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

From: Aron Broom (
Date: Wed Jul 24 2013 - 12:03:47 CDT

Is there a particular reason you don't want to neutralize the system?

On Wed, Jul 24, 2013 at 12:07 PM, Kenno Vanommeslaeghe <> wrote:

> 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.

Aron Broom M.Sc
PhD Student
Department of Chemistry
University of Waterloo

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