Inhibition of photosynthetic electron transport by amphotericin B

By assaying partial reactions of the photosynthetic electron transport system using thylakoids from spinach as well as from the algae Bumilleriopsis, Dunaliella , and Anabaena , it was demonstrated that the polyene antibiotic amphotericin B has no specific effect on plastocyanin. Pretreating spinach and algal thylakoids with this antibiotic decreased photosystem‐II as well as photosystem‐I activity regardless of whether the membranes contained plastocyanin or cytochrome c‐553. Different sensitivity of cell‐free electron transport activity against this antibiotic was observed due to the species used. With Dunaliella , the photosystem‐II region was inhibited more strongly than photosystem‐I, while Bumilleriopsis chloroplasts – although not containing plastocyanin – exhibited a stronger inhibition of the photosystem‐I region. Apparently, amphotericin B mainly solubilizes redox compounds that form connecting pools in the photosynthetic electron transport chain.