Picomolar FKBP inhibitors enabled by a single water-displacing methyl group in bicyclic [4.3.1] aza-amides

Methyl groups can have profound effects in drug discovery but the underlying mechanisms are diverse and incompletely understood. Here we report the stereospecific effect of a single, solvent-exposed methyl group in bicyclic [4.3.1] aza-amides, robustly leading to a 2 to 10-fold increase in binding affinity for FK506-binding proteins (FKBPs). This resulted in the most potent and efficient FKBP ligands known to date. By a combination of co-crystal structures, isothermal titration calorimetry (ITC), density-functional theory (DFT), and 3D reference interaction site model (3D-RISM) calculations we elucidated the origin of the observed affinity boost, which was purely entropically driven and relied on the displacement of a water molecule at the protein–ligand–bulk solvent interface. The best compounds potently occupied FKBPs in cells and enhanced bone morphogenic protein (BMP) signaling. Our results show how subtle manipulation of the solvent network can be used to design atom-efficient ligands for difficult, solvent-exposed binding pockets.

Enhancement by displacement. A single methyl group displaces a water molecule from the binding site of FKBPs, resulting in the most potent binders known, outperforming the natural products FK506 and rapamycin in biochemical and cellular assays.     

Spherical Polarization Body: Synthesis of Monodisperse Micron‐Sized Polyaniline Composite Particles

A new method to synthesize uniform polyaniline‐coated composite microparticles was contrived considering the surface reactivity and porous structure of substrate polymer particles. It was found that the pore diameter together with the epoxy functional group plays a crucial role in controlling the structure of polyaniline shell. The polyaniline composite particles produced in this study are believed to find great applicability in piezoelectronics and as electro‐rheological fluids.     

Progress toward limiting generation of dendritic ethynylsilanes (PhCC)4−nMenSi (n = 0–2)

Dendritic carbosilanes based on phenylethynylmethylsilanes (PhCC)_4−nMe_nSi (n = 0–2) as cores were synthesized. The building blocks of the dendrimers consist of double bonds ( PhCCHMeSi ) in the inner shell and triple bonds [(PhCC)₂MeSi ] on the outmost periphery. The synthetic methods used the iterative alkynylation and hydrosilation cycle, which was composed of lithium phenylacethylide and dichloromethylsilane. The limiting generation of the dendrimer for the four branching type (PhCC)₄Si at a core molecule has 32 phenylethynyl groups on the third generation, 48 for the three branching type (PhCC)₃MeSi on the fourth generation, and 64 for the two branching type (PhCC)₂Me₂Si on the fifth generation. The dendrimers were characterized by the use of NMR, Maldi mass, SEC, DSC, UV as well as elemental analysis. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2749–2759, 2000