrose phosphate buffer and urease color test medium. 31 81

A large radiodense calculus in the left renal pelvis of a 22-month-old, male Great Dane disappeared one month following surgical removal of two struvite (magnesium ammonium phosphate) calculi from the right renal pelvis. The dog's urine likely became undersaturated with struvite for a sufficient period to permit dissolution of the renal calculus. Several factors may have contributed to the decrease in urine struvite concentration, including eradication of a urease-producing Proteus sp from the urinary tract and induction of polydipsia and compensatory polyuria by oral administration of sodium chloride.
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PMID:Dissolution of a struvite nephrolith in a dog. 43 42

Using the general concept of a dry multilayer analytical element, we can change chemical procedures and configurations to assay several blood components. In the assay of serum urea nitrogen, urease in the reagent layer catalyzes the hydrolysis of urea. A semipermeable membrane excludes aqueous base, but allows ammonia to diffuse to an underlying indicator layer. For the amylase determination, the enzyme hydrolyzes a dyed-starch substrate coated on top of the spreading layer; this produces small fragments, which diffuse to a registration layer. The increase of absorbance at 540 nm is correlated with amylase activity. Bilirubin complexes with a cationic polymer at the interface between the spreading and reagent layers. The direct reading at 460 nm allows determination of total bilirubin in the range 1 to 500 mg/liter. Tirglycerides are hydrolyzed in the spreading layer, and the resulting soluble glycerol readily diffuses into the reagent layer, where it is phosphorylated and subsequently oxidized by glycerophosphate oxidase to yield dihydroxyacetone phosphate and hydrogen peroxide. Peroxidase catalyzes production of a color commensurate with the hydrogen peroxide produced.
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PMID:Multilayer film elements for clinical analysis: applications to representative chemical determinations. 56 6

Wearable, 24 hrs per day, 7 days per week artificial kidneys are being developed. Patients will benefit from more even control of physiologic parameters than can be obtained with conventional intermittent dialysis. Improvement in economic and social circumstances will result. Both hemodialysis and peritoneal dialysis techniques are being miniaturized. Small REDY cartridges containing urease, zirconium phosphate, hydrouse zirconium oxide and activated carbon are being utilized to regenerate dialysate. Hemodialyzers will be worn on the forearm and include long, wide, low resistance series blood flow paths to reduce the potential for thrombosis. Peritoneal effluent is regenerated and filtered by the sorbent cartridge and automatically cycled back into the peritoneal cavity.
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PMID:In search of a 24 hours per day artificial kidney. 60 88

Filled hollow fibers were prepared and evaluated for application in hemosorption. Powdered activated carbon, urease-carbon, and macroporous ion exchange resins were used as fillers in highly permeable cellulose acetate hollow fibers. The carbon-filled hollow fibers had better mass transfer properties than encapsulated carbon in solid form. Zirconium phosphate and 2 synthetic zeolites were tested for ammonium ion adsorption from buffered saline and Ringer's salt solutions. Synthetic zeolites were found to have higher specificity and capacity for ammonium ion adsorption than zirconium phosphate. Projections are that hemosorption devices utilizing urease, carbon, and zeolites could remove all nitrogenous waste metabolites currently being treated only by dialysis. Oxystarch and oxystarch derivatives were tested for direct urea adsorption and were found unsuitable for this application.
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PMID:Sorbent-filled hollow fibers for hemopurification. 71 87

Previous reports have suggested that urease-producing bacteria play a prominent role in the formation of infection-induced urinary stones. We have carried out crystalization experiments in vitro which show that bacterial urease alkalinizes urine, thereby causing: (i) supersaturation with respect to struvite and calcium phosphate; and (ii) formation of struvite and apatite crystals. Growth of Proteus in urea-free urine or in urine which contained a urease inhibitor did not cause alkalinization, supersaturation, or crystallization of struvite and apatite. Growth of Klebsiella, Escherichia coli, or Pseudomonas was not associated with significant alkalinization, supersaturation, or crystallization. Struvite and apatite crystals dissolved in Proteus-infected urine in which undersaturation was maintained by urease inhibition. Similar results in all experiments were obtained using human urine and a synthetic urine which was devoid of matrix, pyrophosphate, or other undefined solutes. Urease-induced supersaturation appears to be the primary cause of infection-induced urinary stones.
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PMID:Urease. The primary cause of infection-induced urinary stones. 81 97

As a result of reaction of urease with graft copolymer of cellulose and polyglycidyle methacrylate or with carboxymethyl cellulose, products were synthesized, containing about 2% of chemically bound urease. Binding with the cellulose derivatives was accompanied by about two-fold decrease in urease activity. Carboxymethyl cellulose-urease and polyglycidile methacrylate-cellulose-urease might be repeatedly (for 30 cycles) used for hydrolysis of urea; the enzymatic activity of the first compound did not change, but of the second one--was decreased by 30%. Activity of the compounds was not changed after storage within 2 months in 0.1 M phosphate buffer, pH 7.0 at 4 degrees C.
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PMID:[Synthesis and study of the properties of water-insoluble products of the interaction of urease and cellulose derivatives]. 111 15

Human red blood cell ghosts were prepared by electrical haemolysis at 0 degrees C in isotonic solutions using a discharge chamber which was part of a high voltage circuit. The size distribution of the ghosts was normally distributed, the modal (=mean) volume was approx. 115 mum3, performing the electrical haemolysis in the following solution: 105 mM KCI, 20 mM NaCL, 4mM MgCl2, 7.6 mM Na2HPO4, 2.94 mM NaH2PO4, 10 mM glucose, pH 7.2. Resealing was carried out at o degrees C for 10 min (after the haemolytic step) and then for further 20 min at 37 degrees C. The mean volume of the ghost preparation could be changed by variation of the phosphate concentration in the above solution replacing a part of NaCl by phosphate (5 mM phosphate: 94 mum3, 15 mM phosphate: 135 mum3). The breakdown voltage of the ghost cell membranes measured with a hydrodynamic focusing Coulter Counter depends on the mean volume (94 mum3 = 1.04 V, 134 mum3 = 1.36 V). On the other hand, the breakdown voltage is constant throughout each size distribution pointing to an "electrically homogeneous" ghost preparation. The sensitiviity of the Coulter Counter to detect electrical inhomogeneities in the membranes of a ghost population is demonstrated by dielectric breakdown measurements of an apparently normally distributed ghost preparation containing two different "electrically homogeneous" ghost population i.e. with two different breakdown voltages. The ghost cells obtained by electrical haemolysis in the above solution containing 10mM phosphate were fairly impermeable to sucrose and behave like an ideal osometer. It is further demonstrated that ghost cells can be loaded with enzymes (e.g. urease) and drugs using this technique and that these loaded ghost cells can be used as bioactive capsules for clinical application.
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PMID:Enzyme loading of electrically homogeneous human red blood cell ghosts prepared by dielelctric breakdown. 127 24


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