Dear All,
I want to inhibit the activity of photosystem II in the Scenedesmus obliquus and should not inhibit photosystem I.
Please suggest me the chemicals to achieve the same. And what is the lowest effective concentration?
Thank you!
Regards,
- Jayesh
Hello,
Some herbicides are effective on PSII inhibition acting on D1 proteins. For example, Düron (Dupont), Atrazin (CibaGeigy) and Bentazon (BASF). But, these chemicals block the electron transfer and directly affect the PSI since there is no electron at all at the system. For the concentrations, you can check the manuals...
The most classical inhibitor of PS2 is Diuron. Its effect can be quantified by inhibition of O2 evolution and increase of chlorophyll fluorescence (incidentally, the latter may be used as a tool for selecting resistant mutants). With Diuron, 50% inhibition is around 10 nanomolar, full inhibition is in the micromolar range (intact cells may require slightly more than isolated chloroplasts/thylakoids, depending on their permeability properties). To simplify, Diuron blocks, at plastoquinone level, electron transfer from PS2 to PS1. However, contrarily to what could be understood from the above answer, it doesn’t affect PS1: for example, cyclic photophosphorylation is preserved.
Thank you, Dr Yaroslav de Kouchkovsky,
It is clear that after inactivation of PSII there will be no electron transfer from PSII to PS I. However if I supply external electrons and protons to the microalgal biofilm, the external electrons will flow from ETC chain and perform carbon fixation? and other metabolic pathways? Thank you.
You may add an electron donor (protons come from water), but it may or may not penetrate cells and you should test before on control samples, that by itself it has no deleterious effect on CO2 fixation or cell survival.
Why do you want to use protein?? Besides, it will not enter your Scenedesmus cells!
Notice, by the way, that atrazine, mentioned in Buhara Yucesan answer, acts on the PS1 side, not PS2.
Thank You for your response. I was asking this question in a different context. Please follow this question thread for details.
https://www.researchgate.net/post/Is_there_any_protein_exists_that_blocks_Photosystem_II
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