RESUMO
The aqueous solution structure of protoxin II (ProTx II) indicated that the toxin comprises a well-defined inhibitor cystine knot (ICK) backbone region and a flexible C-terminal tail region, similar to previously described NaSpTx III tarantula toxins. In the present study we sought to explore the structure-activity relationship of the two regions of the ProTx II molecule. As a first step, chimeric toxins of ProTx II and PaTx I were synthesized and their biological activities on Nav1.7 and Nav1.2 channels were investigated. Other tail region modifications to this chimera explored the effects of tail length and tertiary structure on sodium channel activity. In addition, the activity of various C-terminal modifications of the native ProTx II was assayed and resulted in the identification of protoxin II-NHCH3, a molecule with greater potency against Nav1.7 channels (IC50=42 pM) than the original ProTx II.
Assuntos
Canal de Sódio Disparado por Voltagem NAV1.7/fisiologia , Peptídeos/química , Venenos de Aranha/química , Bloqueadores do Canal de Sódio Disparado por Voltagem/química , Animais , Células HEK293 , Humanos , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Peptídeos/síntese química , Peptídeos/farmacologia , Ratos , Venenos de Aranha/síntese química , Venenos de Aranha/farmacologia , Relação Estrutura-Atividade , Bloqueadores do Canal de Sódio Disparado por Voltagem/síntese química , Bloqueadores do Canal de Sódio Disparado por Voltagem/farmacologiaRESUMO
A pituitary adenylate cyclase-activating peptide (PACAP) analogue (HSDAVFTDNYTRLRKQVAAKKYLQSIKNKRY, P66) was formulated in several non-aqueous solvents in anticipation of improved shelf-life stability. However, the stability of this peptide in these solvents was found to be as poor as in an aqueous solution. The major degradation reaction in non-aqueous solvents was dimer formation. The proposed mechanism for dimerization was a nucleophilic attack of a basic amino acid on cyclic imide formed by dehydration or deamidation of Asp or Asn. Two approaches were found to be effective in stabilizing the peptide in non-aqueous solvents: (1) acidification of the peptide and (2) use of zinc chloride in the formulation. Stabilization could be attributed to reduction of the nucleophilicity of the reactive groups through protonation and metal-peptide interaction through chelation. The stabilization approaches are applicable only in a non-aqueous environment for this peptide, and possibly for other peptides with similar reactive moieties.
Assuntos
Polipeptídeo Hipofisário Ativador de Adenilato Ciclase/química , Solventes/química , Cloretos/química , Dimerização , Estabilidade de Medicamentos , Armazenamento de Medicamentos , Concentração de Íons de Hidrogênio , Compostos de Zinco/químicaAssuntos
Depsipeptídeos/química , Depsipeptídeos/síntese química , Células Cultivadas/efeitos dos fármacos , Ciclização , Depsipeptídeos/farmacologia , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/crescimento & desenvolvimento , Lactamas/química , Modelos Químicos , Peptídeos Cíclicos/química , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Streptococcus pneumoniae/efeitos dos fármacos , Streptococcus pneumoniae/crescimento & desenvolvimentoRESUMO
Three synthetic routes towards a novel estrogen receptor ligand template based on a rigid bicyclo-[3.3.1]-nonene core have been investigated. The prototype compound exhibits potent binding at the ERbeta receptor and promising estrogen receptor subtype selectivity.
