AMBER Archive (2008)

Subject: Re: AMBER: [amber/glycam] dealing with fucose...

From: Waqas Nasir (nasirwaqas1983_at_yahoo.com)
Date: Sat Jul 12 2008 - 14:44:13 CDT


Hi,

Thanks for the reply, and sorry for bothering you. The thing is that I
just want to load the fucose and galactose residues in Xleap to get started. I am
attaching a sample pdb file taken from 2vng.pdb which contains only
carbohydrate residues FUC and GAL. If you could just load this into the
xleap and tell me what steps have you taken to do so, it will be a
great help. Please note that this pdb file also contains that O1
(oxygen at position 1) in GAL residue that means that you will have to
manage it through ROH. One more thing that I want to tell you is that
the case which I am dealing with is one of non bonded interaction of
carbohydrate with protein making a complex.

I thank you once again for your help. I feel that I am very close and hopefully it will be over in a couple of days.

Awaiting your response,
Kind regards,
Waqas.

----- Original Message ----
From: Lachele Foley (Lists) <lf.list_at_gmail.com>
To: amber_at_scripps.edu
Sent: Friday, July 11, 2008 5:19:17 PM
Subject: Re: AMBER: [amber/glycam] dealing with fucose...

What are you trying to build? Or, more specifically, what is it that
your pdb file should represent?

If your 0LB residue is connected to another glycan or to a protein,
then you don't want an ROH in the file in a position associated with
the 0LB. That will only confuse things. The same goes for your ZLB.
If this is the case, you're going to put the other glycan (or protein)
where the ROH would have gone.

You only want an ROH if you have a lone oligosaccharide (or
monosaccharide, etc.) that is not attached to a protein, etc.
Otherwise, leap will get confused because there are too many atoms in
the wrong places.

The complaint about the HO1 indicates to me that leap doesn't know
what to do with that atom (or, rather, the fact that it seems to be
missing).

If this doesn't help, and if you want to, send me your pdb and leap
input files. If you want privacy, send them to me off-list. I'll see
what I can do.

:-) Lachele

On 7/11/08, Waqas Nasir <nasirwaqas1983_at_yahoo.com> wrote:
>
> Hi Lachele,
>
> Hope you are fine. Thanks again for the help that you have provided me with. It has really proved to be substantial.
>
> Well, again as you mentioned I had a brief look at the tools manual and now I think I do understand your point quite clearly. What I have done now is that I have renamed 1fA to 0FA, 1LB to oLB (where oLB = sequence { ROH 0LB }) and ZLB to zLB (where zLB = sequence { ROH ZLB }) in the pdb file.
>
> The oxygens are at the position where they are supposed to be. Every thing looks perfectly alright until I run the loadpdb command which results in the following error;
> -----------------------------------------------------------------------------------------------------------
> !FATAL ERROR----------------------------------------
> !FATAL: In file [chirality.c], line 121
> !FATAL: Message: Atom HO1 is not in the first list
> !
> !ABORTING.
> -----------------------------------------------------------------------------------------------------------
>
> I am extremely sorry for the trouble that I am causing you, but it seems every time there is something silly going on with me. Anyways, I will be very grateful to you if you could help me out this time as well.
>
> Thanks alot for the assistance... it was all worthed.
> Thanks again,
> Stay blessed!
>
> Kind Regards,
> Waqas.
>
>
> --- On Thu, 7/10/08, Lachele Foley (Lists) <lf.list_at_gmail.com> wrote:
>
> From: Lachele Foley (Lists) <lf.list_at_gmail.com>
> Subject: Re: AMBER: [amber/glycam] dealing with fucose...
> To: amber_at_scripps.edu
> Date: Thursday, July 10, 2008, 10:24 AM
>
>
> Waqas,
>
> Glad to be of help.
>
> The first
> thing I see is that the residue ZLB should not contain an O1
> atom at all, but it appears that it does. Perhaps the pdb file has an
> O1 in its ZLB residue. It might be sufficient, for this problem, to
> delete that atom from the file. It also appears that your ZLB does
> not have an O2 atom because leap is trying to add one. It is probably
> ok to let leap add that atom. I also suspect that your 1LB residues
> should actually be named 0LB (this might also be the case for your
> fucose residue). See the next paragraph, and then you can decide.
>
> Here's a little more about our naming convention: As you know, when
> the glycans link together, they lose an "HOH". Our residues are set
> up so that the anomeric position loses the OH (except when anomeric
> links to anomeric), and the non-anomeric position loses the H. All
> residues (with a special exception, below) should be missing an oxygen
> at their anomeric carbon. So, to
> get, for example, a complete,
> normal, a-D-Glcp, you have to add an ROH (-OH residue, named ROH to
> avoid confusion) to complete the molecule at the anomeric position.
> The AmberTools manual has much more to say about this, and you might
> find the information there helpful. The initial residue numbers tell
> use where there are attachments in addition to the anomeric position.
> So, for example, 3GB tells us that the b-D-Glcp has attachments at its
> O3 as well as at the anomeric position. A residue that attaches only
> at the anomeric position is numbered zero, e.g., 0GB. A plain
> a-D-Galp molecule, therefore, in our naming convention, is ROH-0LA.
> The special residue 1GB is used only when two anomeric posititions
> attach to each other, e.g. 1GB-0GB, which is b-D-Glcp-1-1-b-D-Glcp
> (1GB exists because one of them has to have an oxygen). Of course,
> for some sugars, the anomeric carbon is not C1, and the names
> behave
> accordingly. Note, in light of this, that your glycine must contain
> the oxygen that forms the link between the protein and the glycan
> (unless it doesn't link at the anomeric position). Leap appears to be
> adding a linkage oxygen to the glycine. If you are attaching the ZLB
> to the glycine at the ZLB's C1, deleting the O1 from the ZLB should
> make things better.
>
> Please see the AmberTools manual, section 3.5, for a much more
> detailed discussion of this. I think it will answer many of your
> questions -- and might clarify any confusion I caused in the last
> paragraph. You will also find examples of leap input commands.
>
> Let me know how it goes.
>
> :-) Lachele
>
>
>
> On 7/10/08, Waqas Nasir <nasirwaqas1983_at_yahoo.com> wrote:
> >
> >
> >
> >
> >
> > Hi Lachele,
> >
> > First of all thanks a lot for a quick reply. I really do appreciate that.
> It was terribly
> needed and useful. Thanks once again. The post was really very
> helpful.
> >
> > What I have done now is that I have downloaded the glycam06 parameter and
> prep files from http://www.glycam.com/gl_params.html as you mentioned. After
> that I have renamed fucose to 1fA, and galactoses to 1LB and ZLB respectively
> in the pdb file, according to the naming convention on the website.
> (http://www.glycam.com/CCRC/biombuilder/biomb_index.jsp)
> >
> > Right now, the problem that I have is that the residue ZLB (2,3 Beta D
> Galactose) has the hydrogen atom at position 1, where I have the oxygen in the
> pdb file. This causes xleap to flag a couple of errors when I try to save the
> top and crd files. Xleap adds the missing oxygens when I load the pdb file.
> >
> > Here is the output from xleap on loading pdb
> file:
> >
> ------------------------------------------------------------------------------------------------------------------
> > Added missing heavy atom: .R<CGLY 530>.A<OXT 8>
> > Created a new atom named: O1 within residue: .R<ZLB 532>
> > Added missing heavy atom: .R<ZLB 532>.A<O2 19>
> > Added missing heavy atom: .R<1LB 533>.A<O1 1>
> > Added missing heavy atom: .R<CGLY 1076>.A<OXT 8>
> > Created a new atom named: O1 within residue: .R<ZLB 1078>
> > Added missing heavy atom: .R<ZLB 1078>.A<O2 19>
> > Added missing heavy atom: .R<1LB 1079>.A<O1 1>
> > total atoms in file: 5306
> > Leap added 5582 missing atoms according to residue templates:
> > 6 Heavy
> > 5576 H / lone pairs
> > The file contained 2 atoms not in residue
> templates
> >
> >
> ----------------------------------------------------------------------------------------------------------------
> >
> > And, here is the output from xleap when I try to save the top and crd
> files:
> >
> >
> ----------------------------------------------------------------------------------------------------------------
> > Checking Unit.
> > ERROR: The unperturbed charge of the unit: -15.164000 is not integral.
> > WARNING: The unperturbed charge of the unit: -15.164000 is not zero.
> > FATAL: Atom .R<ZLB 532>.A<O1 21> does not have a type.
> > FATAL: Atom .R<ZLB 1078>.A<O1 21> does not have a type.
> > Failed to generate parameters
> > Parameter file was not saved.
> >
> ----------------------------------------------------------------------------------------------------------------
> >
> >
> > I would be very thanful to you if you
> could respond to this and help me
> out.
> > Waiting for you response,
> > Thanks,
> >
> > Kind regards,
> > Waqas.
> >
> >
> > ----- Original Message ----
> > From: Lachele Foley (Lists) <lf.list_at_gmail.com>
> > To: amber_at_scripps.edu
> > Sent: Tuesday, July 8, 2008 7:08:52 PM
> > Subject: Re: AMBER: [amber/glycam] dealing with fucose...
> >
> > Hi Waqas,
> >
> > Before we get off onto a lengthy discussion... You -did- mean 1FA and
> > not F1A, right? The proper name for the residue is 1FA.
> >
> > Also, did you try using our builder online to make your complex? Did
> > you have problems with it? You might find that to be a much easier
> > way to go. If something didn't work, let us know. We have a mailing
> > list you can join when you register. Or send email to
> > glycam_at_gmail.com if you prefer.
> >
> > Also, why do you want a frcmod
> file? If I understand you correctly,
> > you shouldn't need it for this. The parameter and prep files should
> > be all you need (for fucose, that is). You can download the latest
> > versions of the Glycam parameters here:
> >
> > http://www.glycam.com/gl_params.html
> >
> > You want Glycam_06.prep and Glycam_06d.dat. For linking to proteins,
> > you also need the glycam_amino* libraries. The leaprc.Glycam06 might
> > also be useful to you.
> >
> > :-) Lachele
> >
> >
> > On 7/8/08, Waqas Nasir <nasirwaqas1983_at_yahoo.com> wrote:
> > >
> > >
> > >
> > >
> > >
> > > Hi,
> > >
> > > Hope every thing is working fine at your side.
> > >
> > > Well, I am a new user of glycam and amber, just a couple of weeks
> old, and I am trying to do some studies with protein carbohydrate complex.
> > >
> > > The complex
> that I have contains beta-d-galactose and alpha-l-fucose
> with the protein chain (The trisaccharide resides in the binding pocket of the
> protein and is not covalently attached to it).
> > >
> > > With 2 galactoses one can rename them in the pdb file as 1GB and ZGB
> (since one galactose has linkage position 1, and the other one has linkage
> positions 2 and 3) but with fucose I am a bit confused because its not present
> in the standard glycam04 forcefield. I thought of building that residue with
> "biomolecule builder"
> (http://www.glycam.com/CCRC/biombuilder/biomb_index.jsp) but could not find a
> way to generate the prep & frcmod files for F1A (alpha-l-fucose with
> linkage position 1) residue that I need. I tried antechamber as well but there
> I do have some missing parameters.
> > >
> > > What I am trying to do now is to find a way to generate the prep and
> frcmod files for this resiue in order
> to make it recognized in amber, so that I
> could rename this residue in pdb file and then load the whole pdb (with protein
> and carbohydrate) to generate top and crd files.
> > >
> > > I appologize if my language is not that proper or clear. I hope that
> you did understand it. I request you to please let me know if I am on the right
> track or if there is some problem with my understanding of the subject matter.
> > >
> > > I would really appreciate if you could respond.
> > > Wish you and your team all the best!
> > >
> > > Thanks,
> > > Kind regards,
> > > Waqas.
> > >
> > >
> > >
> >
> >
> >
> > --
> > :-) Lachele
> > Lachele Foley
> > CCRC/UGA
> > 2-0263
> > -----------------------------------------------------------------------
> > The AMBER Mail Reflector
> > To post, send mail to amber_at_scripps.edu
> > To
> unsubscribe, send "unsubscribe amber" (in the *body* of the
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> > to majordomo_at_scripps.edu
> >
> >
>
>
>
> --
> :-) Lachele
> Lachele Foley
> CCRC/UGA
> 2-0263
> -----------------------------------------------------------------------
> The AMBER Mail Reflector
> To post, send mail to amber_at_scripps.edu
> To unsubscribe, send "unsubscribe amber" (in the *body* of the email)
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>
>

-- 
:-) Lachele
Lachele Foley
CCRC/UGA
2-0263
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