Hi,
I have tried it with GaussView. First, I have created a valacy in the zinc
ion and then replaced it with a water molecule. After That, I have saved
the coordinates into a PDB file and followed subsequent steps as specified
in MCPB.py tutorial. After optimization and frequency calculation, I also
have a look into the fchk file to check whether there are any
discrepancies. But nothing suspicious is there. So I proceed further by
generating prmtop and inpcrd file for my MD run. I have minimized my system
with SHAKE by putting a weak restraint of 2.0. After minimization, I got
stuck into the heating process after step 37 with the error message:
vlimit exceeded for step 37; vmax = 76.6693
Coordinate resetting (SHAKE) cannot be accomplished,
deviation is too large
NITER, NIT, LL, I and J are : 0 3 4651 9219 9221
Note: This is usually a symptom of some deeper
problem with the energetics of the system.
nmropt was on during my heating process. I have checked the mdcrd file by
saving each step for nstlim=1000. Going with the atom ids, I found out that
something is going on between the O and a H atom of our newly created water
molecule. I don't know how to proceed further as I have tested and tried
almost every suggestion that was given in the amber archive. Is there
anything I have done wrong?
I will definitely try to build the system with VMD again as per your
suggestion. Let's see what happens.
Thanks,
Satyajit Khatua
---------- Forwarded message ---------
Message: 13
Date: Fri, 20 Nov 2020 10:42:47 -0500
From: Pengfei Li <ambermailpengfei.gmail.com>
Subject: Re: [AMBER] Tri-coordination environment in zinc
To: AMBER Mailing List <amber.ambermd.org>
Message-ID: <E475C039-5450-4525-85C7-A3BED9A61E79.gmail.com>
Content-Type: text/plain; charset=us-ascii
Hi Satyajit,
Do you have graphic program like GaussView? GaussView can do such a job. I
guess VMD could also do that by using a plugin like Molefacture:
https://www.ks.uiuc.edu/Research/vmd/plugins/molefacture/ <
https://www.ks.uiuc.edu/Research/vmd/plugins/molefacture/>.
After you adding the coordinated water molecules and save the coordinates
into a PDB file, you can just copy the coordinates of the added water
molecules into your original PDB file with renaming that water residue
(renaming both residue name and atom names inside) consistent with the
AMBER naming scheme (residue name: HOH or WAT, and atom names are O, H1,
and H2), and resequencing the PDB file using pdb4amber.
Hope it helps,
Pengfei
> On Nov 3, 2020, at 12:06 AM, SATYAJIT KHATUA <satyajitkhatua09.gmail.com>
wrote:
>
> Hi,
>
> Can you suggest to me any other tool to do so?
>
> with regards,
> Satyajit Khatua
>
>
> ---------- Forwarded message ---------
> Message: 6
> Date: Sun, 1 Nov 2020 10:35:31 -0800
> From: Bill Ross <ross.cgl.ucsf.edu>
> Subject: Re: [AMBER] Tri-coordination environment in zinc
> To: amber.ambermd.org
> Message-ID: <eec483ff-eba4-ed99-e6d4-0dc151e5a5e3.cgl.ucsf.edu>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> Yes. It's harder to do with xleap than other graphic editors, but still
> might only take a few minutes.
>
> Bill
>
> On 11/1/20 9:38 AM, SATYAJIT KHATUA wrote:
>> Hi,
>>
>> Thanks for replying. Here, I am talking about one water intending to
>> satisfy the metal site coordination. Can I place the water by hand using
>> the leap editor?
>>
>> with regards,
>> Satyajit Khatua
>>
>>
>> ---------- Forwarded message ---------
>> Message: 7
>> Date: Thu, 29 Oct 2020 23:59:57 -0700
>> From: Bill Ross <ross.cgl.ucsf.edu>
>> Subject: Re: [AMBER] Tri-coordination environment in zinc
>> To: amber.ambermd.org
>> Message-ID: <9c0e181c-eae2-73db-90f6-a9f4970b1131.cgl.ucsf.edu>
>> Content-Type: text/plain; charset=utf-8; format=flowed
>>
>> If we're just talking about a few waters, why not just place them by
hand?
>>
>> Bill
>>
>>
>> On 10/29/20 10:39 PM, SATYAJIT KHATUA wrote:
>>> Hi,
>>>
>>> Sorry for replying this late. I thought that maybe using MCPB.py is a
>>> viable solution in this case and stopped following further updates
posted
>>> in the archive. Now, I understand the problems that I am going to face
if
>> I
>>> don't take care of this problem that you have mentioned. Previously, I
>> have
>>> also tried the modeling by striping the crystal waters of the PDB and
> then
>>> adding the suitable water box to see if any water molecule falls within
>> the
>>> coordination distance of zinc ion but none to avail. Can you please help
>> me
>>> with the ways about how to saturate the metal site with the water
>> molecule?
>>> That will be helpful.
>>>
>>> with regards,
>>> Satyajit Khatua
>>>
>>>
>>> ---------- Forwarded message ---------
>>> Message: 7
>>> Date: Thu, 22 Oct 2020 17:22:53 -0400
>>> From: Pengfei Li <ambermailpengfei.gmail.com>
>>> Subject: Re: [AMBER] Tri-coordination environment in zinc
>>> To: AMBER Mailing List <amber.ambermd.org>
>>> Message-ID: <2D91EE0A-7C34-4DFF-BA87-7654944421CE.gmail.com>
>>> Content-Type: text/plain; charset=us-ascii
>>>
>>> Hi Satyajit,
>>>
>>> For this case maybe it is better for you to saturate the metal site
first
>>> with an additional water before the MCPB.py modeling. If the metal site
> is
>>> not saturated, it could be challenging to get meaningful results for the
>>> quantum calculations.
>>>
>>> Pengfei
>>>
>>>> On Sep 19, 2020, at 12:36 AM, SATYAJIT KHATUA <
> satyajitkhatua09.gmail.com
>>> wrote:
>>>> Dear Users,
>>>>
>>>> Anyone here have worked with tri-coordination environment on zinc in
>>> protein?? Recently, I am working on a superantigen protein that contains
> a
>>> tri-coordinated environment (two bound His- and one Asp-) on zinc.
> Usually
>>> zinc possess a tetra-coordination. In crystallography paper, they told
>> that
>>> possibly there is a water molecule on fourth position although they
didnt
>>> find any signature on electron density map. So can someone give some
>> inputs
>>> about the parameterization of this zinc coordination through amber force
>>> fields?? Any suggestions about some tutorials or papers in this regard
>> will
>>> also be appreciated.
>>>> Thanks in advance,
>>>> Satyajit Khatua
>>>> _______________________________________________
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>>>> http://lists.ambermd.org/mailman/listinfo/amber
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Received on Sat Nov 21 2020 - 02:30:03 PST
