[gmx-users] gmx sasa for protein-ligand complex(problem with command usage)

[Archana Sonawani-Jagtap]

Dear Gromacs Users,

I have GPCR-protein complex simulation and want to calculate buried surface
area  of the complex. I am using gmx sasa but facing problem in using the
command especially the -output part.

I need to calculate SASA for unbound receptor,unbound ligand and of
complex. I have made index file where complex is ofcourse group 1 Protein
and receptor is group 24 and ligand is group 25

when I provide the following command I gt TOTAL SASA
gmx sasa -f .xtc -s .tpr -o bound-sasa.xvg -tu ns -n .ndx -surface 'group
"1"'

but when I add the output part
-output '"hydrophobic" group "1" and charge {-0.2 to 02}; "hydrophilic"
group "1" and not charge {-0.2 to 0.2};

Error in user input:
Selection '"hydrophilic" group "1" and not charge {-0.2 to 0.2}' never
matches
any atoms.

Can anyone tell me how to get SASA for receptor, ligand and compex.


Thanks

Archana