SDS-induced Peptide Conformational Changes: From Triglycyl-glycine to Amyloid-β Oligomers Associated with Alzheimer’s Disease

  • Laura Ion
  • Catalina Ionica Ciobanu
  • Manuela Murariu
  • Vasile-Robert Gradinaru
  • Gabi Drochioiu


Sodium dodecyl sulfate (SDS) was introduced in polyacrylamide gel electrophoresis (PAGE) due to its capacity of helping proteins to become fully denatured and dissociated from each other. Numerous studies which have been undertaken, using electrospray ionization mass spectrometry (ESI–MS), reported on the process of peptide oligomerization. Many of these investigations have included tetraglycine (H2N–Gly–Gly–Gly–Gly–COOH; G4) as model peptide. The aim of this research is to investigate the effect of SDS on G4 oligomerization, and, especially, to emphasize the dismantling of oligomers under micellar conditions. In water, G4 peptide develops dimers and oligomers, which can also be evidenced in high proportion by MS in the gas phase. Although our results show that SDS is able to reduce the proportion of G4 oligomers, the aqueous G4-SDS system may contain G4 dimers, G4-SDS adducts alongside with the expected monomers and some alkaline metal adducts. The mechanism by which SDS disassembled G4 dimers, which includes sodium ion affinity toward negatively charged carboxyl and sulfonyl groups, was also discussed. Amyloid-β peptide1–40 conformation changed considerably and, especially, the proportion of α-helical populations increased upon SDS binding in a concentration-dependent manner. Molecular dynamics studies confirmed the tendency of Aβ molecules to form α-helical conformers, as the CD and FTIR studies showed.


Aβ peptide Tetraglycine ESI–MS CD FT-IR Sodium dodecyl sulfate Oligomerization 



This work was supported by Romanian Government (UEFISCDI Contract IDEI 313/2011). PhD student Laura Ion gratefully acknowledges the strategic grant POSDRU/159/1.5/S/137750 from EU.

Compliance with Ethical Standards

Conflict of interest

Laura Ion, Catalina Ionica Ciobanu, Manuela Murariu, Vasile-Robert Gradinaru, and Gabi Drochioiu declare that they have no conflict of interest.

Human and Animal Rights and Informed Consent

This article does not contain any studies with human or animal subjects performed by any of the authors.


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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • Laura Ion
    • 1
  • Catalina Ionica Ciobanu
    • 2
  • Manuela Murariu
    • 3
  • Vasile-Robert Gradinaru
    • 1
  • Gabi Drochioiu
    • 1
    • 3
  1. 1.Faculty of ChemistryAl. I. Cuza University of IasiIasiRomania
  2. 2.Research Department, Faculty of ChemistryAl. I. Cuza University of IasiIasiRomania
  3. 3.Petru Poni Institute of Macromolecular ChemistryIasiRomania

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