Electron transport system assay

The following tables describe four series of assays. Series I and II characterize the substrate specificity of Keilin-Hartree particles, whereas Series III and IV employ the autoxidizable dye, methylene blue, and various inhibitors to characterize the electron-transport system in these particles. It may be practical to divide the class into groups that will only... 

Different types of organisms such as daphnia, mussels, algae, and fish have been extensively incorporated in toxicity tests for water assessment systems [65], Most of these assays are developed as test systems with few as laboratory-based sensor systems. Membranes with their active enzyme system have also been implemented in the development of toxicity kits and sensors. An example is the MitoScan Kit (Harvard BioScience, Inc., Holliston, MA), which uses fragmented inner mitochondrial membrane vesicles isolated from beef heart (EPA, 2005 [9]). The submito-chondrial particles contain complexes of enzymes responsible for electron transport and oxidative phosphorylation. When specific toxins are in the sample, the enzyme reactions are slowed or inhibited, and these are monitored spectophotometrically at 340 mn. This is still in a bioassay test kit format but may be developed to optical sensor system. 

Difference spectroscopy showed that the extract contained the hemo-proteins P-450 and cytochrome 65. Of special interest is the inhibition of 6 -hydroxylase activity by CO and the reversal of this inhibition by light, suggesting that P-450 may be involved in the reaction. In a subsequent experiment, the 6,.3-hydroxylase activity was assayed in the presence and absence of CO, and under light of various wavelengths between 400-500 m//. Reactivation of the CO inhibited enzyme was maximum at 450 mix. An action spectrum obtained from these data exhibited a maximum at 450 mu and minima at 400 and 500 m//, closely resembling the absorption spectrum of the P-450 CO complex [Voigt (62)]. It thus appears that the 6j3-hydroxylase system, like several other steroid hydroxylases, requires the participation of microsomal electron transport with P-450 as the terminal oxidase. 

Steady state levels of tigthly bound and loosely bound C-labeled nucleotides in illuminated chloroplasts were determined by the quench-centrifugation technique in an ADP regenerating hexokinase system as described (Bickel—Sand-kotter, Strotmann 1981). Photophosphorylation was assayed under the same conditions and electron transport was followed by reduction of ferricyanide (Tischer, Strotmann 1977). 

Electronic complexity reduction may provide an alternative method for sequence enrichment that is rapid, user-friendly and potentially quantitative. The device used in this experiment permits very high current densities and thus allows transport in buffers other than those typically used for electrophoresis. Beyond the use in complexity reduction, this device, with its ability to sustain high current densities, may have application in hybridization assays with a limited number of probes, immunoassays or other protein-binding reactions, and cell transport studies. Furthermore, the use of electrophoretic transport through all of the steps from sample processing through the assay should facilitate systems integration. 

In methanol, the hybrid system behaves as a reagent and can be used in automated microfluorometers to assay potassium in the range of 0-6 mM in the presence of 500-3000 fold excess of sodium (Na ) with 99% accuracy. The fluorescent chemosensor also serves as a tool for studying rates of transport of across biological membranes. A mechanism based on photo-induced electron transfer explains the observed fluorescence enhancement caused by K binding. 

The plutonium canister assay system (PCAS) determines the content of plutonium in MOX and pure oxide powders in cans contained in a specific transport container (four cans per canister) (Menlove et al. 1986). The system can be integrated into an operator s material handling system and continuous measurement cycles are performed, which are evaluated at the end of a given collection period. Thereby, continuous verification of the flow of canisters can be performed without inspectorate intervention. For inventory verification, an inspector provides an electronic list of canisters to be verified and the operator transfers the selected... 

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