- Activity-Based Probes for Isoenzyme- and Site-Specific Functional Characterization of Glutathione S-Transferases
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Glutathione S-transferases (GSTs) comprise a diverse family of phase II drug metabolizing enzymes whose shared function is the conjugation of reduced glutathione (GSH) to endo- and xenobiotics. Although the conglomerate activity of these enzymes can be measured, the isoform-specific contribution to the metabolism of xenobiotics in complex biological samples has not been possible. We have developed two activity-based probes (ABPs) that characterize active GSTs in mammalian tissues. The GST active site is composed of a GSH binding "G site" and a substrate binding "H site". Therefore, we developed (1) a GSH-based photoaffinity probe (GSTABP-G) to target the "G site", and (2) an ABP designed to mimic a substrate molecule and have "H site" activity (GSTABP-H). The GSTABP-G features a photoreactive moiety for UV-induced covalent binding to GSTs and GSH-binding enzymes. The GSTABP-H is a derivative of a known mechanism-based GST inhibitor that binds within the active site and inhibits GST activity. Validation of probe targets and "G" and "H" site specificity was carried out using a series of competition experiments in the liver. Herein, we present robust tools for the characterization of enzyme- and active site-specific GST activity in mammalian model systems.
- Stoddard, Ethan G.,Killinger, Bryan J.,Nair, Reji N.,Sadler, Natalie C.,Volk, Regan F.,Purvine, Samuel O.,Shukla, Anil K.,Smith, Jordan N.,Wright, Aaron T.
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- Electron donor-acceptor complexes of 2,3-dichloro-5-nitro-1,4- naphthoquinone with some methyl substituted anilines: Formation of 1:2 (A:D) complexes
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The donor-acceptor complexes between 2,3-dichloro-5-nitro-1,4- naphthoquinone (DClNNQ) and some methyl substituted anilines were investigated by spectrophotometric method. This investigation was carried out in three different chlorinated solvents viz., chloroform, dichloromethane and 1,2-dichloroethane. Experimental evidences shows the formation of 1:2 (A:D) complexes but not 1:1 complexes. The calculated values of the oscillator strength and transition moment confirms this suggestion. The stoichiometry of the complexes was unaffected by the variation of temperature over a small interval and also change in solvent. The thermodynamic and spectroscopic parameters were evaluated in all the three solvents for the formation of CT-complexes. The influence of used solvents on the thermodynamic and spectroscopic parameters was investigated. The strength of the donors was also investigated.
- Neelgund, Gururaj M.,Budni
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- Identification of compounds for the treatment or prevention of proliferative diseases
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The invention features compounds for the treatment of cancer and other proliferative diseases. These compounds were identified in screening assays that contact candidate compounds with a cell containing a nucleic acid that includes a HER2 regulatory element and a reporter sequence. The invention further features compounds structurally related to those identified by the screening assays. Finally, the invention features methods of treating or preventing a proliferative disease using the compounds of the invention.
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- Spectrophotometric Studies of Electron-Donor-Acceptor Equilibria: The Presence of Bi- and Ter-Molecular Complexes
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The donor-acceptor equilibria involving 2,3-dichloro-5-nitro-1,4-naphthoquinone (DClNNQ) and several substituted aromatic amines have been investigated spectrophotometrically in dichloromethane solution.Experimental evidence shows that they do not give 1 : 1 complexes alone.The results can be explained on the basis of the formation of termolecular complexes, in addition to 1 : 1 complexes.The formation constants for both 1 : 1 and 1 : 2 (A : D) complexes and their molar adsorptivities have been evaluated by using a multiparametric least squares computer program.
- Jayadevappa, E. S.,Budni, M. L.
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p. 145 - 153
(2007/10/02)
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- Topical Nonsteroidal Antipsoriatic Agents. 1. 1,2,3,4-Tetraoxygenated Naphthalene Derivatives
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On the basis of previous observations that both 2,3-dihydro-2,2,3,3-tetrahydroxy-1,4-naphthoquinone (oxoline, 1) and 6-chloroisonaphthazarin (2) had demonstrated antipsoriatic activity in vivo, a series of structural derivatives of 2 were prepared and examined in the Scholtz-Dumas topical psoriasis bioassay.Of these six (5, 6, 9a, 10, 11a, 11b), the most effective compound was found to be 6-chloro-1,4-diacetoxy-2,3-dimethoxynaphthalene (RS-43179,lonapalene, 11a).An extensive series of 1,2,3,4-tetraoxygenated naphthalenes (16-74) incorporating variations of the ester, eth er and aryl substituents were prepared as analogues of 11a to examine the structural requirements for activity and were screened in vivo as inhibitors of arachidonic acid induced mouse ear edema, a topical bioassay capable of detecting 5-lipoxygenase inhibitors.Net lipophilicity, hydrolytic stability, and ring substitution play significant roles in determining the observed in vivo activity.Lonapalene (11a) is currently in clinical development as a topical applied nonsteroidal antipsoriatic agent.
- Jones, Gordon H.,Venuti, Michael C.,Young, John M.,Murthy, D.V. Krishna,Loe, Brad E.,et al.
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p. 1504 - 1511
(2007/10/02)
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