Browsing by Author "Vohidov, Farrukh"

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    Dirhodium Metallopeptides for Catalytic Protein Modification & Inhibition of Protein-Protein Interactions
    (2016-06-03) Vohidov, Farrukh; Ball, Zachary T
    The fundamental goal of chemical biology is to develop tools for interrogation of the activity and function of biomolecules, ultimately leading to understanding of the inner workings of biological systems. This thesis discusses three contributions towards expanding the chemical biology toolbox: i) an enzyme-like specific protein modification method, ii) a chemical blotting protocol for analyzing the products of protein modification reactions, iii) potent and selective inhibitors of protein-protein interactions. Inspired by the exquisite control and selectivity seen in enzymatic transformations, dirhodium metallopeptides were developed that catalyze selective labeling of natural proteins in their native environment. These tailored metallopeptides are highly specific for the targeted proteins, allowing quantitative modification of a target protein at micromolar concentrations even in the presence of a large number of potentially reactive biomolecules. The utility of the method for biophysical studies was demonstrated by labeling Yes protein kinase directly in cell lysate. In order to analyze products of in-lysate modification reactions, a chemical blotting protocol was established, and luminogenic probes were designed for use in chemical blotting and cell imaging applications. Design of inhibitors for protein-protein interactions is a formidable challenge due to the structural and chemical properties of protein interfaces involved in these interactions. Exploiting the potential of the dirhodium core to participate in cooperative binding, inhibitors for SH3 protein domains were developed by attaching dirhodium at different positions on a parent peptide ligand with modest SH3-affinity. The rationally designed library of dirhodium metalloinhibitors yielded the tightest known inhibitor for Lyn SH3; Lyn, a tyrosine kinase, represents an important target to further our understanding of a variety of cellular dysfunctions. Taken together, these contributions represent a set of powerful tools in chemical biology and can serve as a foundation for continued advancement of the field.
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    Luminogenic iridium azide complexes
    (Royal Society of Chemistry, 2015) Ohata, Jun; Vohidov, Farrukh; Aliyan, Amirhossein; Huang, Kewei; Martí, Angel A.; Ball, Zachary T.
    The synthesis and characterization of luminogenic, bioorthogonal iridium probes is described. These probes exhibit long photoluminescence lifetimes amenable to time-resolved applications. A simple, modular synthesis via 5-azidophenanthroline allows structural variation and allows optimization of cell labeling.
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    Potent and selective inhibition of SH3 domains with dirhodium metalloinhibitors
    (Royal Society of Chemistry, 2015) Vohidov, Farrukh; Knudsen, Sarah E.; Leonard, Paul G.; Ohata, Jun; Wheadon, Michael J.; Popp, Brian V.; Ladbury, John E.; Ball, Zachary T.
    Src-family kinases (SFKs) play important roles in human biology and are key drug targets as well. However, achieving selective inhibition of individual Src-family kinases is challenging due to the high similarity within the protein family. We describe rhodium(II) conjugates that deliver both potent and selective inhibition of Src-family SH3 domains. Rhodium(II) conjugates offer dramatic affinity enhancements due to interactions with specific and unique Lewis-basic histidine residues near the SH3 binding interface, allowing predictable, structure-guided inhibition of SH3 targets that are recalcitrant to traditional inhibitors. In one example, a simple metallopeptide binds the Lyn SH3 domain with 6 nM affinity and exhibits functional activation of Lyn kinase under biologically relevant concentrations (EC50 200 nM).
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    Rhodium(II) Proximity-Labeling Identifies a Novel Target Site on STAT3 for Inhibitors with Potent Anti-Leukemia Activity
    (Wiley, 2015) Minus, Matthew B.; Liu, Wei; Vohidov, Farrukh; Kasembeli, Moses M.; Long, Xin; Krueger, Michael; Stevens, Alexandra; Kolosov, Mikhail I.; Tweardy, David J.; Sison, Edward Allen R.; Redell, Michele S.; Ball, Zachary T.
    Nearly 40 % of children with acute myeloid leukemia (AML) suffer relapse arising from chemoresistance, often involving upregulation of the oncoprotein STAT3 (signal transducer and activator of transcription 3). Herein, rhodium(II)-catalyzed, proximity-driven modification identifies the STAT3 coiled-coil domain (CCD) as a novel ligand-binding site, and we describe a new naphthalene sulfonamide inhibitor that targets the CCD, blocks STAT3 function, and halts its disease-promoting effects in vitro, in tumor growth models, and in a leukemia mouse model, validating this new therapeutic target for resistant AML.