An Approach to Optically Pure Bridging Chiral p-tert-Butylcalix[4]arenes through a Homologous Anionic Ortho-Fries Rearrangement.

A novel efficient approach to optically pure bridging chiral calix[4]arenes through a homologous anionic ortho-Fries rearrangement of inherently chiral calix[4]arenes was presented for the first time. As a result, two pairs of N,N'-dimethylformamidyl-substituted bridging chiral p-tert-butylcalix[4]arene enantiomers were facilely obtained. Their absolute configurations were determined through ROESY analysis, ECD comparison, and X-ray crystallographic analysis.

Virtual screening for natural product inhibitors of HIV-1 integrase.

Since there is no human homolog of this enzyme, HIV-1 integrase (IN) represents a rational and important target for treating HIV infection and preventing AIDS. The 3D structure of full-length HIV-1 IN, either separately or in complex with its inhibitors, has been lacking. Thus, scarce information about the interactions between the HIV-1 IN and its inhibitors can be referenced. To more rationally design potent HIV-1 IN inhibitors, we have previously constructed a model of the full-length HIV-1 IN tetramer and a model of the protein-viral DNA complex, as well as the pharmacophore model of HIV-1 IN strand transfer inhibitors (INSTIs). In this paper, the pharmacophore model of INSTIs was used as a 3D query to screen the Traditional Chinese Medicine Database (TCMD). The hit compounds were further filtered by Lipinski's Rule of Five and docking study to refine the retrieved hits. Finally, 9 suitable ligands with similar structures belonging to the thioglycosides were selected. Subsequent molecular dynamics simulation showed that these compounds had interactions with HIV-1 IN binding site and their possible function as IN inhibitors was discussed.

[Better performance of Western blotting: quick vs slow protein transfer, blotting membranes and the visualization methods].

OBJECTIVE: To study how the choices of the quick vs slow protein transfer, the blotting membranes and the visualization methods influence the performance of Western blotting. METHODS: The cellular proteins were abstracted from human breast cell line MDA-MB-231 for analysis with Western blotting using quick (2 h) and slow (overnight) protein transfer, different blotting membranes (nitrocellulose, PVDF and nylon membranes) and different visualization methods (ECL and DAB). RESULTS: In Western blotting with slow and quick protein transfer, the prestained marker presented more distinct bands on nitrocellulose membrane than on the nylon and PVDF membranes, and the latter also showed clear bands on the back of the membrane to very likely cause confusion, which did not occur with nitrocellulose membrane. PVDF membrane allowed slightly clearer visualization of the proteins with DAB method as compared with nitrocellulose and nylon membranes, and on the latter two membranes, quick protein transfer was likely to result in somehow irregular bands in comparison with slow protein transfer. With slow protein transfer and chemiluminescence for visualization, all the 3 membranes showed clear background, while with quick protein transfer, nylon membrane gave rise to obvious background noise but the other two membranes did not. CONCLUSIONS: Different membranes should be selected for immunoblotting according to the actual needs of the experiment. Slow transfer of the proteins onto the membranes often has better effect than quick transfer, and enhanced chemiluminescence is superior to DAB for protein visualization and allows highly specific and sensitive analysis of the protein expressions.