A high-throughput screen for identification of molecular mimics of Smac/DIABLO utilizing a fluorescence polarization assay.

Resistance to apoptosis is afforded by inhibitor of apoptosis proteins (IAPs) which bind to and inhibit the caspases responsible for cleavage of substrates leading to apoptotic cell death. Smac (or DIABLO), a proapoptotic protein released from the mitochondrial intermembrane space into the cytosol, promotes apoptosis by binding to IAPs, thus reversing their inhibitory effects on caspases. We have developed a high-throughput fluorescence polarization assay utilizing a fluorescein-labeled peptide similar to the "IAP binding" domain of Smac N terminus complexed with the BIR3 domain of X-linked IAP (XIAP) to identify small-molecule mimics of the action of Smac.

Molecular targeting of inhibitor of apoptosis proteins based on small molecule mimics of natural binding partners.

An assay based on a solvent-sensitive fluorogenic dye molecule, badan, is used to test the binding affinity of a library of tetrapeptide molecules for the BIR3 (baculovirus IAP repeat) domain of XIAP (X-linked inhibitor of apoptosis protein). The fluorophore is attached to a tetrapeptide, Ala-Val-Pro-Cys-NH(2), through a thiol linkage and, upon binding to XIAP, undergoes a solvatochromic shift in fluorescence emission. When a molecule (e.

Ruthenium(II) Complexes of 2-Aryl-1,10-phenanthrolines: Synthesis, Structure, and Photophysical Properties.

The synthesis, characterization, and photochemical investigation of a series of Ru(II) complexes having 2-phenyl- and 2,9-diphenyl substituted phenanthroline ligands are reported. Structural characterization of some of the complexes revealed that the phenyl substituents of the phenanthroline ligand are oriented nearly perpendicular to the phenanthroline ring and pi-stack with adjacent coordinated 2,2'-bipyridyl ligands. Most of the complexes are nonluminescent at room temperature, and temperature-dependent luminescence studies suggest nonradiative relaxation in solution is dominated by rapid thermally activated internal conversion from the initially populated (3)MLCT state to a ligand field (LF) state which decays rapidly to the ground state.