Hi
I looked at Daggett's paper and I understand what they did, I think.
There are no such tools in amber per se, but it should be rather trivial
for you use what we already have to get the needed data. Basically, they
compute average structures every 5 ps (cpptraj can do this, maybe with
an external loop driver), and then you compute the RMSD of a structure
at time t with the structure at t-DeltaT (5 ps in the example above).
Those rmsd should be 'small' while you are in one cluster, and jump up
when you change clusters. It is clear that the plot in Valerie's paper
is made up, they day as much. It is a graphical representation with no
real data.
Associated with this, you might want to use the clustering method in
cpptraj as:
1. cluster form frames 1 to N
2. cluster from frames 1 to N+1
if the +1 frame is in a different (new) cluster, then somewhere between
N and N+1 there was a transition state. That is effectively what
Daggett is doing.
Adrian
On 12/13/13 12:28 PM, Sangeetha B wrote:
> Dear Dan,
>
> Thanks for your reply.
>
> I have extracted a 2D RMSD matrix but it is not helpful to understand the
> conformational clustering.
>
> The method described by Levitt, M in 1983 (J. Mol. Biol. 168, 621-657)
> explains a method of RMSD analysis where after projection into 2D space,
> the distances between a set of points in two-dimensional plane explains the
> RMS deviations between a set of protein structures. This method can easily
> identify a transition state which is generally the first structure exiting
> the first cluster.
>
>
> I would like to generate a plot of this nature so that a transition state
> can be easily identified.
>
>
> Thanks in advance.
>
>
> On Fri, Dec 13, 2013 at 10:11 PM, Daniel Roe <daniel.r.roe.gmail.com> wrote:
>
>> Hi,
>>
>> I believe the analysis you are referring to is the construction of a graph
>> where the vertices represent structures and the edges represent the RMSD
>> between the structures. To my knowledge there you can't do this exactly in
>> Amber, but you can calculate a 2D RMSD matrix with cpptraj or ptraj. For
>> example, to look at the 2D RMSD between C-alpha atoms (cpptraj):
>>
>> 2drms .CA out ca2drms.gnu
>>
>> The ".gnu" extension tells cpptraj to write the file in gnuplot-readable
>> format.
>>
>> Hope this helps,
>>
>> -Dan
>>
>>
>>
>> On Fri, Dec 13, 2013 at 7:11 AM, Sangeetha B <sangeetha.bicpu.edu.in>
>> wrote:
>>
>>> Dear Amber users,
>>>
>>> I am working on protein folding/unfolding problem and I came across an
>>> article
>> http://www.sciencedirect.com/science/article/pii/S0022283696901722
>>> .
>>>
>>> I am aware of the problem in identifying a transition state in protein
>>> unfolding trajectory and this article (and few other related publications
>>> by Valerie Daggett) identify the transition state by *Ca RMSD based
>>> conformational clustering and its projection onto 3D space. *
>>>
>>> An analysis tool to obtain such a projection is available in CHARMM
>>> (RMSDyn).
>>>
>>> Is it possible to perform a similar analysis using AMBER.
>>>
>>> Any help in this regard would be grateful.
>>>
>>>
>>>
>>> --
>>> Thank you,
>>>
>>> With regards,
>>> B. Sangeetha
>>> _______________________________________________
>>> AMBER mailing list
>>> AMBER.ambermd.org
>>> http://lists.ambermd.org/mailman/listinfo/amber
>>>
>>
>>
>> --
>> -------------------------
>> Daniel R. Roe, PhD
>> Department of Medicinal Chemistry
>> University of Utah
>> 30 South 2000 East, Room 201
>> Salt Lake City, UT 84112-5820
>> http://home.chpc.utah.edu/~cheatham/
>> (801) 587-9652
>> (801) 585-6208 (Fax)
>> _______________________________________________
>> AMBER mailing list
>> AMBER.ambermd.org
>> http://lists.ambermd.org/mailman/listinfo/amber
>>
>
>
--
Dr. Adrian E. Roitberg
Colonel Allan R. and Margaret G. Crow Term Professor.
Quantum Theory Project, Department of Chemistry
University of Florida
roitberg.ufl.edu
352-392-6972
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Received on Fri Dec 13 2013 - 10:00:03 PST
