Crystal structures of Lymnaea stagnalis AChBP in complex with neonicotinoid insecticides imidacloprid and clothianidin

Neonicotinoid insecticides, which act on nicotinic acetylcholine receptors (nAChRs) in a variety of ways, have extremely low mammalian toxicity, yet the molecular basis of such actions is poorly understood. To elucidate the molecular basis for nAChR–neonicotinoid interactions, a surrogate protein, acetylcholine binding protein from Lymnaea stagnalis (Ls-AChBP) was crystallized in complex with neonicotinoid insecticides imidacloprid (IMI) or clothianidin (CTD). The crystal structures suggested that the guanidine moiety of IMI and CTD stacks with Tyr185, while the nitro group of IMI but not of CTD makes a hydrogen bond with Gln55. IMI showed higher binding affinity for Ls-AChBP than that of CTD, consistent with weaker CH–π interactions in the Ls-AChBP–CTD complex than in the Ls-AChBP–IMI complex and the lack of the nitro group-Gln55 hydrogen bond in CTD. Yet, the NH at position 1 of CTD makes a hydrogen bond with the backbone carbonyl of Trp143, offering an explanation for the diverse actions of neonicotinoids on nAChRs

Effects of Mild Baking on Hydrogen Removal from the Modified Surface of the First Wall in the LHD

An additional deuterium irradiation was performed for long-term samples mounted on the first wall in the large helical device (LHD) to investigate the effect of mild baking (at 368 K) on fuel hydrogen removal from the modified surface. The efficiency of baking strongly depended on the surface conditions. In the erosion dominant area, almost all the retained deuterium was removed by baking, whereas only 17% and 13% of the retained deuterium were removed from the boron and carbon deposition areas, respectively. The results suggest that the erosion dominant area in the first wall can act as a pumping wall during the main discharge, and, in contrast, the fuel hydrogen retention can continuously increase in boron and carbon deposition areas owing to the low removal efficiency of fuel hydrogen given that the deposition continues during the plasma discharge

Crystallization and preliminary X-ray diffraction studies of the ferredoxin reductase component in the Rieske nonhaem iron oxygenase system carbazole 1,9a-dioxygenase

The NAD(P)H:ferredoxin oxidoreductase in carbazole 1,9a-dioxygenase from Janthinobacterium sp. J3 was crystallized and diffraction data were collected to 2.60 Å resolution