RESUMEN
Human ornithine aminotransferase (hOAT) is a pyridoxal 5'-phosphate (PLP)-dependent enzyme that was recently found to play an important role in the metabolic reprogramming of hepatocellular carcinoma (HCC) via the proline and glutamine metabolic pathways. The selective inhibition of hOAT by compound 10 exhibited potent in vivo antitumor activity. Inspired by the discovery of the aminotransferase inactivator (1S,3S)-3-amino-4-(difluoromethylene)cyclopentane-1-carboxylic acid (5), we rationally designed, synthesized, and evaluated a series of six-membered-ring analogs. Among them, 14 was identified as a new selective hOAT inactivator, which demonstrated a potency 22× greater than that of 10. Three different types of protein mass spectrometry approaches and two crystallographic approaches were employed to identify the structure of hOAT-14 and the formation of a remarkable final adduct (32') in the active site. These spectral studies reveal an enzyme complex heretofore not observed in a PLP-dependent enzyme, which has covalent bonds to two nearby residues. Crystal soaking experiments and molecular dynamics simulations were carried out to identify the structure of the active-site intermediate 27' and elucidate the order of the two covalent bonds that formed, leading to 32'. The initial covalent reaction of the activated warhead occurs with *Thr322 from the second subunit, followed by a subsequent nucleophilic attack by the catalytic residue Lys292. The turnover mechanism of 14 by hOAT was supported by a mass spectrometric analysis of metabolites and fluoride ion release experiments. This novel mechanism for hOAT with 14 will contribute to the further rational design of selective inactivators and an understanding of potential inactivation mechanisms by aminotransferases.
Asunto(s)
Inhibidores Enzimáticos/farmacología , Ornitina-Oxo-Ácido Transaminasa/antagonistas & inhibidores , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/química , Humanos , Cinética , Espectrometría de Masas , Modelos Moleculares , Estructura Molecular , Ornitina-Oxo-Ácido Transaminasa/metabolismoRESUMEN
Antisense oligonucleotides (ASOs) have the potential to discriminate between subtle RNA mismatches such as SNPs. Certain mismatches, however, allow ASOs to bind at physiological conditions and result in RNA cleavage mediated by RNase H. We showed that replacing DNA nucleotides in the gap region of an ASO with other chemical modification can improve allele selectivity. Herein, we systematically substitute every position in the gap region of an ASO targeting huntingtin gene (HTT) with fluorinated nucleotides. Potency is determined in cell culture against mutant HTT (mtHTT) and wild-type HTT (wtHTT) mRNA and RNase H cleavage intensities, and patterns are investigated. This study profiled five different fluorinated nucleotides and showed them to have predictable, site-specific effects on RNase H cleavage, and the cleavage patterns were rationalized from a published X-ray structure of human RNase H1. The results herein can be used as a guide for future projects where ASO discrimination of SNPs is important.
RESUMEN
The efficient synthesis of trans-2-ethenylcyclopropyl aryl ketones via an intramolecular SN2-like displacement of an allylic ester is reported. A novel 1,5-acyl shift process is also observed that contributes to the product mixture. Theoretical calculations provide a rationale for the observed product ratio.
RESUMEN
In the treatment of echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase positive (ALK+) non-small-cell lung cancer (NSCLC), secondary mutations within the ALK kinase domain have emerged as a major resistance mechanism to both first- and second-generation ALK inhibitors. This report describes the design and synthesis of a series of 2,4-diarylaminopyrimidine-based potent and selective ALK inhibitors culminating in identification of the investigational clinical candidate brigatinib. A unique structural feature of brigatinib is a phosphine oxide, an overlooked but novel hydrogen-bond acceptor that drives potency and selectivity in addition to favorable ADME properties. Brigatinib displayed low nanomolar IC50s against native ALK and all tested clinically relevant ALK mutants in both enzyme-based biochemical and cell-based viability assays and demonstrated efficacy in multiple ALK+ xenografts in mice, including Karpas-299 (anaplastic large-cell lymphomas [ALCL]) and H3122 (NSCLC). Brigatinib represents the most clinically advanced phosphine oxide-containing drug candidate to date and is currently being evaluated in a global phase 2 registration trial.
Asunto(s)
Antineoplásicos/farmacología , Descubrimiento de Drogas , Neoplasias Pulmonares/tratamiento farmacológico , Compuestos Organofosforados/farmacología , Fosfinas/química , Inhibidores de Proteínas Quinasas/farmacología , Pirimidinas/farmacología , Proteínas Tirosina Quinasas Receptoras/antagonistas & inhibidores , Administración Oral , Quinasa de Linfoma Anaplásico , Animales , Antineoplásicos/administración & dosificación , Antineoplásicos/química , Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Carcinoma de Pulmón de Células no Pequeñas/enzimología , Carcinoma de Pulmón de Células no Pequeñas/patología , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Femenino , Humanos , Neoplasias Pulmonares/enzimología , Neoplasias Pulmonares/patología , Ratones , Ratones SCID , Conformación Molecular , Neoplasias Experimentales/tratamiento farmacológico , Neoplasias Experimentales/patología , Compuestos Organofosforados/administración & dosificación , Compuestos Organofosforados/química , Fosfinas/farmacología , Inhibidores de Proteínas Quinasas/administración & dosificación , Inhibidores de Proteínas Quinasas/química , Pirimidinas/administración & dosificación , Pirimidinas/química , Ratas , Proteínas Tirosina Quinasas Receptoras/genética , Proteínas Tirosina Quinasas Receptoras/metabolismo , Relación Estructura-ActividadRESUMEN
The efficient synthesis, antiviral activity, and duplex-stabilizing properties of both isomers of the 2'-fluoro analogue of Northern methanocarbathymidine (N-MCT), 2 and 3, are reported. We show that 2'-F incorporation on the N-MCT scaffold has a strong stabilizing effect on duplex thermal stability.
Asunto(s)
Oligonucleótidos/química , Oligonucleótidos/síntesis química , Timidina/análogos & derivados , Modelos Moleculares , Conformación Molecular , Estructura Molecular , Conformación de Ácido Nucleico , Timidina/químicaRESUMEN
N-Acetylindoles can be oxidatively coupled with arenes such as benzene or pentafluorobenzene in dioxane. The use of Cu(OAc)(2) as the stoichiometric oxidant produces selective arylation at the 3-position of indole while AgOAc produces selective arylation at indole's 2-position.
RESUMEN
The aerobic oxidative coupling of arenes such as benzofuran and N-substituted indoles with benzene and derivatives thereof is described. The reaction is shown to take place in both inter- and intramolecular scenarios.