FeCl(3) in combination with bisphosphine ligands represents an efficient catalyst system for the cross-coupling of aryl- and alkyl thiols with aryl iodides, a broad spectrum of functional groups can be tolerated during the catalysis.

Prion diseases or transmissible spongiform encephalopathies are a rare group of fatal neurodegenerative illnesses in humans and animals caused by misfolding of prion protein (PrP). Prion protein is a cell-surface glycosylphosphatidylinositol (GPI)-anchored glycoprotein expressed mostly in the central and peripheral nervous system, and this membrane-bound protein can be cleaved from the cell membranes by phosphoinositide phospholipase C. Numerous studies have investigated GPI-free recombinant PrP, but the role of GPI on misfolding of PrP is not well known. In this study, we synthesized a GPI analog that was covalently linking to a PrP S230C mutant, resulting in S230C-GPI. The structural changes in S230C-GPI upon binding to lipid vesicles composed of mixtures of the zwitterionic lipid (POPC) and the anionic lipid (POPG) were analyzed by circular dichroism spectroscopy, and the amyloid aggregation of S230C-GPI in the liberation from phospholipid vesicles was monitored by proteinase K-digestion assay. Our results indicate that S230C-GPI in the liberation of lipid vesicles has high tendency to misfold into amyloid fibrils, while the membrane-bound S230C-GPI proteins are highly stable and rarely convert into amyloid forms. In addition, the role of cholesterol in S230C-GPI was studied. The effect of GPI, cholesterol and phospholipid vesicles on misfolding of PrP is further discussed.

Thioethers Q 0580Iron-Catalyzed Thioetherification of Thiols with Aryl Iodides. -FeCl3 combined with biphosphine ligands represents an efficient catalyst system for the cross-coupling of aryl-and alkyl thiols with aryl iodides, tolerating a broad spectrum of functional groups. -(WU, J.-R.; LIN, C.-H.; LEE*, C.-F.; Chem.

We conducted a time-dependent study of cholesterol (Ch) nucleation to investigate the effect of calcium ions in the moderate supersaturated bile. In taurocholate/lecithin (TC/L) bile at a TC to L ratio of 5.1, the presence of calcium ions enhanced the nucleation rate of Ch. Contrarily, we observed the delayed nucleation of Ch after~30 days in TC/L bile at a ratio of 2.0, regardless of the calcium ions. From the physical chemistry standpoint, the cholesterol activity (ChA T) is believed to be the driving force for Ch nucleation together with the sufficient nucleation sites. Hence, the micellar formation models along with the binding of TC monomers to calcium ions interpreted the timedependent results. Furthermore, a quasielastic light-scattering technique detected the formation of micelles and vesicles. In conclusion, the presence of calcium ions in TC/L bile at a high ratio enhances the vesicle appearance for nucleation sites and the high ChA T values for fast nucleation rate of Ch. However, an increase in the L concentration (i.e., low ratio bile) plays a significant role in the prevention of Ch gallstone formation, compared to the decrease in calcium ion concentration.