Phys.org April 5, 2023 Carboxysomes are proteinaceous bacterial microcompartments that sequester the key enzymes for carbon fixation in cyanobacteria and some proteobacteria. Despite their significance in carbon fixation and great bioengineering potentials, the structural understanding of native carboxysomes is currently limited to low-resolution studies. An international team of researchers (UK, Germany, Austria) has characterized a native α-carboxysome from a marine cyanobacterium by single-particle cryoelectron microscopy. They have determined the structure of its RuBisCO enzyme, and obtained low-resolution maps of its icosahedral shell, and its concentric interior organization. They proposed a complete atomic model of an intact carboxysome, providing insight into […]
Tag Archives: photosynthesis
Photosynthesis ‘hack’ could lead to new ways of generating renewable energy
Science Daily March 22, 2023 Previous approaches to ‘re-wire’ photosynthesis for higher biomass-conversion efficiencies and new reaction pathways have focused on charge extraction at terminal electron acceptors of the photosystems. Electron extraction at earlier steps, perhaps immediately from photoexcited reaction centres, would enable greater thermodynamic gains. Using in vivo ultrafast transient absorption (TA) spectroscopy an international team of researchers (UK, Finland, Germany) demonstrated the extraction of electrons directly from photoexcited PSI and PSII at early points (several picoseconds post-photo-excitation) with live cyanobacterial cells or isolated photosystems, and exogenous electron mediators. They postulated that these mediators oxidize peripheral chlorophyll pigments participating […]
Recreating the natural light-harvesting nanorings in photosynthetic bacteria
Science Daily January 31, 2023 Photosynthesis in plants and some bacteria relies on light-harvesting (LH) supramolecules which come in different structures. So far, these LH molecules have not been artificially prepared. Researchers in Japan demonstrated that mixing a chlorophyll derivative with naphthalenediamide in an organic solvent leads to the formation of dimers that spontaneously self-assembled into ring-shaped structures, each several hundred nanometers in diameter. They observed that chlorophyll dimers, molecules composed of two chlorophyll units linked by naphthalene, initially self-assembled into stable wavy nanofibers. Upon heating these nanofibers at 50°C, they disassembled into smaller nanoring precursors whose ends eventually joined […]
Glass-like shells of diatoms help turn light into energy in dim conditions
Nanowerk November 22, 2022 Using a toolkit consisting of numerical models and four microscopy techniques, researchers in Canada evaluated the optical response of frustules belonging to the species Nitzschia filiformis. Localized regions of the frustule exhibited functionalities including diffraction, lensing, waveguiding, circulation, filtering, resonances, and dispersion control. They showed that these functionalities are complementary to each other in contributing to the solar energy harvesting mechanisms of capture, redistribution, and retention. In this context, frustule performance was enhanced by perturbations to its sub-wavelength structure. According to the researchers their finding provides quantitative support to the hypothesis that the frustule enhances photosynthesis […]
This hydrogen fuel machine could be the ultimate guide to self-improvement
Science Daily April 5, 2021 Development of an efficient and durable photoelectrode is important for the deployment of solar-fuel production. A team of researchers in the US (Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory, University of Michigan) has shown the photoelectrochemically self-improving behaviour of a silicon/gallium nitride photocathode for hydrogen production with efficiency approaching ~100%. Using correlative approach based on different spectroscopic and microscopic techniques, and density functional theory calculations, they provided a mechanistic understanding of the chemical transformation as the origin of the self-improving behaviour. A thin layer of gallium oxynitride forms on the side walls of the […]
Photosynthetic protein structure that harvests and traps infrared light
Phys.org April 4, 2018 Plants and algae use chlorophyll to absorb energy from the Sun to power photosynthesis at wavelengths up to 720 nm. Researchers in the UK studied photosynthetic LH1-RC complex from the bacterium Blastochloris viridis, which can harvest and use light at wavelengths over 1,000 nm. They showed how it converts near-infrared light into an electrical charge to power cell metabolism, which enables the bacterium to live at the extreme red limit of photosynthesis on Earth. The study gives an insight into the efficiency and limits of photosynthesis… read more. TECHNICAL ARTICLE