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

From: Kenno Vanommeslaeghe (
Date: Wed Jul 24 2013 - 11:07:42 CDT

This may be a bit beyond the scope of this mailinglist, but my opinion
would be that if you start from a premise so unphysical as a phospholipid
membrane without counterions, there's nothing that can make it "reliable
in biological terms". Like charges repel; in the long run, it will
probably fall apart whether you use constant area of not. If I were you, I
would look into a different way of attaining whatever your ultimate goal is.

On 07/24/2013 04:37 AM, Villalain Boullon, Jose wrote:
> Dear All,
> I have looked for similar questions in the mailing list but I have not
> found any response to my doubts.
> I am trying to set up a system containing a peptide (out of the
> membrane), a membrane containing negatively charged phospholipids and
> water. The system is either neutralized or not and I want to check the
> possibility of the peptide to insert in the membrane under those conditions.
> First question. The system, when composed of the membrane containing
> negatively charged phospholipids _without being neutralized_, expands in
> the xy direction. The same system but neutralized does not expand (using
> the same conf file). I suppose that it should be possible to set
> “useconstantarea” to “yes” to avoid the spreading, but I have a question:
> would it be such a system and condition reliable in biological terms?.
> Second one, following the first. If I set “useconstantarea” to “yes” I
> suppose that the peptide would never insert in the membrane, even if the
> peptide, because of its hydrophobicity, tends to insert into it. Is that
> supposition right?.
> Third, following the second. If I can not set “useconstantarea” to “yes”,
> which is the parameter I should use to maintain the membrane without
> spreading in the xy direction ?.
> Many thanks in advance,
> José.

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