RESUMO
Non-adenosine triphosphate (ATP) competitive, allosteric inhibitors provide a promising avenue to develop highly selective small-molecule kinase inhibitors. Although this class of compounds is growing, detection of such inhibitors can be challenging as standard kinase activity assays preferentially detect compounds that bind to active kinases in an ATP competitive manner. We have previously described a time-resolved fluorescence resonance energy transfer (TR-FRET)-based kinase binding assay using the competitive displacement of ATP competitive active site fluorescent probes ("tracers"). Although this format has gained acceptance, published data with this and related formats are almost entirely without examples of non-ATP competitive compounds. Thus, this study addresses whether this format is useful for non-ATP competitive inhibitors. To this end, 15 commercially available non-ATP competitive inhibitors were tested for their ability to displace ATP competitive probes. Despite the diversity of both compound structures and their respective targets, 14 of the 15 compounds displaced the tracers with IC(50) values comparable to literature values. We conclude that such binding assays are well suited for the study of non-ATP competitive inhibitors. In addition, we demonstrate that allosteric inhibitors of BCR-Abl and MEK bind preferentially to the nonphosphorylated (i.e., inactive) form of the kinase, indicating that binding assays may be a preferred format in some cases.
Assuntos
Avaliação Pré-Clínica de Medicamentos/métodos , Inibidores de Proteínas Quinases/farmacologia , Trifosfato de Adenosina/metabolismo , Regulação Alostérica/efeitos dos fármacos , Ligação Competitiva , Domínio Catalítico/efeitos dos fármacos , Transferência Ressonante de Energia de Fluorescência , Proteínas de Fusão bcr-abl/antagonistas & inibidores , Proteínas de Fusão bcr-abl/metabolismo , Humanos , Concentração Inibidora 50 , MAP Quinase Quinase 1/antagonistas & inibidores , MAP Quinase Quinase 1/metabolismo , Ligação Proteica , Inibidores de Proteínas Quinases/química , Proteínas Tirosina Quinases/antagonistas & inibidores , Proteínas Tirosina Quinases/metabolismoAssuntos
Proteínas de Arabidopsis/química , Arabidopsis/enzimologia , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/química , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Cristalografia por Raios X , Isoenzimas/química , Isoenzimas/genética , Isoenzimas/metabolismo , Modelos Moleculares , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/genética , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/metabolismo , Estrutura Terciária de Proteína , Especificidade por SubstratoRESUMO
The Center for Eukaryotic Structural Genomics (CESG) has established procedures for the purification of Arabidopsis proteins in a high-throughput mode. Recombinant proteins were fused with (His)(6)-MBP tags at their N-terminus and expressed in Escherichia coli. Using an automated AKTApurifier system, fusion proteins were initially purified by immobilized metal affinity chromatography (IMAC). After cleavage of (His)(6)-MBP tags by TEV protease, (His)(6)-MBP tags were separated from target proteins by a subtractive 2nd IMAC. As a part of quality assurance, all purified proteins were subjected to MALDI-TOF and ESI mass spectrometry to confirm target identity and integrity, and determine incorporation of seleno-methionine (SeMet) and (15)N and (13)C isotopes. The protocols have been used successfully to provide high quality proteins that are suitable for structural studies by X-ray crystallography and NMR.