Crystallization of the Light-Harvesting Chlorophyll A/B Protein Complex from Chloroplast Membranes
Hartmut Michel in Crystallization of Membrane Proteins, 1991
The light-harvesting chlorophyll a/b protein complex of photosystem II (LHC II) is the main antenna capturing solar energy in the chloroplasts of green plants and in green algae. It occurs predominantly in stacks of closely appressed photosynthetic membranes, the chloroplast grana. Excitation energy is passed to the reaction centers of photosystems (PS) I and II which carry out the light reactions of photosynthesis. LHC II is by far the most abundant protein in chloroplast membranes1 and thus one of the most abundant membrane proteins. While several photosynthetic membrane proteins from purple bacteria (see Chapters 3, 5, 6, and 7) have been crystallized, LHC II is so far the only protein from the photosynthetic membranes of green plants to form three-dimensional crystals.
Terpenes: A Source of Novel Antimicrobials, Applications and Recent Advances
Mahendra Rai, Chistiane M. Feitosa in Eco-Friendly Biobased Products Used in Microbial Diseases, 2022
Terpenes of higher order showed increased thermotolerance. The thylakoid membrane permeability increases at higher temperatures due to increased cyclic photophosphorylation in photosystem II (Singsaas 2000). The continuous rise in temperature, the photophosphorylation system loses its ability to stop protons leaking, that resulted in a decrease of transmembrane gradient and ATP synthesis. All these events can potentially cause lowering in the Rubisco activation state due to an inhibition of RuBP regeneration (Friedman et al. 2006). They possess psychoactive effects and are used against various infectious diseases (Lewis and Haba 2019). The antimicrobial properties of some terpenoids are listed in Table 12.2. Chemical structures of some important terepenes and terpenoids (Fig. 12.1).
Overcoming Chronic and Degenerative Diseases with Energy Medicine 1
Aruna Bakhru in Nutrition and Integrative Medicine, 2018
While this might at first seem to be a preposterous idea, there is abundant supporting evidence from the literature of plant physiology. Specifically, red and blue-green algae have intricate light-absorbing structures called phycobilisomes. These “antenna” complexes contain many alpha helical regions, and are described as “light pipes” funneling excitation energy (photons) into the reaction centers of chlorophyll a of photosystem II. Chlorophyll a, in turn, is another membrane protein with five trans-membrane helices (Deisenyhofer Michel and Huber 1985). It is thought that this arrangement enables the algae to survive in weak light environments. The arrangement permits 95% efficiency of energy transfer, as reviewed by Glazer (1985). Moreover, the light sensitive pigment in the human eye, rhodopsin, is also a seven-trans-membrane-helix. Finally, there is evidence for electromagnetic fields acting as first messengers for activating cellular processes without mediation of “second messengers”
Characterization of planktonic and biofilm cells from two filamentous cyanobacteria using a shotgun proteomic approach
Published in Biofouling, 2020
Maria João Leal Romeu, Dany Domínguez-Pérez, Daniela Almeida, João Morais, Alexandre Campos, Vítor Vasconcelos, Filipe J. M. Mergulhão
Proteins related to photosystems I and II and with allophycocyanin were found in three of the four biofilm condition groups (Table 1 in dark grey shading). The specific conditions in which these proteins were identified can be found in the Supplementary material, SM5. Photosystem I (PS I, plastocyaninferredoxin oxidoreductase) and photosystem II (PS II, waterplastoquinone oxidoreductase) are multisubunit protein complexes located in the thylakoid membranes of cyanobacteria, algae and higher plants (Nelson and Yocum 2006). Although in the present study the PsaF protein was only identified in biofilms of both the cyanobacterial strains formed at 40 s−1 (Table 1), this protein is also related to photosystems (Photosystem I subunit III). A study performed by Huang et al. (2002) also identified proteins related to photosystems in the plasma membrane of Synechocystis PCC 6803. A proteomic study with different strains of M. aeruginosa showed that the majority of proteins shared among all strains were involved in photosynthesis and respiration (Alexova et al. 2011). Thus, the distribution of protein identification obtained in the present study is typical for cyanobacteria.
Erythema multiforme following exposure to the herbicide atrazine
Published in Baylor University Medical Center Proceedings, 2021
Madeline Frizzell, Nhan M. Nguyen, Sonal A. Parikh, Maya Sinai, Leonard Goldberg
Atrazine is a triazine drug, belonging to a class of nitrogen-containing heterocycles. It works by binding to plastoquinone-binding protein in photosystem II, a protein that animals lack, and thereby inhibiting the electron transport process.9 The plant dies as a result of photosynthesis inhibition.9 A study to assess the percutaneous absorption of atrazine in human skin found that 16.4% of the applied dose was absorbed, indicating its permeability potential.10 Many anticonvulsants also contain aromatic amine structures like atrazine and are well-known causes of erythema multiforme and Stevens-Johnson syndrome. Lamotrigine, phenytoin, and carbamazepine all contain aromatic amine groups, which have been more commonly related than others to the development of Stevens-Johnson syndrome and toxic epidermal necrolysis.11 However, the relationship between the aromatic amine structure and the development of these hypersensitivity disorders is not understood.11
Current knowledge about the impact of microgravity on the proteome
Published in Expert Review of Proteomics, 2019
Sebastian M. Strauch, Daniela Grimm, Thomas J. Corydon, Marcus Krüger, Johann Bauer, Michael Lebert, Petra Wise, Manfred Infanger, Peter Richter
Chen and Wang analyzed 17-day-old rice seedlings grown on Shenzhou-8 with special attention on the proteins involved in photosynthesis [58]. Compared to the ground control, from 454 differently expressed proteins identified, 38 were related to photosynthesis: 34 were downregulated, 4 were upregulated. However, the in-flight 1g control was lost and could not be compared to the µg experiment. Photosystem I (PSI) activity was more diminished than photosystem II (PSII) activity, as measured by fluorescence. This is remarkable, as under normal conditions on Earth, PSII is more sensitive to environmental factors. The results were in agreement with similar studies on the Space Shuttle [59] and RPMs [60]. Ten proteins involved in antioxidant defense in chloroplasts were upregulated, while four were downregulated.
Related Knowledge Centers
- Cofactor
- Cyanobacteria
- Electrochemical Gradient
- Enzyme
- Photosynthesis
- Plastoquinone
- Thylakoid
- Protein Complex
- Redox
- Photodissociation