Title
Size Selectivity in the Hydroxylation of Esters of Unsaturated Fatty Acids
Author
Ugo Azzena, Massimo Carraro, Luisa Pisano, Elisa Pintus, Salvatore Pintus, Riccardo Polese, Pierpaolo Satta, Silvia Gaspa, Lidia De Luca, Alessandro Taras, Sebastiano Garroni
Year
2022
Journal
European Journal of Lipod science and technology
Abstract
Photosystem I (PSI) is one of the two photosystems functioning in light-energy harvesting, transfer, and electron transfer in photosynthesis. However, the oligomerization state of PSI is variable among photosynthetic organisms. We present a 3.8-Å resolution cryo-electron microscopic structure of tetrameric PSI isolated from the glaucophyte alga Cyanophora paradoxa, which reveals differences with PSI from other organisms in subunit composition and organization. The PSI tetramer is organized in a dimer of dimers with a C2 symmetry. Unlike cyanobacterial PSI tetramers, two of the four monomers are rotated around 90°, resulting in a completely different pattern of monomer-monomer interactions. Excitation-energy transfer among chlorophylls differs significantly between Cyanophora and cyanobacterial PSI tetramers. These structural and spectroscopic features reveal characteristic interactions and excitation-energy transfer in the Cyanophora PSI tetramer, suggesting that the Cyanophora PSI could represent a turning point in the evolution of PSI from prokaryotes to eukaryotes.
Instrument
FT/IR-4600
Keywords
kinetics, Dowex 50WX2,