Quantitative assessment of paraoxon adsorption to amphiphilic β-sheet peptides presenting the catalytic triad of esterases

Avigail Baruch Leshem, Sivan Isaacs, Sachin K. Srivastava, Ibrahim Abdulhalim, Ariel Kushmaro, Hanna Rapaport

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Organophosphate compounds that are used as pesticides affect the nervous system by binding irreversibly to the active site of the enzyme acetylcholine esterase (AChE) and disrupting neuro-signaling nerve cells. In this study we characterized adsorption of paraoxon to a set of designed peptides that present different arrangements of the three amino acids of the AChE catalytic site: histidine, glutamic-acid and serine. The peptides set included two β-strands with no net charge and three β-hairpins that differ in their net charge. Circular dichroism, Thioflavin T assays and TEM images provided only qualitative insights on paraoxon binding to the different peptides. Paraoxon binding to the different peptides was measured with dialysis membrane tubes filled with the peptide solutions and suspended in a reservoir of paraoxon solution. Among all the tested peptides, the single strand peptide, denoted ssESH exhibited at 100 μM in random conformation prefibrillar state, the maximum paraoxon adsorption, with a binding mol ratio of one paraoxon per two peptides and an estimated equilibrium binding constant 5 ∗ 104 M−1. The three β-hairpin peptides demonstrated that a net negative charge is unfavorable for paraoxon adsorption. Surface enhanced Raman spectroscopy measurements with ssESH enabled the detection of nanomolar adsorbed concentrations of paraoxon.

Original languageEnglish
Pages (from-to)328-337
Number of pages10
JournalJournal of Colloid and Interface Science
StatePublished - 15 Nov 2018


  • Catalytic triad
  • Circular dichroism
  • Organophosphates
  • Surface enhanced Raman spectroscopy
  • Thioflavin T
  • β-hairpin
  • β-sheet

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry


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