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)

An optimized procedure of covalent glucose oxidase, urease, Bacillus subtilis alpha-amylase and Bacillus licheniformis alpha-amylase immobilization on paramagnetic, non-porous, polyacrolein beads is presented. The resulting insolubilized enzymes can be employed for extended periods of time without loss of activity. The conditions were optimized for maximizing the activity of the linked enzyme. Coated beads bearing up to 15 micrograms active enzyme/mg(beads) were obtained on reproducible basis. The paramagnetic feature of the particles facilitates the enzyme handling. In the magnetic field, the enzyme separation is fast and complete. Thus, the paramagnetic beads represent an excellent carrier for immobilized enzymes.
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PMID:Covalent enzyme immobilization on paramagnetic polyacrolein beads. 874 90

The reference values of common blood chemistry analytes in healthy population, aged newborn to 80 years, of Rawalpindi Islamabad area were determined at AFIP, Rawalpindi. A total of 2115 healthy subjects, 1206 males and 909 females, were included in the study. Plasma glucose was analysed by GOD/POD, serum cholesterol by CHOD/PAP, triglycerides by GPO/PAP, urea by urease/GLDH, creatinine by Jaffe' rate reaction, uric acid by uricase, total bilirubin by Jendrassik and Grof, total protein by biuret, alanine transaminase (ALT) by optimized IFCC and alkaline phosphatase (AP) by optimized DGKC method. The between batch CVs of all the parameters were within acceptable quality goals. The reference values were calculated using 2.5 and 97.5 percentiles as lower and upper limits (95% CI). In healthy adult males the reference values were: fasting plasma glucose, 3.6-6.0 mmol/l; serum cholesterol; 3.2-6.6 mmol/l; triglycerides, 0.6-2.3 mmol/l; urea, 2.8-6.4 mmol/l; creatinine, 65-132 umol/l; uric acid, 164-430 umol/l; total bilirubin, 5-18 umol/l; total protein, 57-83 g/l; ALT, 15-45 U/l and AP, 185-620 U/l. The values in adult females, children and elderly subjects were slightly different than adult males. The reference values of our population show mild to moderate differences from the other Asian, European and American populations. It is recommended that reference values of different biochemical investigations should be established in various areas of Pakistan to make appropriate use of such investigations.
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PMID:Reference values of common blood chemistry analytes in healthy population of Rawalpindi-Islamabad area. 930 Nov 67

We report the results of x-ray reflectivity measurements of thin films formed by different water-soluble proteins at the air-aqueous solution interface. It is demonstrated that glucose oxidase, alcohol dehydrogenase, and urease molecules denaturate at the air-aqueous solution interface to form 8- to 14-A-thick peptide sheets. X-ray reflectivity data indicate that the spreading of a lipid monolayer at the aqueous solution surface before protein injection does not prevent proteins from unfolding. On the other hand, crosslinking of proteins results in intact enzyme layers at the subphase surface. A model that involves interaction of glucose oxidase molecules with a phospholipid monolayer is proposed. In this model, an observed decrease of the lipid electron density in the protein presence is explained in terms of "holes" in the monolayer film caused by protein molecule adsorption.
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PMID:Protein folding at the air-water interface studied with x-ray reflectivity. 1007 57

An immersible manometric sensor was made by covering the gaseous cavity of a pressure transducer with a 1 microm controlled pore membrane. Transfer of gas across the membrane allowed the pressure transducer to record changes in humidity or dissolved gas when immersed in solution. By immersing the sensor in distilled water, atmospheric humidity could be estimated by the deficit of atmospheric vapor pressure from saturation. In another application of the sensor, CO(2) was monitored continuously. This was not possible in previous closed-reactor type manometric sensors, and may allow the new technology to be used in applications requiring continuous monitoring of a process or stream. By coupling the sensor with enzymes liberating or consuming dissolved gas, different chemicals could be estimated. Urea was estimated by first hydrolyzing it with urease and then measuring the resulting CO(2) gas in solution. Glucose was measured through its enzymatic oxidation by glucose oxidase. The sensitivity to urea over the range 0-2.5 mM was about 1.02 kPa/mM, and the standard error was 0.086 mM. Due to the lower solubility of oxygen, the sensitivity to glucose in a range from 0 to 10 microM was over 100 kPa/mM, with a standard error of only 0.76 microM. This sensitivity was not possible in closed-reactor type manometric sensors due to constraints of dimensioning the head space gas volume for reproducibility and effective mass transfer. The 90% rise times for the sensor ranged from about 1-60 min for the different applications. The dynamic characteristics of the device may be improved by using a membrane with greater porosity, higher rigidity and lower thickness, and by reducing the dimensions of the cavity volume in the sensor through integrated microfabrication of the membrane onto the transducer.
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PMID:An immersible manometric sensor for measurement of humidity and enzyme mediated changes in dissolved gas. 1278 50

A microfluidic device capable of measuring real-time enthalpy changes of biochemical reactions and thermal properties of biological fluids is presented in this paper. The device consists of a freestanding microthermopile integrated with a glass microfluidic reaction chamber. The p-type polysilicon/gold microthermopiles fabricated on a 2 microm thick thermally isolated membrane showed a sensitivity of 0.94 V/W and a thermal time constant of less than 100 ms. Although the device is not restricted to enzymatic reactions, in this paper measurements of the heat of reaction from the catalytic action of glucose oxidase, catalase, and urease on glucose, hydrogen peroxide, and urea, respectively, are reported. Reactions were performed in open air using liquid batch testing and in enclosed fluidic reaction chamber by continuous flow experiments. A sensitivity of 53.5 microV/M for glucose, 26.5 microV/M for hydrogen peroxide and 17 microV/M for urea was obtained. Detection limit for glucose in the continuous flow mode is approximately 2mM (30 pmol). The aim of this work is to demonstrate the potential of the integrated calorimetric microfluidic device for fundamental thermodynamic studies in biochemical reactions. Using arrays of such devices with immobilized enzymes multi-analyte detection can be accomplished and the effects of interferents from competing substrates can be compensated. This paper presents the design, fabrication and initial testing results from such a microthermopile-based thermal biosensor.
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PMID:Calorimetric biosensors with integrated microfluidic channels. 1514 8

The principles of attenuation of the light intensity due to multiple reflections are realised in a planar silicon oxide (SiO(2))silicon nitride (Si(3)N(4)) waveguiding structure for the purpose of developing optical biosensors with improved sensitivity. The analysis of the experimental data shows that the large difference in refractive indices of core and cladding layers gives rise to an increase in sensitivity by a factor of 3 over previously reported structures. Composite polyelectrolyte self-assembled thin films containing cyclo-tetra-chromotropylene as an indicator and enzymes glucose oxidase or urease were employed in the superstrate as a sensing membrane. Individual enzyme reactions as well as their inhibition by pesticides were studied by monitoring the intensity of light output from the planar waveguide. The results were compatible with those obtained by conventional ultraviolet-visible absorption spectroscopy. The instrument detection limit for Imidacloprid pesticide was found to be as low as 10 ppb in concentration.
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PMID:Planar silicon nitride waveguides for biosensing. 1646 26

Series of liquid photopolymerizable compositions (LPhPC) based on oligouretanemetacrylate (OUM-1000T and OUM-2000T) and oligocarbonatemetacrylate (OCM-2), monomethacrylic ether of ethylene glycol and vinylpyrrolidone (VP) were tested. It was shown that the LPhPC, which contained VP (as basic hydrophylic matrix), OCM-2 (cross-linking agent) and OUM-2000T (to increase adsorption of polymer) was the most optimal. The blend contained 3 g/100 ml of enzyme. ISFET based biosensors for analysis of glucose and urea had the following characteristics: linear response in the range of concentrations 0.1-10 mmol/l, 0.05-20 mmol/l, angle of slope of concentration curve--30 mV/pC, 38 mV/pC, and response time of approximately 10-15, 5-10 min, correspondingly. The value of Km for immobilized urease and beta-glucose oxidase (GOD) achieved 0.85 and 3.1 mmol/l, respectively. It was established that under immobilization conditions at 20 degrees C the residual activity of GOD was about 35% from the initial level, the residual activity of horseradish peroxidase (HRP) and urease was 42% and 20%, respectively. In case of an immobilization of GOD at -50 degrees C its residual activity reached almost 50% from the initial level. It was investigated how different sources of UV radiation and different substances (including specific and non-specific substrates) influenced stability of the enzymes in the LPhPC and in the prepared membrane at storage. Dynamics of changes of enzyme activity at the process of photo immobilization was characterized, and requirements for enzyme maximal storage were selected. The proposed LPhPC may be prepared in advance since enzymes do not lose their activity during 2 months. Therefore, two processes, i.e. manufacturing of a transducer and preparation of a biological membrane on its surface, can be combined in one. In order to achieve this, approaches of modern electronics, such as for example photolithography, can be used. The developed LPhPC is homogenous, non-active to biological substances, permeable for the analyzed sample, can be prepared using a simple immobilization procedure, and has a defined hydrophobic-hydrophilic balance and sufficient level of adhesion to transducer surfaces. These all cover the requirements to modern biosensors.
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PMID:Liquid photopolymerizable compositions as immobilized matrix of biosensors. 1738 43

A nanostructured system composed of enzyme-functionalized silica microparticles, ca. 74 microm, and gold-coated magnetic nanoparticles, 18 +/- 3 nm, modified with pH-sensitive organic shells was used to process biochemical signals and transduce the output signal into the changes of the optoelectronic properties of the assembly. The enzymes (glucose oxidase, invertase, esterase) covalently bound to the silica microparticles performed Boolean logic operations AND/OR processing biochemical information received in the form of chemical input signals resulting in changes of the solution pH value. Dissociation state of the organic shells on the gold-coated magnetic nanoparticles was controlled by pH changes generated in situ by the enzyme logic systems. The charge variation on the organic shells upon the reversible protonation/dissociation process resulted in the changes of the gold layer localized surface plasmon resonance energy (LSPR), thus producing optical changes in the system. The proton transfer process allowed the functional coupling of the information processing enzyme systems with the signal transducing gold-coated magnetic nanoparticles providing their cooperative performance. Magnetic properties of the gold-coated magnetic nanoparticles allowed separation of the signal-transducing nanoparticles from the enzyme-modified signal processing silica microparticles. The reversible system operation was achieved by the Reset function, returning the pH value and optical properties of the system to the initial state. This process was biocatalyzed by another immobilized enzyme (urease) activated with a biochemical signal. The studied approach opens the way to novel optical biosensors logically processing multiple biochemical signals and "smart" multisignal responsive materials with logically switchable optical properties.
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PMID:Optoelectronic properties of nanostructured ensembles controlled by biomolecular logic systems. 1920 63

Application of Boolean logic operations performed by enzymes to control electrochemical systems is presented. Indium-tin oxide (ITO) electrodes with the surface modified with poly-4-vinyl pyridine (P4VP) brush were synthesized and used as switchable electrochemical systems. The switch ON and OFF of the electrode activity were achieved by pH changes generated in situ by biocatalytic reactions in the presence of enzymes used as input signals. Two logic gates operating as AND/OR Boolean functions were designed using invertase and glucose oxidase or esterase and glucose oxidase as input signals, respectively. The electrode surface coated with a shrunk P4VP polymer at neutral pH values was not electrochemically active because of the blocking effect of the polymer film. The positive outputs of the logic operations yielded a pH drop to acidic conditions, resulting in the protonation and swelling of the P4VP polymer allowing penetration of a soluble redox probe to the conducting support, thus switching the electrode activity ON. The electrode interface was reset to the initial OFF state, with the inhibited electrochemical reaction, upon in situ pH increase generated by another enzymatic reaction in the presence of urease. Logically processed biochemical inputs of various enzymes allowed reversible activation-inactivation of the electrochemical reaction.
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PMID:Switchable electrode controlled by Boolean logic gates using enzymes as input signals. 1962 18

A new format for the microtiter plate-based assays was proposed. The novelty involves the use of disk-shaped inserts for immobilization of biological and chemical reagents. The internal opening of the disks allows measurements of the reactions by standard microtiter plate readers without any additional steps involving liquid handling. Ideally the plate end-users just have to add the sample and take the measurement without any need of multiple reagent additions or transfer of the liquid to a different plate. The novel assay format also allows handling of reagents which are not soluble in an aqueous environment. As a proof of concept we describe here several model reactions which are compatible with microtiter plate format, such as monitoring enzymatic reactions catalyzed by glucose oxidase (GOx) and urease, measurements of proteins by BCA assay, analysis of pH, and concentration of antioxidants. The "mix and match" approach in the disk-shape format allows multiplexing and could be particularly useful for high throughput screening. One of the potential application areas for this novel assay format could be in a multianalyte system for measurement of clinically relevant analytes in primary care.
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PMID:Development of a new microtiter plate format for clinically relevant assays. 2226 28


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