Closed BJWiley233 closed 1 year ago
Hi Brian, I'm actually surprised you got that close... since Tinker's PDBXYZ is not set up to handle phosphorylated residues. As you say, it looks like there are two bonds where the connectivity is only one direction (ie, atom A is connected to atom B, but not the other way around). I'm guessing this might be due to the presence of the phosphates (?). Does PDBXYZ work completely correctly if you convert the PDB file of the protein without the phosphates? That said, your best option might be to just add the couple of missing bond connectivities to the XYZ file "manually".
Yes I realized I could only get as far as running xyzedit
on the files after manually adding the connections. Realized tinker won't run any analysis on these files since the atom names are the PDB file atom names if you have a phosphorylated serine or any phosphorylated residues. Thanks for confirming. Any work coming down the pike for adding phosphorylated residues?
Unfortunately, not that I know of at this time. There are two issues. First, we would have to extend the code for PDBXYZ, XYZPDB, etc. to know about and handle phosphorylated amino acids. This would be a bit of a pain if done "correctly", but not too terrible. The second, and perhaps bigger, issue would be getting good parameters for the modified amino acids in AMOEBA or whatever force field you want to use. I believe (not sure?) that none of the standard simpler force fields such as CHARMM, Amber and OPLS have standard or built-in parameters for phosphoamino acids. I know AMOEBA does not. Again, this would be a small, but nontrivial, research project to do this right.
Hi,
I am hoping to run minimization and MD on a phoshorylated ERK structure I created using 2 singly phosphorylated serines on a model I threaded. I can run
pdbxyz
correctly using theSEP
residue name, theO1P/O2P
atoms are created in the xyz file, but oddly despite most of theCA
atom have all four bonds including theHA
atom except near the end of the molecule or even the nextC
in the peptide bond won't have an atom connection to the previousCA
atom. Examples below and PDB file attached.EDIT: it seems to be non-specific the type of connections that are missing after I test a few more times so the below is just type of bond missing.
Latter
C
in next residue missing connection to previousCA
. Atom 4968 should connect back to 4953.