THE INFLUENCE OF DIPOLE MODIFIERS ON THE CHANNEL-FORMING ACTIVITY
OF AMYLOID AND AMYLOID-LIKE PEPTIDES IN LIPID BILAYERS
S.S. Efimova,1,* V.V. Zakharov,2,3 O.S. Ostroumova 1
1 Institute of Cytology RAS, St. Petersburg, 2 National Research Centre NRC «Kurchatov Institute», Gatchina,
and 3 St. Petersburg State Polytechnical University;
* e-mail: ssefimova@mail.ru
We have studied the steady-state transmembrane current induced by amyloid and amyloid-like peptides in
lipid bilayers in the presence of dipole modifiers. It has been shown that the addition of dipole modifier, phloretin,
to the membrane bathing solutions leads to an increase in the multichannel activity of amyloid β-peptide
fragment 25—35, [Gly35]-amyloid β-peptide fragment 25—35, prion protein fragment 106—126 and amyloid-
like peptides myr-BASP1 (1—13), myr-BASP1(1—19) and GAP-43(1—40). We have found that the effect
of phloretin is not the result of dipole potential changes due to adsorption of this modifier on the membrane.
Using the various fragments of amyloid â-peptide, presenilin, prion protein and neuronal proteins BASP1 and
GAP-43 allowes to conclude that the steady-state peptide-induced transmembrane current in the case of addition
of phloretin is due to the electrostatic interaction between the positively charged channel-forming agents and
negatively charged dipole modifier. The results obtained by electron microscopy have demonstrated that this
interaction increases degree of peptide oligomerization.
Key words:
bilayer lipid membranes, amyloidogenic peptides, dipole modifiers, membrane dipole potential
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