RESUMO
A series of inhibitors of Pim-2 kinase identified by high-throughput screening is described. Details of the hit validation and lead generation process and structure-activity relationship (SAR) studies are presented. Disclosure of an unconventional binding mode for 1, as revealed by X-ray crystallography using the highly homologous Pim-1 protein, is also presented, and observed binding features are shown to correlate with the Pim-2 SAR. While highly selective within the kinase family, the series shows similar potency for both Pim-1 and Pim-2, which was expected on the basis of homology, but unusual in light of reports in the literature documenting a bias for Pim-1. A rationale for these observations based on Pim-1 and Pim-2 K(M(ATP)) values is suggested. Some interesting cross reactivity with casein kinase-2 was also identified, and structural features which may contribute to the association are discussed.
Assuntos
Azepinas/química , Modelos Moleculares , Fenilpropionatos/química , Proteínas Proto-Oncogênicas c-pim-1/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-pim-1/química , Azepinas/síntese química , Sítios de Ligação , Caseína Quinase II/antagonistas & inibidores , Caseína Quinase II/química , Cristalografia por Raios X , Fenilpropionatos/síntese química , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
Benzimidazole 1 was identified as a selective inhibitor of ITK by high throughput screening. Hit-to-lead studies defined the SAR at all three substituents. Reversing the amide linkage at C6 led to 16, with a fivefold improvement of potency. This enhancement is rationalized by the conformational preference of the substituent. A model for the binding of the benzimidazoles to the ATP-binding site of ITK is proposed.
Assuntos
Benzimidazóis/química , Química Farmacêutica/métodos , Inibidores de Proteínas Quinases/síntese química , Proteínas Tirosina Quinases/antagonistas & inibidores , Trifosfato de Adenosina/química , Benzimidazóis/síntese química , Sítios de Ligação , Avaliação Pré-Clínica de Medicamentos/métodos , Inibidores Enzimáticos/farmacologia , Humanos , Ligação de Hidrogênio , Concentração Inibidora 50 , Modelos Químicos , Ligação Proteica , Inibidores de Proteínas Quinases/química , Relação Estrutura-AtividadeRESUMO
The design and synthesis of dipeptidyl disulfides and dipeptidyl benzoylhydrazones as selective inhibitors of the cysteine protease Cathepsin S are described. These inhibitors were expected to form a slowly reversible covalent adduct of the active site cysteine of Cathepsin S. Formation of the initial adduct was confirmed by mass spectral analysis. The nature and mechanism of these adducts was explored. Kinetic analysis of the benzoyl hydrazones indicate that these inhibitors are acting as irreversible inhibitors of Cathepsin S. Additionally, the benzoylhydrazones were shown to be potent inhibitors of Cathepsin S processing of Class II associated invariant peptide both in vitro and in vivo.
Assuntos
Catepsinas/antagonistas & inibidores , Inibidores de Cisteína Proteinase/síntese química , Inibidores de Cisteína Proteinase/farmacologia , Dissulfetos/síntese química , Dissulfetos/farmacologia , Hidrazonas/síntese química , Hidrazonas/farmacologia , Animais , Catepsina B/antagonistas & inibidores , Linhagem Celular , Desenho de Fármacos , Humanos , Cinética , Espectroscopia de Ressonância Magnética , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Elastase Pancreática/antagonistas & inibidores , Testes de Precipitina , Proteínas Recombinantes/antagonistas & inibidoresRESUMO
The specificity of the immune response relies on processing of foreign proteins and presentation of antigenic peptides at the cell surface. Inhibition of antigen presentation, and the subsequent activation of T-cells, should, in theory, modulate the immune response. The cysteine protease Cathepsin S performs a fundamental step in antigen presentation and therefore represents an attractive target for inhibition. Herein, we report a series of potent and reversible Cathepsin S inhibitors based on dipeptide nitriles. These inhibitors show nanomolar inhibition of the target enzyme as well as cellular potency in a human B cell line. The first X-ray crystal structure of a reversible inhibitor cocrystallized with Cathepsin S is also reported.