Re: [AMBER] Error in Minimization

From: Zhonghua Xia <zhonghua.xia.helmholtz-muenchen.de>
Date: Fri, 15 Mar 2019 16:37:48 +0100

Dear Bill and David,

I appreciate your kind help!

Actually I went back to see the mol2 file. Then I found that antechamber cannot identify aromatic bond. When I use antechamber to convert pdb to mol2 for the ligand, it just converts every connection to single bond.

Also, I found antechamber and tleap cannot identify chlorine atom. I tried to manually change notation of chlorine to CL, cl or Cl in the mol2 file and pdb file generated by pdb4amber. No matter which way I use, finally I can’t get the molecule correctly with chlorine atom as shown by MOE and pymol.

Could you give me any help on this?

Kind regards,
Zhonghua

> On Mar 8, 2019, at 3:13 PM, David A Case <david.case.rutgers.edu> wrote:
>
> On Fri, Mar 08, 2019, Zhonghua Xia wrote:
>
>> Initial minimisation with Cartesian restrains for the solvent (hold the protein and Cl-)
>> &cntrl
>> imin=1, maxcyc=3000,
>> ntr=1,
>> restraint_wt=100,
>> restraintmask=':1-90'
>> &end
>
> Set ntpr=1 to get more detailed output. Also, you can use the "check"
> command in cpptraj to analyze your system for bad contacts.
>
>>
>> NSTEP ENERGY RMS GMAX NAME NUMBER
>> 1 4.3472E+08 2.4011E+02 1.9793E+04 C 1441
>>
>> BOND = 9784.2491 ANGLE = 1786.4015 DIHED = 934.9579
>> VDWAALS = ************* EEL = -62579.0562 HBOND = 0.0000
>> 1-4 VDW = 1083.6816 1-4 EEL = 4202.4250 RESTRAINT = 0.0000
>
> Still, it's a bit unusual that an initial energy of "only" 4 x 10^8
> won't minimize away. Try reducing your restraint weight by at least a
> factor of 10. If the bad contact is in residues 1-90, then your
> powerful restraints are forcing those atoms to stay where they are.
> Hence you may have to two very strong and competing energy terms, one
> trying to relieve a bond contact and another trying to keep it in place.
>
> ...good luck...dac
>
>
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Received on Fri Mar 15 2019 - 09:00:03 PDT
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