1 .TH g_sas 1 "Mon 4 Apr 2011" "" "GROMACS suite, VERSION 4.5.4-dev-20110404-bc5695c"
3 g_sas - computes solvent accessible surface area
5 .B VERSION 4.5.4-dev-20110404-bc5695c
9 .BI "\-s" " topol.tpr "
10 .BI "\-o" " area.xvg "
11 .BI "\-or" " resarea.xvg "
12 .BI "\-oa" " atomarea.xvg "
13 .BI "\-tv" " volume.xvg "
14 .BI "\-q" " connelly.pdb "
15 .BI "\-n" " index.ndx "
16 .BI "\-i" " surfat.itp "
18 .BI "\-[no]version" ""
25 .BI "\-probe" " real "
28 .BI "\-[no]f_index" ""
29 .BI "\-minarea" " real "
34 \&\fB g_sas\fR computes hydrophobic, hydrophilic and total solvent accessible surface area.
35 \&As a side effect, the Connolly surface can be generated as well in
36 \&a \fB .pdb\fR file where the nodes are represented as atoms and the vertices
37 \&connecting the nearest nodes as CONECT records.
38 \&The program will ask for a group for the surface calculation
39 \&and a group for the output. The calculation group should always
40 \&consists of all the non\-solvent atoms in the system.
41 \&The output group can be the whole or part of the calculation group.
42 \&The average and standard deviation of the area over the trajectory can be plotted
43 \&per residue and atom as well (options \fB \-or\fR and \fB \-oa\fR).
44 \&In combination with the latter option an \fB .itp\fR file can be
45 \&generated (option \fB \-i\fR)
46 \&which can be used to restrain surface atoms.
49 \&By default, periodic boundary conditions are taken into account,
50 \&this can be turned off using the \fB \-nopbc\fR option.
53 \&With the \fB \-tv\fR option the total volume and density of the molecule can be
55 \&Please consider whether the normal probe radius is appropriate
56 \&in this case or whether you would rather use e.g. 0. It is good
57 \&to keep in mind that the results for volume and density are very
58 \&approximate. For example, in ice Ih, one can easily fit water molecules in the
59 \&pores which would yield a volume that is too low, and surface area and density
60 \&that are both too high.
64 Trajectory: xtc trr trj gro g96 pdb cpt
66 .BI "\-s" " topol.tpr"
68 Structure+mass(db): tpr tpb tpa gro g96 pdb
74 .BI "\-or" " resarea.xvg"
78 .BI "\-oa" " atomarea.xvg"
82 .BI "\-tv" " volume.xvg"
86 .BI "\-q" " connelly.pdb"
88 Protein data bank file
90 .BI "\-n" " index.ndx"
94 .BI "\-i" " surfat.itp"
96 Include file for topology
100 Print help info and quit
102 .BI "\-[no]version" "no "
103 Print version info and quit
105 .BI "\-nice" " int" " 19"
108 .BI "\-b" " time" " 0 "
109 First frame (ps) to read from trajectory
111 .BI "\-e" " time" " 0 "
112 Last frame (ps) to read from trajectory
114 .BI "\-dt" " time" " 0 "
115 Only use frame when t MOD dt = first time (ps)
118 View output \fB .xvg\fR, \fB .xpm\fR, \fB .eps\fR and \fB .pdb\fR files
120 .BI "\-xvg" " enum" " xmgrace"
121 xvg plot formatting: \fB xmgrace\fR, \fB xmgr\fR or \fB none\fR
123 .BI "\-probe" " real" " 0.14 "
124 Radius of the solvent probe (nm)
126 .BI "\-ndots" " int" " 24"
127 Number of dots per sphere, more dots means more accuracy
129 .BI "\-qmax" " real" " 0.2 "
130 The maximum charge (e, absolute value) of a hydrophobic atom
132 .BI "\-[no]f_index" "no "
133 Determine from a group in the index file what are the hydrophobic atoms rather than from the charge
135 .BI "\-minarea" " real" " 0.5 "
136 The minimum area (nm2) to count an atom as a surface atom when writing a position restraint file (see help)
138 .BI "\-[no]pbc" "yes "
139 Take periodicity into account
141 .BI "\-[no]prot" "yes "
142 Output the protein to the Connelly \fB .pdb\fR file too
144 .BI "\-dgs" " real" " 0 "
145 Default value for solvation free energy per area (kJ/mol/nm2)
150 More information about \fBGROMACS\fR is available at <\fIhttp://www.gromacs.org/\fR>.