Hi Carlos,
Thank you so much for the quick response. I just want to clarify if what I understand is right.
So to build my modified peptide sequence in tleap, I'd type the following command (AA stands for amino acid)
peptide = sequence {ACE TRP AA2 AA3 ... LYS NHE } ?
The ACE TRP would give me acetylated Trp on the N-terminal and LYS NHE would give me amidated Lys on the C-terminal? Is that correct?
I forgot to mention that I'm doing a peptide simulation using the guidelines from this tutorial on AMBER
https://ambermd.org/tutorials/basic/tutorial0/index.php#Solvate_alanine_dipeptide
Simple Simulation of Alanine Dipeptide - AMBER<
https://ambermd.org/tutorials/basic/tutorial0/index.php#Solvate_alanine_dipeptide>
In order to run a molecular dynamics simulation, we need to load a force field to describe the potential energy of alanine dipeptide. We will use the AMBER force field FF19SB1 for proteins. To learn more about force fields, please look through section 3.1.1 on page 36 of the Amber 2020 Manual.. 5.
ambermd.org
I don't really see where my pdb file could be used in the entire process.
But I'm wondering if I could use the command peptide = loadpdb "my peptide pdb file" to use it for the next steps in the tutorial, e.g. solvation, creating prmtop and rst files, etc.
Thank you.
Yen Nguyen
Graduate Research Assistant
George Mason University
Department of Chemistry and Biochemistry
________________________________
From: Carlos Simmerling <carlos.simmerling.gmail.com>
Sent: Thursday, November 18, 2021 2:55 PM
To: AMBER Mailing List <amber.ambermd.org>
Subject: Re: [AMBER] How to add an amidated residue at the C-terminal in AMBER tleap ?
I think you're looking for the "NHE" residue.
it should work ok if your pdb file has the matching residue and atom names.
if not, you can rename them following the info below:
NHE INT 1
NH2 ENDING GROUP
4 N N M 3 2 1 1.335 116.600 180.000 -0.46300
5 HN1 H E 4 3 2 1.010 119.800 0.000 0.23150
6 HN2 H E 4 3 2 1.010 119.800 180.000 0.23150
On Thu, Nov 18, 2021 at 2:48 PM Yen Nguyen <ynguyen3.gmu.edu> wrote:
> Hello,
> I've been searching for a way to build a peptide sequence with C and N
> terminal modifications (C -terminal = amidated Lys, N-terminal = acetylated
> Trp in tleap (AMBER), but I couldn't find a way to make/add an amidated Lys
> residue at the C-terminal. AMBER has the code ACE for acetylated residues,
> but I don't know if it has a code for amide terminals?
> I'm using amber 18 and the protein forcefield leaprc.protein.ff14SBonlysc
> , which has the following parameter files
> /amber20/dat/leap/parm/parm10.dat
> frcmod.ff14SB
> frcmod.ff99SB14
> I have a pdb file of the peptide, but it looks like AMBER doesn't utilize
> pdb files to create prmtop and coordinate files for my peptide.
> I'd greatly appreciate any help. Thank you!
>
> Yen Nguyen
> Graduate Research Assistant
> George Mason University
> Department of Chemistry and Biochemistry
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Received on Thu Nov 18 2021 - 12:30:02 PST
