Biosynthesis of unnatural glycolipids possessing diyne moiety in the acyl chain in the green sulfur photosynthetic bacterium Chlorobaculum tepidum grown by supplementation of 10,12-heptadecadiynic acid

AbstractUnnatural glycolipids possessing the diyne moiety in their acyl groups were successfully biosynthesized in the green sulfur photosynthetic bacterium Chlorobaculum (Cba.) tepidum by cultivation with supplementation of 10,12-heptadecadiynic acid. Monogalactosyldiacylglycerol (MGDG) and rhamnosylgalactosyldiacylglycerol (RGDG) esterified with one 10,12-heptadecadiynic acid were primarily formed in the cells, and small amounts of glycolipids esterified with the two unnatural fatty acids can also be detected. The relative ratio of these unnatural glycolipids occupied in the total glycolipids was estimated to be 49% based on HPLC analysis using a evaporative light scattering detector. These results indicate that the acyl groups in glycolipids, which play important roles in the formation of extramembranous antenna complexes called chlorosomes, can be modified in vivo by cultivation of green sulfur photosynthetic bacteria with exogenous synthetic fatty acids. Visible absorption and circular dichroism spectra of Cba. tepidum containing the unnatural glycolipids demonstrated the formation of chlorosomes, indicating that the unnatural glycolipids in this study did not interfere with the biogenesis of chlorosomes

Synthesis of self-aggregative zinc chlorophylls possessing polymerizable esters as a atable model compound for main light-harvesting antennas of green photosynthetic bacteria

Zinc bacteriochlorophyll-d derivatives possessing a polymerizable moiety at the 17-propionate were prepared as model compounds of natural occurring chlorophylls in the main peripheral antennas of green photosynthetic bacteria (chlorosomes). The synthetic compounds self-aggregated in nonpolar organic solvents as well as in the solid state to give large oligomers similar to chlorosomal J-aggregates. Such introduction of the polymerizable groups in the ester did not suppress the ability of self-aggregation

Photoinduced Catalytic Organic-Hydride Transfer to CO₂ Mediated with Ruthenium Complexes as NAD⁺/NADH Redox Couple Models

ルテニウム錯体を触媒とする有機ヒドリドを介した二酸化炭素光還元 --新たな人工光合成系の創製に向けて--. 京都大学プレスリリース. 2023-02-07.The catalytic organic-hydride transfer to CO2 was first achieved through the photoinduced two-electron reduction of the [Ru(bpy)2(pbn)]²⁺/[Ru(bpy)2(pbnHH)]²⁺ (bpy=2, 2'-bipyridine, pbn=2-(pyridin-2-yl)benzo[b]-1, 5-naphthyridine, and pbnHH=2-(pyridin-2-yl)-5, 10-dihydrobenzo[b]-1, 5-naphthyridine) redox couple in the presence of 1, 3-dimethyl-2-phenyl-2, 3-dihydro-1H-benzo[d]imidazole (BIH). The active species for the catalytic hydride transfer to carbon dioxide giving formate is [Ru(bpy)(bpy⋅−)(pbnHH)]+ formed by one-electron reduction of [Ru(bpy)2(pbnHH)]²⁺ with BI⋅