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- Glad, M, et al.
(författare)
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Separation Agent
- 1983
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Patent (populärvet., debatt m.m.)
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- Gaspar, S., et al.
(författare)
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A method for the design and study of enzyme microstructures formed by means of a flow-through microdispenser
- 2001
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 1520-6882 .- 0003-2700. ; 73:17, s. 4254-4261
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Tidskriftsartikel (refereegranskat)abstract
- Micrometer-sized enzyme grids were fabricated on gold surfaces using a novel method based on a flow-through microdispenser. The method involves dispensing very small droplets of enzyme solution (similar to 100 pL) during the concomitant relative movement of a gold substrate with respect to the nozzle of a microdispenser, resulting in enzyme patterns with a line width of similar to 100 mum. Different immobilization methods have been evaluated, yielding either enzyme monolayers using functionalized self-assembled thiol monolayers for covalent binding of the enzyme or enzyme multilayers by cross-linking or entrapping the enzymes in a polymer film. The latter immobilization techniques allow the formation of coupled multienzyme structures. On the basis of this feature, coupled bienzyme (glucose oxidase and catalase) or three-enzyme (alpha -glucosidase, mutarotase, and glucose oxidase) microstructures consisting of line patterns of one enzyme intersecting with the patterned lines of the other enzyme(s) were fabricated. By means of scanning electrochemical microscopy (SECM) operated in the generator-collector mode, the enzyme microstructures and their integrity were visualized using the localized detection of enzymatically produced/consumed H2O2. A calibration curve for glucose could be obtained by subsequent SECM line scans over a glucose oxidase microstructure for increasing glucose concentrations, demonstrating the possibility of obtaining localized quantitative data from the prepared microstructures. Possible applications of these enzyme microstructures for multianalyte detection and interference elimination and for screening of different biosensor configurations are highlighted.
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- Lindbladh, C, et al.
(författare)
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Preparation and kinetic characterization of a fusion protein of yeast mitochondrial citrate synthase and malate dehydrogenase
- 1994
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 33:39, s. 8-11692
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Tidskriftsartikel (refereegranskat)abstract
- We have expressed the DNA of the fusion of CS1 to MDH1 in Escherichia coli gltA-. The fusion protein (CS1/MDH1) is the C-terminus of CS1 linked in-frame to the N-terminus of MDH1 with a short linker of glycyl-seryl-glycyl. The fusion protein produced was isolated and purified. Gel filtration studies indicated that CS1/MDH1 had a M(r) of approximately 170,000. Western blotting analysis with SDS gel indicated a M(r) of approximately 90,000-95,000 (theoretical M(r) = 87,000). This is the expected M(r) for the fusion protein subunit. The kinetics of CS1 and MDH1 activities of the fusion protein were compared to those of the free enzymes. In addition, the effect of AAT reaction, as a competitor for the intermediate OAA of the coupled MDH-CS reaction, was examined. It was observed that AAT was a less effective competitor for OAA when the CS1/MDH1 fusion protein is used than when the separate enzymes are employed. In addition, the transient time for the coupled reaction sequence was less for the fusion protein than for the free enzymes.
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- Mikeladze, E, et al.
(författare)
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Redox hydrogel-based bienzyme microelectrodes for amperometric monitoring of L-glutamate
- 2002
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Ingår i: Electroanalysis. - 1040-0397. ; 14:6, s. 393-399
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Tidskriftsartikel (refereegranskat)abstract
- Fabrication and characterization of amperometric bienzyme L-glutamate sensitive microelectrodes are the prerequisite for monitoring changes Of L-glutamate concentration at glutamate-secreting cell cultures. The design of the glutamate microelectrodes is based on incorporating L-glutamate oxidase and horseradish peroxidase into a redox-hydrogel containing PVI19-dmeOs as the redox mediator and immobilizing this system onto the surface of platinum microdisk electrodes using, a dip-coating procedure. For amperometric measurements Of L-glutamate, these redox hydrogel-based bienzyme microelectrodes can be operated at low working potentials (-50 mV vs. Ag/AgCl) decreasing the influence of electroactive interferants possibly present in biological samples. The L-glutamate microsensors are characterized by a good operation stability and sensitivity (0.038+/-0.005 mAM(-1)), a low detection limit (0.5 muM in a conventional amperometric set-up and 0.03 muM in a Faraday cage, defined as three times the signal-to-noise ratio), a linear range up to 50 muM and a response time of about 35 s. The glutamate biosensors have been applied for the direct measurement Of L-glutamate release (upon chemical stimulation) from a population of immortalized hippocampal neurons (HN10 cells) demonstrating the possibility to amperometrically monitor in-Situ L-glutamate secretion from these cells.
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