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The Effect of Polyene Antibiotics on Photosynthetic Electron Transfer
D. G. BISHOP
Journal of Experimental Botany
Vol. 25, No. 86 (June 1974), pp. 491-502
Published by: Oxford University Press
Stable URL: http://www.jstor.org/stable/23688662
Page Count: 12
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The effect of four polyene antibiotics and digitonin on photosynthetic electron transfer by maize mesophyll chloroplasts has been investigated. All five compounds, at concentrations between 0.1 mM and 2.0 mM, inhibited photosystem 2 activity as measured by the photoreduction of ferricyanide and 2,6-dichlorophenolindophenol from water. Etruscomycin, amphotericin B, and digitonin were more inhibitory than filipin and nystatin. Photosystem 1 activity was inhibited by 1 mM concentrations of etruscomycin, amphotericin B, and digitonin but not by filipin and nystatin. In all cases where inhibition occurred, it was temperature dependent. The inhibition of photosystem 1 activity could be relieved by plastocyanin. Etruscomycin and digitonin, at concentrations of 0.5 mM and above, caused disintegration of the chloroplasts, and this disintegration was accompanied by a two- to three-fold increase in photosystem 1 activity in the presence of plastocyanin. It is concluded that the action of polyene antibiotics results in the release of plastocyanin from its site in the photosynthetic electron transfer chain. The results are discussed in terms of the abilities of polyene antibiotics and digitonin to form complexes with sterols.
Journal of Experimental Botany © 1974 Oxford University Press