The oxygen-evolving complex is the site of water oxidation. The central part of PSII is designated as PSII reaction center (RC) or PSII core or simply PSII, which binds all of the electron transfer cofactors and performs light-induced charge separation, electron transfer and water oxidation reactions. The four xanthophylls are shown: N1 (neoxanthin), L1 and L2 (luteins), and V1 (violaxanthin). In vivo, two PSII reaction center complexes form the dimeric PSII core complex, which may bind up to four trimeric LHCII and six monomeric CP24, CP26, and CP29. LHCII in green algae and higher plants exists in trimeric and monomeric forms (Liu et al., 2004; Su et al., 2017), and maximally three LHCII trimers and two LHCII monomers are found in a green algal PSII-LHCII supercomplex (Shen et al., 2019). 8). Lhcb1, Lhcb2, and Lhcb3 associate in different combinations to form a population of heterotrimeric LHCII, which show different strengths of binding to the PSII core complex. Among these are at least five TPR proteins, most of which interact with or impinge on the D1 protein of the PSII reaction center (Table 3). 1. Hence, the efficiency of light harvesting in PSII is determined by the number of LHCII subunits, the pigment order within them, the interaction between subunits, and their closeness to the reaction center complex. The experimental evidence that oxygen is released through cyclic reaction of oxygen evolving complex (OEC) within one PSII was provided by Pierre Joliot et al. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. URL: https://www.sciencedirect.com/science/article/pii/B9780128096338214040, URL: https://www.sciencedirect.com/science/article/pii/S0076687918304166, URL: https://www.sciencedirect.com/science/article/pii/B9780128194607000128, URL: https://www.sciencedirect.com/science/article/pii/S0076687915000245, URL: https://www.sciencedirect.com/science/article/pii/B9780123708731000319, URL: https://www.sciencedirect.com/science/article/pii/S193764481600006X, URL: https://www.sciencedirect.com/science/article/pii/B978012384986100003X, URL: https://www.sciencedirect.com/science/article/pii/B9780123786302001651, URL: https://www.sciencedirect.com/science/article/pii/B9780128018545000108, Photosystem II: Assembly and Turnover of the Reaction Center D1 Protein in Plant Chloroplasts☆. Two types of LHCII trimers are shown – strongly bound S-trimers of Lhcb1, Lhcb2 and more weakly bound M-trimers containing Lhcb3. [1] DCMU is a chemical often used in laboratory settings to inhibit photosynthesis. The center of the PS II complex is a heterodimer consisting of the subunits D1 and D2 with six chl-a, two pheophytin, two plastoquinone, and one to two carotenoid molecules bound to it. Vitally important components of both photosystems are the light-harvesting antennae, the light-collecting units (mainly LHCI and LHCII for PSI and PSII, respectively) that ensure high rates of energy input into the photosynthetic reaction centers (RCI and RCII, respectively) by intercepting large numbers of light quanta of various energies/colors. Both are required for interaction with its cognate binding partners, the inner antenna proteins CP43 and CP47, probably during PSII assembly/reassembly (Bhuiyan et al., 2015). c. Where does the Calvin cycle occur? Photosystem II (or water-plastoquinone oxidoreductase) is the first protein complex in the light-dependent reactions of oxygenic photosynthesis. There are two types of photosystems photosystem I (PS I) and photosystem II (PS Il). C. Water molecules enter the thylakoid membrane and are split. Ongoing system to fill the 2 electrons needed for NADP+. The composition of PSII is even more complex than that of PSI, with at least 20 protein subunits and 77 cofactors which have to be assembled in a coordinated manner (Komenda et al., 2012; Nickelsen and Rengstl, 2013). Light energy (indicated by wavy arrows) absorbed by photosystem II causes the formation of high-energy electrons, which are transferred along a series of acceptor molecules in an electron transport chain to photosystem I. Photosystem II obtains replacement electrons from water molecules, resulting in their split into hydrogen ions (H+) and oxygen atoms. The subunits O, P, Q stabilize the Mn cluster. Photosystem II: Protein Components, Structure and Electron Transfer☆, Membrane Proteins—Engineering, Purification and Crystallization, International Review of Cell and Molecular Biology, Komenda et al., 2012; Nickelsen and Rengstl, 2013, Diner et al., 1988; Roose and Pakrasi, 2004, Nickelsen and Rengstl, 2013; Rast et al., 2015, Photosynthesis is an electron transport process, Dynamic Behavior of Photosystem II Light Harvesting, Encyclopedia of Biological Chemistry (Second Edition), Halophytes for Food Security in Dry Lands, Biochimica et Biophysica Acta (BBA) - Bioenergetics, Core-antenna, binds peripheral antennae LHC, Binds heme, protection of PS II against light damage. The first function is mediated via its extended C-terminus, whereas the latter requires the TPR domain–both of which are proposed to be oriented towards the stromal side of the thylakoid membrane (Dewez et al., 2009). What happens in the photosystem 2 when it is hit by a photo of light What happens in the photosystem 2 when it is hit by a photo of light Answers: 2 Get Other questions on the subject: Biology.