Re: Re: Using negatively charged phospholipids and no neutralization, membrane expands in the xy direction .......

From: Kenno Vanommeslaeghe (
Date: Thu Jul 25 2013 - 11:12:23 CDT

Nature has a strong electroneutrality requirement. You can stick your
membrane on top of a Van de Graaff generator and still have only a tiny
fraction of a percent net ionization. I don't think there are experimental
conditions in which one can maintain a significantly negatively charged
membrane without counterions. You can wash all you want, but there will
always be a more or less fixed number of sodiums, potassiums, calciums or
hydroniums hanging around within a few nm of the membrane, even if the
bulk solution is devoid of them. Unless you neutralize the ionizable
groups with acid, of course.

On 07/25/2013 06:52 AM, Villalain Boullon, Jose wrote:
> Dear All,
> Thank you very much for your responses.
> The reason I want to test the neutralized and non-neutralized systems is
> that we are working with a peptide which interacts with negatively charged
> phospholipids BUT IN THE ABSENCE of positive ions (sodium, calcium);
> i.e., the lower the ionic strength, the higher the interaction is. Under
> these conditions it seems also that the peptide, apart from interacting
> with the phospholipids, changes its conformation.
> My best regards,
> Josť.

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