Photosynthetic complexes (PSII/PSI)

Photosynthetic complexes are massive multi-subunit pigment-protein assemblies found in the thylakoid membranes of plants, algae, and cyanobacteria. The primary components, Photosystem II (PSII) and Photosystem I (PSI), work in series to capture solar energy and convert it into chemical energy (ATP and NADPH) through a process known as the Z-scheme of electron transport (https://www.ncbi.nlm.nih.gov/books/NBK21191/). PSII facilitates the light-driven splitting of water into oxygen and protons, providing the initial electrons for the chain, while PSI facilitates the final reduction of NADP+. While these complexes are not therapeutic targets in humans because mammals lack photosynthetic machinery, they are the primary targets for a wide array of commercial herbicides which disrupt electron flow to induce oxidative stress and plant death (https://pmc.ncbi.nlm.nih.gov/articles/PMC7432543/). Research into these complexes is also vital for the development of bio-hybrid solar cells and understanding the mechanisms of photodynamic therapy, where chlorophyll-like pigments are used to generate reactive oxygen species for treating cancers (https://pubmed.ncbi.nlm.nih.gov/22423985/).

Other names

Photosystem II (PSII)Photosystem I (PSI)Light-harvesting complex (LHC)Chloroplastic electron transport chainWater-plastoquinone oxidoreductasePlastocyanin-ferredoxin oxidoreductase

Inhibition of the photosynthetic electron transport chain, most commonly by binding to the QB-binding site on the D1 protein of Photosystem II, which blocks the transfer of electrons to plastoquinone.