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)

Six strains of a new species, Legionella sainthelensi, were isolated from freshwater in areas affected by the volcanic eruptions of Mt. St. Helens in the state of Washington. Strains of L. sainthelensi are culturally and biochemically similar to other legionellae. They grow on buffered charcoal yeast agar but not on media that lack cysteine. They are gram-negative, nonsporeforming, motile rods that are positive in reactions for catalase, oxidase, gelatin liquefaction, and beta-lactamase. They are negative in reactions for urease, hydrolysis of hippurate, reduction of nitrates, fermentation of glucose, and blue-white autofluorescence. Their cell wall fatty acid composition is qualitatively similar to those of other legionellae, with 50 to 62% branched-chain fatty acids. They contain the isobranched-chain 14- and 16-carbon acids and anteisobranched-chain 15- and 17-carbon acids and relatively large amounts of straight-chain 16-carbon acid. All strains of L. sainthelensi contain approximately equal amounts of ubiquinones Q9, Q10, Q11, and Q12, a pattern similar to those of Legionella bozemanii, Legionella dumoffi, and Legionella longbeachae. Serological cross-reactions were observed between L. sainthelensi, both serogroups of L. longbeachae, and Legionella oakridgensis. Three strains of L. sainthelensi were greater than 90% related by DNA hybridization. The type strain of L. sainthelensi, Mt. St. Helens 4, was 36% related to the type strain of L. longbeachae and 3 to 14% related to the other nine described Legionella species.
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PMID:Legionella sainthelensi: a new species of Legionella isolated from water near Mt. St. Helens. 671 10

Simple solid-phase optoelectronic sensors for penicillin, urea, and glucose are described. Triphenylmethane dyes such as bromcresol green and bromthymol blue were derivatized with glutathione and co-immobilized with appropriate enzymes to a transparent membrane sandwiched between a red-light-emitting diode and a silicon photodiode with integral amplifier. In the presence of the corresponding substrates, catalytic action in the enzyme-dye membrane perturbs the local pH and causes characteristic color changes in the membrane which are monitored as a rise or fall in the output voltage of the detector system. With enzymes such as penicillinase, urease, and glucose oxidase, the response of the optoelectronic sensors is extremely reproducible over the concentration range 0-10 mM penicillin G, urea, or D-glucose, respectively. This report describes the construction and operation of these simple, inexpensive, and reagentless optoelectronic sensors.
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PMID:Solid-phase optoelectronic sensors for biochemical analysis. 674 21

A simplified translation system coupled to DNA transcription that involves assaying the synthesis of the first dipeptide of a gene product has been described recently [Robakis, N., Meza-Basso, L., Brot, N. & Weissbach, H. (1981) Proc. Natl. Acad. Sci. USA 78, 4261--4264]. Using this dipeptide system, we have investigated the expression of genes carried on plasmids coding for beta-lactamase, ribosomal protein L12, and the chloroplast large subunit (LS) of ribulosebisphosphate carboxylase (RbuBPCase). Although all three nascent gene products begin with the sequence fMet-Ser, the formation of fMet-Ser can be used to distinguish between the synthesis of beta-lactamase and either L12 or the LS of RbuBPCase by using different serine isoacceptor tRNA species. In beta-lactamase, the serine codon is AGU, which utilizes the serine isoacceptor species tRNASer3; in L12 and the LS of RbuBPCase, the serine codewords are UCU and UCA, respectively, both of which are recognized by the serine isoacceptor species tRNASer1. By using either pure tRNASer1 or pure tRNASer3, the expression of each gene can be quantitated. In this system, guanosine-5'-diphosphate-3'-diphosphate inhibits the expression of the beta-lactamase and L12 genes but stimulates the synthesis of the LS. In addition, the ratio of fMet-Ser/fMet-Ala (L12/L10) synthesized was about 1 as compared with the ratio of 4 that has been obtained previously in vivo or in vitro protein-synthesizing systems in which the entire gene product was measured.
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PMID:Use of different tRNASer isoacceptor species in vitro to discriminate between the expression of plasmid genes. 680 42

The use of eight rapid tests for the identification of 1307 strains of mycobacteria belonging to 18 species was evaluated. The standard niacin, nitrate-reductase and catalase tests were supplemented by new tests for the detection of beta glucosidase, urease, penicillinase, trehalase and cephalosporinase. This combination of eight rapid tests was not able to replace more conventional procedures but in some cases was of value in discriminating between closely related species.
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PMID:Evaluation of rapid tests for the identification of mycobacteria. 681 37

396 Haemophilus influenzae strains were biotyped according to Kilian. 393 of the strains were assigned to biotypes I to V, while 3 strains remained unclassified. Eighty-nine per cent of the capsulated strains produced both urease and ornithine decarboxylase, biotypes I or IV, while 95 per cent of the non-capsulated strains produced only one of the enzymes, biotypes II, III, or V. Of consecutive strains from the upper respiratory tract, the incidence of beta-lactamase-positive strains was higher among capsulated than among non-capsulated strains (p less than 0.025). None of 133 non-capsulated beta-lactamase-positive strains produced both urease and ornithine decarboxylase, in contrast to 15 out of 147 non-capsulated beta-lactamase-negative strains (p less than 0.001). The type e strains were all of biotype IV and 3 of 7 consecutive strains were beta-lactamase-positive.
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PMID:Biotypes of capsulated and non-capsulated Haemophilus influenzae. Correlation between biotypes and beta-lactamase production. 697 Apr 97

Seventeen strains of Haemophilus ducreyi were isolated from genital lesions which were negative for syphilis by dark-field examination. Media used for primary isolation at various times during the study were enriched chocolate agar, chocolate agar plus vancomycin (3 microgram/ml), rabbit blood agar plus vancomycin (3 micrograms/ml), fetal bovine serum agar, and fetal bovine serum agar plus vancomycin (3 micrograms/ml). H. ducreyi was isolated on chocolate agar plus vancomycin from 10 of 14 patients found to be positive on one or more media, on rabbit blood agar plus vancomycin from 16 of 17 patients, and on fetal bovine serum agar plus vancomycin from 9 of 11 patients. Sera from six animal species were tested to determine if any would support the growth of H. ducreyi. Horse and rabbit sera supported light growth of some strains. Fetal bovine serum supported good growth of all strains included in the study. Biochemical and physiological tests were done on the 17 isolates, a reference strain of H. ducreyi, and two reference strains of Haemophilus haemoglobinophilus. The results agreed with those reported by Kilian, except that H. ducreyi produced alpha-hemolysis in stabs on rabbit blood agar and was oxidase positive, three strains were urease positive, and CO2 improved the growth of seven strains. All 17 isolates were beta-lactamase positive. The reference strains were beta-lactamase negative.
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PMID:Isolation and identification of Haemophilus ducreyi in a clinical study. 697 72

Biotyping of Haemophilus influenzae into five type and H. parainfluenzae into three types based on indole production, ornithine decarboxylase, and urease has been reported (M. Kilian, Acta Pathol. Microbiol. Scand. Sect. B 82:835--842, 1976). A commercially available test system designed for the 4-h identification of Enterobacteriaceae. Micro-ID, proved efficacious for the rapid biotyping of these two Haemophilus species. The nitrate reductase, indole production, ornithine decarboxylase, urease, and o-nitrophenyl-beta-D-galactopyranoside hydrolysis tests in Micro-ID correlated over 99% with conventional methodology. By utilizing the indole and o-nitrophenyl-beta-D-galactopyranoside tests it was possible, with 261 of 272 (96.1%) isolates, to distinguish H. influenzae from H. parainfluenzae. Cerebrospinal fluid isolates were over 90% H. influenzae biotype I, and conjunctival isolates were approximately 70% biotype II. Type b H. influenzae were predominantly biotypes I and II; these type b isolates were also overwhelmingly indole producers. Although over 90% of biotypes I and II have been reported to produce beta-lactamase, this was not confirmed by the small number of beta-lactamase producers encountered here. The 4-h Micro-ID should prove a useful mechanism, amenable to the routine clinical laboratory, for the further exploration of the association of Haemophilus with the site of isolation, antigenicity, and antibiotic resistance.
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PMID:Rapid biochemical characterization of Haemophilus species by using the micro-ID. 698 1

Preliminary results suggested that the diffusion in France of the SHV-4 extended-spectrum beta-lactamase was probably due to the spread of one single epidemic strain of Klebsiella pneumoniae. In this study, we tested various phenotypic and genotypic markers to compare K. pneumoniae strains producing this enzyme isolated in 14 French hospitals between 1987 and 1989. All of the strains were of the same capsule serotype, K25. Twelve of them were of the same biotype: weak urease activity and no sucrose fermentation. Among the six plasmid profiles observed, one accounted for eight strains. Large plasmids of 170 kb encoding SHV-4 beta-lactamase were present in all strains of K. pneumoniae and could be transferred by conjugation with high frequency to Escherichia coli J53-2 or HB101 from all except one strain. Plasmid EcoRI restriction patterns suggested that these plasmids were closely related and similar to pUD18 encoding SHV-3 beta-lactamase, originally described in France and differing from SHV-4 by one amino acid substitution. Ribotyping with EcoRI and HindIII and genomic fingerprinting with XbaI by pulsed-field gel electrophoresis were concordant and suggested that 12 of the isolates recovered from the 14 hospitals were probably the same strain. Dissemination in France of the SHV-4 extended-spectrum beta-lactamase was thus essentially due to the diffusion of a single K. pneumoniae clone.
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PMID:Molecular epidemiology of Klebsiella pneumoniae strains that produce SHV-4 beta-lactamase and which were isolated in 14 French hospitals. 781 97

Bilayer lipid membranes (BLMs) can be used as generic transducers to monitor hydrolytic enzyme reactions occurring at the membrane surface. The representative enzymatic reactions presented herein were between membrane associated urease and penicillinase with urea and penicillin, respectively. Transient electrochemical signals from BLMs which contained enzyme were obtained by proper selection of the lipid composition of membranes. Negatively charged lipid membranes composed of egg phosphatidylcholine (PC) and 35% dipalmitoylphosphatidic acid were used for this purpose. The results were consistent with an electrostatic mechanism of perturbation of the surface structure of the BLMs, where changes of local hydronium ion activity associated with the enzymatic reaction altered the extent of ionization of the headgroups of the acidic constituent of the membranes, thereby providing a transient charging current which lasted for a period on the order of seconds. The delay time for observation of the transient was directly and reproducibly related to the concentration of the substrate which could be determined over a range of microM to mM levels. The results indicate that BLMs can be used as generic selective electrochemical transducers and as switchable biosensors to monitor rapid enzymatic reactions which alter pH.
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PMID:The bilayer lipid membrane as a generic electrochemical transducer of hydrolytic enzyme reactions. 806 May 87

A new kind of calorimetric biosensor for the measurement of the heat (molar enthalpy change) of enzymatic reactions is presented. The device operates according to the Seebeck effect, the same principle on which thermocouples are based. The thermopile used in this work consists of an array of p-type silicon/aluminium strips integrated on a thin silicon membrane (5 microns). Its sensitivity is about 1 V output voltage per watt of heating power, corresponding to a temperature resolution in the order of 10(-5) K and a heating power resolution of some tenths of a mu W in the flow system used. Furthermore, this performance is obtained without any control of external temperature because of the high common-mode thermal noise rejection ratio of the thermopile. The universal technique of calorimetry combined with the specificity of biochemical reactions makes this biosensor very versatile, with a broad range of possible applications. Glucose oxidase together with catalase for the determination of glucose, urease and penicillinase for the monitoring of urea and penicillin G, respectively, were immobilized directly onto the back side of the thermopile. The sensor was operated in conjunction with flow injection analysis which, in addition to its traditional advantages, allows preconditioning of the samples. Thus, artefacts due to mixing effects were suppressed and interference caused by differences in ionic strength between sample and carrier was strongly decreased. Detection limits between 1 and 2 mM were reported in the flow injection conditions described.
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PMID:An integrated silicon thermophile as biosensor for the thermal monitoring of glucose, urea and penicillin. 831 96


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