[gmx-users] amide-capped C-terminus; OPLS force field

[Sahil Lall]

Dear all, 

Does anyone have any experience with capping C-terminal amino acid
residues in the OPLS force field? What atomtypes should I use to
maintain neutrality of the system? 

eg. If i have a cystine at the C-terminus residue, and I use the
following atomtypes 

N          opls_238      -0.5
H          opls_241       0.3
CA        opls_224B     0.14
HA        opls_140       0.06
CB        opls_214       0.0975
HB1      opls_140       0.06
HB2      opls_140       0.06
SG        opls_203      -0.2175
C          opls_235        0.5
O          opls_236      -0.5
NT        opls_900      -0.9
H1        opls_909       0.36
H2        opls_909       0.36 

The system has a -0.18 qtotal (overall charge). Any help is appreciated.


Regards, 

Sahil