| | 1 | Author
| Ulrich Schreiber, Christof Klughammer, Christian Neubauer | Requires cookie* | | | Title
| Measuring P700 Absorbance Changes around 830 nm with a New Type of Pulse Modulation System  | | | | Abstract
| A new measuring system for monitoring absorbance changes around 830 nm is described, which was developed by modification of a commercially available pulse modulation fluorometer. All modifications concern the emitter-detector unit of the fluorometer, such that only this unit needs to be exchanged when changing from fluorescence to absorbance measurements and vice versa. The new system is shown to be well-suited for measuring redox changes of P700, the reaction center of photosystem I, in intact leaves and isolated chloroplasts. The observed kinetic changes at 830 nm in response to single turnover or multiple turnover saturating flashes are practically identical to those previously measured around 700 nm. The signal/noise ratio is sufficiently high to give well-resolved kinetics without signal averaging. When P700 is oxidized by far-red back-ground light, valuable information on the state of the intersystem electron transport chain is given by the re-reduction kinetics induced by single or multiple turnover saturating flashes. Such meas-urements are facilitated by the use of poly-furcated fiberoptics. With intact leaves, almost identi-cal responses are found when measuring through the leaf (transmission mode) or from the leaf surface (remission mode). Modulated chlorophyll fluorescence can be measured in parallel; appli-cation of saturation pulses for fluorescence quenching analysis produces transient P700 oxidation without oversaturating the measuring system. The information on the P700 redox state comple-ments that obtained from fluorescence measurements, yielding a new practical tool in plant physiological research. | | | |
Reference
| Z. Naturforsch. 43c, 686—698 (1988); received May 9 1988 | | | |
Published
| 1988 | | | |
Keywords
| P700, Chlorophyll Fluorescence, Pulse Modulation, Photosynthesis | | | |
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| default:Reihe_C/43/ZNC-1988-43c-0686.pdf | | | | Identifier
| ZNC-1988-43c-0686 | | | | Volume
| 43 | |
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