Inhibitory activities of anthraquinones from Rubia akane on phosphatase regenerating liver-3.

The methanolic extract of the roots of Rubia akane (Rubiaceae) was found to show inhibitory activity on phosphatase of regenerating liver-3 (PRL-3). Bioassay-guided fractionation of the methanolic extract resulted in the isolation of two anthraquinone compounds, 2-methyl-1,3,6-trihydroxy-9,10-anthraquinone-3-O-(6'-O-acetyl)-α-rhamnosyl(1→2)-β-glucoside and 2-methyl-1,3,6-trihydroxy-9,10-anthraquinone, as inhibitors on PRL-3. These compounds inhibited PRL-3 in a dose-dependent manner with IC₅₀ values of 5.

Detection of conformationally changed MBP using intramolecular FRET.

The principal objective of this study was to explore protein conformational changes using fluorescence resonance energy transfer (FRET) technology. Maltose binding protein (MBP) was adopted as a target model, due to its well-characterized structure and ligand specificity. To the best of our knowledge, this is the first report to provide information regarding the biological distance between the two lobes of MBP upon maltose binding.