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Justin T Ernst

Publications and source records attributed to Justin T Ernst.

6 recordsLinked to original sources
PubMed2005

Terphenyl-Based Bak BH3 alpha-helical proteomimetics as low-molecular-weight antagonists of Bcl-xL.

We describe a general method for the mimicry of one face of an alpha-helix based on a terphenyl scaffold that spatially projects functionality in a manner similar to that of two turns of an alpha-helix. The synthetic scaffold reduces the flexibility and molecular weight of the mimicked protein secondary structure. We have applied this design to the development of antagonists of the alpha-helix binding protein Bcl-x(L). Using a sequential synthetic strategy, we have prepared a library of terphenyl derivatives to mimic the helical region of the Bak BH3 domain that binds Bcl-x(L). Fluorescence polarization assays were carried out to evaluate the ability of terphenyl derivatives to displace the Bcl-x(L)-bound Bak peptide. Terphenyl 14 exhibited good in vitro affinity with a K(i) value of 0.114 muM. These terphenyl derivatives were more selective at disrupting the Bcl-x(L)/Bak over the HDM2/p53 interaction, which involves binding of the N-terminal alpha-helix of p53 to HDM2. Structural studies using NMR spectroscopy and computer-aided docking simulations suggested that the helix binding area on the surface of Bcl-x(L) is the target for the synthetic ligands. Treatment of human embryonic kidney 293 (HEK293) cells with terphenyl derivatives resulted in the disruption of the binding of Bcl-x(L) to Bax in intact cells.

Biomimetic Materials↗
PubMed2004

Protein recognition using synthetic surface-targeted agents.

The design of synthetic agents to disrupt protein-protein interactions has received relatively little attention in recent years. In this review we describe strategies for targeting different types of protein surfaces using mimetics of protein secondary or tertiary structure. In this way strong and selective binding to a protein surface has be achieved and disruption of clinically important protein-protein interactions has been demonstrated in models of human disease.

Amino Acid Sequence↗
PubMed2002

Development of a potent Bcl-x(L) antagonist based on alpha-helix mimicry.

The rational design of low-molecular weight ligands that disrupt protein-protein interactions is still a challenging goal in medicinal chemistry. Our approach to this problem involves the design of molecular scaffolds that mimic the surface functionality projected along one face of an alpha-helix. Using a terphenyl scaffold, which in a staggered conformation closely reproduces the projection of functionality on the surface of an alpha-helix, we designed mimics of the pro-apoptotic alpha-helical Bak-peptide as inhibitors of the Bak/Bcl-xL interaction. This led to the development of a potent Bcl-xL antagonist (KD = 114 nM), whose binding affinity for Bcl-xL was assessed by a fluorescence polarization assay. To determine the binding site of the developed inhibitor we used docking studies and an HSQC-NMR experiment with 15N-labeled Bcl-xL protein. These studies suggest that the inhibitor is binding in the same hydrophobic cleft as the Bak- and Bad-peptides.

Binding Sites↗
PubMed2002

XTT formazan widely used to detect cell viability inhibits HIV type 1 infection in vitro by targeting gp41.

XTT can be metabolically reduced by mitochondrial dehydrogenase in viable cells to a water-soluble formazan product. Thus XTT has been widely used to evaluate cell viability and to screen anti-HIV agents and the cytotoxicity of these agents. The present studies demonstrated that XTT formazan derived from XTT in cell culture significantly inhibits the fusion of HIV-1-infected cells with uninfected cells. Synthetic XTT formazan effectively inhibited the replication of laboratory-adapted and primary HIV-1 isolates and cell-to-cell fusion with low cytotoxicity. It blocks the six-helix bundle formation between peptides derived from the N- and C-terminal heptad repeat regions of the gp41 ectodomain (designated N- and C-peptides, respectively). Analysis by a computer-aided docking program indicates that XTT formazan may bind to the highly conserved hydrophobic pocket on the surface of the central trimeric coiled coil of gp41. These results suggest that XTT formazan inhibits HIV-1 entry by targeting the alpha-helical coiled-coil domain of gp41. This small molecular nonpeptide antiviral compound can be used as a lead for designing more effective HIV-1 entry inhibitors targeting the fusion stage of HIV-1 infection. But because XTT formazan itself has anti-HIV-1 activity, caution should be exercised when XTT is used to evaluate HIV-1 infectivity.

Animals↗