| Abstrakt: |
Studies of the components and role of redox activity at the plasmalemma are dependent on the use of sensitive assay procedures. Many methods have been developed to measure redox activity, but special problems arise when the plasmalemma is the focus of the investigation. In this review, the methods and probes for analyzing electron transport at the plasmalemma are critically evaluated. Determinations of hydrogen peroxide are also included, although no firm evidence exists that the appearance of this substance is dependent on transplasmalemma electron transport. Procedures include those based on light absorption (spectrophotometric) and electrical changes (polarographic, potentiometric, amperometric/coulometric), as well as those dependent on radioactive, fluorescent, light emitting and electron spin resonance probes. The estimation of proton fluxes in the presence of redox probes is also considered. It is concluded that measurements of redox activity at the plasmalemma can be performed on tissues, cells, membrane vesicles and solubilized preparations, but no one procedure is ideal; furthermore, care must be taken to insure that the probes themselves are not altering the system being studied. [ABSTRACT FROM AUTHOR] |
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