On 29/02/2012 7:21 PM, aiswarya pawar wrote:
Mark,

i want to know which water atoms stay within a cut off to protein atom.

OK, but as you will read in g_mindist -h, it will count such atoms and not identify which they were...

ie i need the duration at which a water resides on the protein atoms.

... and identity of the atoms is needed for measuring duration of contact. g_dist does something like this, and reading g_mindist -h should have prompted you to find this out.

Otherwise, you will have to construct an index group for each water molecule, and script a loop to examine each water molecule separately using some tool that observes what you really want to measure.

so for that i need the whole 5ns frames because am looking for water molecules which reside more than 50% of time.

You also need to be clear about whether you care about continuous contact. Does a water molecule that oscillates at a distance around the cutoff reside about 50% of the time?

You still don't need high time resolution for testing whether this analysis might give you the information you want. The water molecules that are in contact for more than 50% of the time (continuous or not) will show up in 5 snapsnots spaced every nanosecond. 5000 snapshots every picosecond is better, but not if you can't afford to wait for it.

Mark


Thanks

On Wed, Feb 29, 2012 at 12:41 PM, Mark Abraham <mark.abra...@anu.edu.au <mailto:mark.abra...@anu.edu.au>> wrote:

    On 29/02/2012 6:01 PM, aiswarya pawar wrote:
    Mark,

    Right now am computing distance between each protein atom against
    all water atoms,

    That's expensive. mdrun goes to great lengths to speed up
    computing billions of distances.

    which is taking too long for 5ns run. i cant reduce the frames

    Yes you can. Even if you think you need data from every frame, you
    probably don't because they're correlated with each other, and at
    the very least you can do a pilot study on a frame every 100ps or
    every nanosecond before committing to one on all the frames.


    either the number of water atoms. So is there any alternate.


    You are not likely to get a better solution if you only describe
    your attempt, rather than describe the objective. Asking "how do I
    hammer harder?" if you're hammering a screw makes it impossible to
    get the correct solution "Use a screwdriver".

    Mark


    Thanks

    On Wed, Feb 29, 2012 at 12:27 PM, Mark Abraham
    <mark.abra...@anu.edu.au <mailto:mark.abra...@anu.edu.au>> wrote:

        On 29/02/2012 5:17 PM, aiswarya pawar wrote:
        Dear all,

        Am running g_mindist on large number of atoms, i would like
        to know whether i can run this on more than one processors
        say 8 processors to speed up the task?

        No. If it will take too long, you need to reduce your number
        of frames (trjconv), or the number of atoms (also trjconv),
        or some such.

        Mark


        and will this effect the output in anyways.

        Thanks,

-- Aiswarya B Pawar






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-- Aiswarya B Pawar

    Project Assistant,
    Bioinformatics Dept,
    Indian Institute of Science
    Bangalore






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--
Aiswarya  B Pawar

Project Assistant,
Bioinformatics Dept,
Indian Institute of Science
Bangalore





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