AMBER Archive (2005)

Subject: Re: AMBER: DNA strands separate

From: Angelo Pugliese (angelo_at_holmes.cancres.nottingham.ac.uk)
Date: Wed Jul 06 2005 - 09:04:36 CDT

Hi Ivan,

I mean may be the changed parameters could affect the stability of the helix. Of
course I mean the parameters before the tragic event.

Sorry maybe i did not explain my thoughts very clearly.

Angelo

ivan_at_mmb.pcb.ub.es wrote:

> Dear Angelo,
>
> Sorry, I don't exactly see what you mean
>
> In my perturbation the DNA double helix is completely destroyed and
> therefore I can't measure any parameter with Curves. My two modifications
> surely will change these parameters but the DNA double helix should keep
> its normal appeareance.
>
> Did I understand your suggestion properly?
>
> thanks a lot,
>
> Ivan
>
> On Wed, 6 Jul 2005, Angelo Pugliese wrote:
>
> > HI Ivan,
> >
> > Did u check if your two modifications changed the parameters of the double
> > helix.....i mean over all the lenght of the double helix? U can use a program
> > like CURVES to measure these parameters.
> >
> > Angelo
> >
> >
> > ivan_at_mmb.pcb.ub.es wrote:
> >
> > > Dear amber users,
> > >
> > > I am doing a perturbation (MD/TI) with sander (amber8) and I mutate two
> > > hidrogen- bonded base pairs at the same time in a DNA double helix (dickerson
> > > dodecamer).
> > >
> > > My mutation consists in Ade --> Gua, and Cyto1 --> Cyto2 ( where cytoX
> > > are two tautomers of cytosine)
> > >
> > > I made a prior equilibration of the system and nothing anomalous happens,
> > > but when I turn to the perturbation I found that the DNA strands separate
> > > along the perturbation i.e. firstly, some hidrogen bonds increase their
> > > distance and finally the whole helix is completely open.
> > >
> > > I would think that this could be because of two appearing/disappearing
> > > groups that leads to an instability but this would also mean that the
> > > DNA separation would begin in the base pairs that I am mutating, and this
> > > is not my case.
> > >
> > > What reason can a DNA double helix have to get separated ? I guess that
> > > this can be due to some kind of erronous electrostatic interactions but I
> > > have carefully checked my charges ...
> > >
> > > Please, any comments are kindly acknowledged.
> > >
> > > thanks in advance
> > >
> > > --
> > > _______________________________________________
> > > / \
> > > / Ivan Marchan Carvajal \
> > > | (PhD Student) |
> > > | |
> > > | Institut de Recerca Biomedica de Barcelona |
> > > | Parc Cientific de Barcelona |
> > > | Molecular Modelling & Bionformatics Group |
> > > | http://mmb.pcb.ub.es |
> > > | |
> > > | C/ Josep Samitier 1-5 08028 Barcelona |
> > > | Tel: +34.93.403.71.55 Fax: +34.93.403.71.57 |
> > > | |
> > > | E-mail: ivan_at_mmb.pcb.ub.es |
> > > | theochem_at_hotmail.com |
> > > | Website: http://mmb.pcb.ub.es/~ivan |
> > > \ /
> > > \_________________________________________________/
> > >
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