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 heterobifunctional reagent, N-succinimidyl 3-(2-pyridyldithio)propionate, was synthesized. Its N-hydroxysuccinimide ester group reacts with amino groups and the 2-pyridyl disulphide structure reacts with aliphatic thiols. A new thiolation procedure for proteins is based on this reagent. The procedure involves two steps. First, 2-pyridyl disulphide structures are introduced into the protein by the reaction of some of its amino groups with the N-hydroxysuccinimide ester sie of the reagent. The protein-bound 2-pyridyl disulphide structures are then reduced with dithiothreitol. This reaction can be carried out without concomitant reduction of native disulphide bonds. The technique has been used for the introduction of thiol groups de novo into ribonuclease, gamma-globulin, alpha-amylase and horseradish peroxidase. N-Succinimidyl 3-(2-pyridyldithio)propionate can also be used for the preparation of protein-protein conjugates. This application is based on the fact that protein-2-pyridyl disulphide derivatives (formed from the reaction of non-thiol proteins with the reagent) react with thiol-containing proteins (with native thiols or thiolated by, for example, the method described above) via thiol-disulphide exchange to form disulphide-linked protein-protein conjugates. This conjugation technique has been used for the preparation of an alpha-amylase-urease, a ribonuclease-albumin and a peroxidase-rabbit anti-(human transferrin) antibody conjugate. The disulphide bridges between the protein molecules can easily be split by reduction or by thiol-disulphide exchange. Thus conjugation is reversible. This has been demonstrated by scission of the ribonuclease-albumin and the alpha-amylase-urease conjugate into their components with dithiothreitol. N-Succinimidyl 3-(2-pyridyldithio)propionate has been prepared in crystalline form, in which state (if protected against humidity) it is stable on storage at room temperature (23 degrees C).
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PMID:Protein thiolation and reversible protein-protein conjugation. N-Succinimidyl 3-(2-pyridyldithio)propionate, a new heterobifunctional reagent. 70 70

Three types of organic polymers and bead-shape silica gels were activated by graft polymerization of 2,3-epoxypropyl methacrylate; in some cases, epoxide groups on the support surface were modified to NH2 groups. Eight active matrices so obtained were assessed as supports for immobilized enzymes using peroxidase, glucoamylase and urease. The immobilization yield of protein and specific activities of enzymes were better with supports containing NH2 groups than with those containing epoxide spacer arms. Maximum enzyme immobilization and storage stabilities were obtained with silica-gel beads activated by graft polymerization of 2,3-epoxypropyl methacrylate. With all eight matrices tested, the immobilized enzymes showed good stability with not less than 82% of the original activity persisting after 28 days. The developed matrices have potential for use in process-scale biotechnological operations.
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PMID:Immobilization of enzymes to porous-bead polymers and silica gels activated by graft polymerization of 2,3-epoxypropyl methacrylate. 136 57

Forty-nine monoclonal antibodies against Helicobacter pylori were screened to investigate their capacity to be used in enzyme-linked immunosorbent assay (ELISA) competitive systems for the serodiagnosis of Helicobacter pylori infection. On the basis of the inhibition pattern showed by the sera of five infected patients, the antibodies were subdivided into five groups. The immunoblotting analysis showed that the antibodies recognized a total of nine different antigenic determinants. In a study of the reaction of the antibodies with 12 isolates of H. pylori a total of 9 antigenic profiles were identified. Two monoclonal antibodies, HpN44 and HpN45, which recognized a 64-kD protein, were inhibited by all 5 positive sera. Antibody HpN45 was labeled with horseradish peroxidase, and the competitive ELISA was compared with an ordinary indirect ELISA in a study of 102 patients undergoing gastroscopy. Seventy-three patients proved to be infected by H. pylori according to urease or histologic tests. The sensitivity and specificity were 90.4% and 89.6%, respectively, for the indirect ELISA and 100% and 89.6% for the HpN45 competitive assay. The three patients who were 'false seropositive' with both serologic tests had atrophic gastritis. The high diagnostic performance and simplicity of the HpN45 monoclonal competitive ELISA make it suitable for routine serodiagnosis of H. pylori infection.
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PMID:Serodiagnosis of Helicobacter pylori-associated gastritis with a monoclonal antibody competitive enzyme-linked immunosorbent assay. 164 87

We describe a new enzymic colorimetric method in which urea is measured in serum by use of a single reagent mixture. Ammonia produced by urea hydrolysis, catalyzed by urease, reacts with glutamate and ATP in the presence of glutamine synthetase. The ADP so produced is assayed in reactions catalyzed sequentially by pyruvate kinase and pyruvate oxidase in a system that generates hydrogen peroxide. The hydrogen peroxide is measured at 500 or 550 nm in a reaction catalyzed by horseradish peroxidase, with phenol/4-aminophenazone as the chromogen. The reaction is complete in 15 min at 37 degrees C. The standard curve is linear up to a urea concentration of 40 mmol/L. Precision is good; CVs ranged from 2.5% to 3.1%. Results by the present method compared well with those by a candidate Reference Method and are not subject to interferences from commonly used drugs and anticoagulants.
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PMID:Enzymic urea assay: a new colorimetric method based on hydrogen peroxide measurement. 256 17

We have developed a rapid and sensitive method for total DNA measurement using single-stranded DNA binding protein from E coli conjugated with horseradish peroxidase or urease. To detect DNA, the sample is heated or alkali treated to denature the DNA and then filtered through nylon or nitrocellulose membranes. After the single-stranded DNA is bound to the membrane, single-stranded DNA binding protein enzyme-conjugate is incubated with the membrane. Next, the unbound conjugate is washed off the membrane and the bound conjugate detected colorimetrically. The assay can detect 10 pg of DNA in less than 3 hr. This method can be applied to the detection of DNA contamination in therapeutic proteins produced by recombinant DNA or hybridoma techniques.
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PMID:Detection of total DNA with single-stranded DNA binding protein conjugates. 268 50

A rapid enzymatic assay method for ammonia was developed by using glutamine synthetase from glutamate-producing bacteria together with pyruvate kinase, lactate dehydrogenase, and NADH. The time required for determination of 25 nmol of ammonia was 5 min with 1 unit of glutamine synthetase, as opposed to 14-30 min with 1 unit of glutamate dehydrogenases from various sources. The present method was used to determine ammonia in serum, microbiol-culture broth, and waste water. The method can be modified for spectrophotometry in the visible region by substituting pyruvate oxidase, peroxidase, and appropriate chromogens for lactate dehydrogenase and NADH. With 4-aminoantipyrine (4AA) and phenol, and with 4AA and N-ethyl-N-2-hydroxyethyl-m-toluidine as chromogens, the sensitivity of ammonia determination was 0.65 and 1.7 times that with glutamate dehydrogenase, respectively. The present method was also applicable to the continuous detection of the activity of some ammonia-forming enzymes such as guanase, adenosine deaminase, and urease and to the determination of 0.5-30 microM ATP-ADP after some modification of the mixture.
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PMID:A rapid assay method for ammonia using glutamine synthetase from glutamate-producing bacteria. 288 29

The use of urease in enzyme-linked immunosorbent assays (ELISAs) offers the advantages of convenience and safety. However, urease-based ELISA, performed in standard microtitre format, could result in false positive reactions upon prolonged incubation. False positive reactions appeared when wells containing substrate solution absorbed ammonia liberated from a reactive well nearby. Thus, the intensity of the false reaction was proportional to that of the urease reaction. The transfer of ammonia was demonstrated by pyrolysis-mass spectrometry. When urease conjugates were compared with peroxidase conjugates in the detection of IgG and IgM, there was no evidence that one enzyme was superior to the other in terms of increasing the sensitivity or the speed of ELISA.
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PMID:An assessment of urease-based enzyme-linked immunosorbent assay. 318 87

Dielectric heating at frequencies of 42 and 2450 MHz was applied to whole soybeans of natural moisture content for varies exposure times. The minimum energy absorbed (MEA) was calculated from moisture-loss and temperature-elevation data. Biochemical analyses were performed to determine protein dispersibility index (PDI), nitrogen solubility index (NSI), and trypsin-inhibitor, urease, lipoxygenase, and peroxidase activities. Because the heating rates were different at the two frequencies for the power levels used, plots of the biochemical properties against temperature of exposure time showed an apparent frequency dependence. This dependence on frequency disappeared, however, when MEA was substituted as the independent variable. Chemical analyses revealed that dielectric heating of soybeans at natural moisture levels should be as effective as conventional steam toasting in reducing trypsin-inhibitor activity. PDI and NSI, but not urease, were suitable indicators of trypsin-inhibitor inactivation by dielectric heating. Lipoxygenase was completely inactivated by the dielectric-heating treatments that gave suitable trypsin-inhibitor inactivation, but peroxidase activity remained relatively high, offering possible advantages for bleaching and improved soy product color.
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PMID:Effects of 42- and 2450-MHz dielectric heating on nutrition-related properties of soybeans. 692 Apr 15

Bacteriological tests on feces of patients with ulcerative-hemorrhagic colitis, in exacerbation, were carried out. The same patients were dynamically followed up as regards clinical picture and paraclinical indices, rectoromanoscopy include. Quantitative and qualitative analysis of the fecal microflora was made according to the following indices: total number of mesophili aerobic microorganisms, coli-bacteria, proteus, enterococci, staphylococci, Salmonella-bacteria. The pure cultures isolated were tested according to 30 biochemical indices, their precise classification position being determined on that base. The production of the following enzymes was studied in the cultures isolated: protease, oxyreductase -- catalase and peroxidase, aminotransferase -- COT and GPT; phosphatase -- acid and alkaline, disaccharidase and urease. The data obtained from the bacteriological studies were compared with those of a control group of healthy subjects. Elevated enzyme constellation was found among the patients with exacerbated ulcerative-hemorrhagic colitis.
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PMID:[Intestinal bacterial microflora study in chronic ulcerohemorrhagic colitis]. 697 92

The aim of this study was to investigate the consequence of Helicobacter pylori eradication on gastric mucosa and antral G and D-cells. Forty children, aged 5-17 years with Helicobacter pylori infection were assessed. Helicobacter pylori was detected by a urease test and identified by serological and microbiological methods. Twenty children were again assessed after the therapy (the combination of colloid bismuth subcitrate, amoxycillin and metronidazole). Gastroscopic examination was performed and at least six bioptic specimens were taken from the antrum, body and fundus. Tissue samples, processed with the paraffin method and stained with hematoxyllin and eosin, were assessed. Monoclonal antiserum Gastrin PAP kit 516 and somatostatin PAP kit 512 (DAKO) in the peroxidase-antiperoxidase technique (PAP) have been used to detect G and D-cells. Helicobacter pylori in the gastric mucosa was demonstrated with the Giemsa method. The results show the coincidence of Helicobacter pylori infection and the count of antral G and D-cells and active chronic gastritis in children. After the treatment Helicobacter pylori was eradicated in 70% of children. In 34% of these cases the eradication was followed by a diminution of activity of gastric antral mucosa inflammation and in 20% of these children the resolution of the inflammatory infiltration in the gastric mucosa was seen. A decrease of the antral G and D-cells count and also a diminution of G/D index in these cases were observed.
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PMID:Morphological and immunohistochemical examinations of the dynamic changes of gastric mucosa associated with the treatment of helicobacter pylori infection in children. 877 26


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