Re: [AMBER] chirality restraints for non-standard residue

From: Jio M <jiomm.yahoo.com>
Date: Fri, 16 Apr 2010 12:18:42 -0700 (PDT)

One more thing I forgot to mention. I want to do annealing at higher
temperature 1500K. can this prevent((r1=150., r2=170., r3=190.,
r4=210., rk2 =
50., rk3=50)) inversion at chiral center or other internal constraints
should be applied..



Dear Dr. Jason,





Thanks for reply






>This is a flat-well potential described in the manual


Sorry this was new to me thats why I asked in hurried manner





two more querries please,,





1) I used makeCHIR_RST for two, three different pdb files and got this
result only r1=150., r2=170., r3=190., r4=210., rk2 = 50.,
rk3=50.,  &end only. Is this same for all proteins and it was
written once at top of rst file like this (does that mean all peptide
bonds will use these values)





#  trans-omega constraint for residue 2


 &rst iat=23,22,3,2,


   r1=150., r2=170., r3=190., r4=210., rk2 = 50., rk3=50.,  &end


#  trans-omega constraint for residue 3


 &rst iat=35,34,24,23, &end


#  trans-omega constraint for residue 4


 &rst iat=51,50,36,35, &end





2) Can I use these values ((r1=150., r2=170., r3=190., r4=210., rk2 =
50., rk3=50)) for my nonstandard residue joined by peptide bond.. by
defining atoms








On Fri, Apr 16, 2010 at 7:15 AM, Jio M <jiomm.yahoo.com> wrote:


> Dear users,


>


>


>


> I have joined    chiral residue with a peptide bond to


> another residue. As I did annealing the configuration changed at the


> chiral center as expected. So I want to apply chiral restraints to the


> chiral center and want peptide bond to be trans


>


> I have seen by command make_CHIRAL_RST for normal protein pdb.


>


> &rst iat=23,22,3,2,


>


>


>    r1=150., r2=170., r3=190., r4=210., rk2 = 50., rk3=50.,  &end


>





This is a flat-well potential described in the manual.  Values between


r1 and r2 have a harmonic restraint with force constant equal to rk2.


Values between r2 and r3 have no restraint. Between r3 and r4 have a


harmonic restraint with force constant rk3.  The restraints before r1


and after r4 are linear and adjusted so that the total restraint


potential is continuous (for both the original function and 1st


derivative if I'm not mistaken).





>


>


> I am not able to get meaning of r1 r2 etc. If I am not wrong iat


> represents atom number and also they represent CA-N(of first amino


> acid)-C-CA (of second amino acid) that is CA-N--C-CA the peptide bond.


> Can I similarly do for my residues. What about r1, r2 r3 here???





You can put any atoms you want here.  Again, this section (NMR


restraints) is gone over in quite a bit of detail in the amber manual.





Good luck!


Jason


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Received on Fri Apr 16 2010 - 12:30:04 PDT
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