1 .TH g_sas 1 "Fri 18 Jan 2013" "" "GROMACS suite, VERSION 4.5.6"
3 g_sas - computes solvent accessible surface area
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
35 \&accessible surface area. See Eisenhaber F, Lijnzaad P, Argos P,
36 \&Sander C, & Scharf M (1995) J. Comput. Chem. 16, 273\-284.
37 \&As a side effect, the Connolly surface can be generated as well in
38 \&a \fB .pdb\fR file where the nodes are represented as atoms and the
39 \&vertice connecting the nearest nodes as CONECT records.
40 \&The program will ask for a group for the surface calculation
41 \&and a group for the output. The calculation group should always
42 \&consists of all the non\-solvent atoms in the system.
43 \&The output group can be the whole or part of the calculation group.
44 \&The average and standard deviation of the area over the trajectory can be plotted
45 \&per residue and atom as well (options \fB \-or\fR and \fB \-oa\fR).
46 \&In combination with the latter option an \fB .itp\fR file can be
47 \&generated (option \fB \-i\fR)
48 \&which can be used to restrain surface atoms.
51 \&By default, periodic boundary conditions are taken into account,
52 \&this can be turned off using the \fB \-nopbc\fR option.
55 \&With the \fB \-tv\fR option the total volume and density of the
56 \&molecule can be computed.
57 \&Please consider whether the normal probe radius is appropriate
58 \&in this case or whether you would rather use e.g. 0. It is good
59 \&to keep in mind that the results for volume and density are very
60 \&approximate. For example, in ice Ih, one can easily fit water molecules in the
61 \&pores which would yield a volume that is too low, and surface area and density
62 \&that are both too high.
66 Trajectory: xtc trr trj gro g96 pdb cpt
68 .BI "\-s" " topol.tpr"
70 Structure+mass(db): tpr tpb tpa gro g96 pdb
76 .BI "\-or" " resarea.xvg"
80 .BI "\-oa" " atomarea.xvg"
84 .BI "\-tv" " volume.xvg"
88 .BI "\-q" " connelly.pdb"
90 Protein data bank file
92 .BI "\-n" " index.ndx"
96 .BI "\-i" " surfat.itp"
98 Include file for topology
102 Print help info and quit
104 .BI "\-[no]version" "no "
105 Print version info and quit
107 .BI "\-nice" " int" " 19"
110 .BI "\-b" " time" " 0 "
111 First frame (ps) to read from trajectory
113 .BI "\-e" " time" " 0 "
114 Last frame (ps) to read from trajectory
116 .BI "\-dt" " time" " 0 "
117 Only use frame when t MOD dt = first time (ps)
120 View output \fB .xvg\fR, \fB .xpm\fR, \fB .eps\fR and \fB .pdb\fR files
122 .BI "\-xvg" " enum" " xmgrace"
123 xvg plot formatting: \fB xmgrace\fR, \fB xmgr\fR or \fB none\fR
125 .BI "\-probe" " real" " 0.14 "
126 Radius of the solvent probe (nm)
128 .BI "\-ndots" " int" " 24"
129 Number of dots per sphere, more dots means more accuracy
131 .BI "\-qmax" " real" " 0.2 "
132 The maximum charge (e, absolute value) of a hydrophobic atom
134 .BI "\-[no]f_index" "no "
135 Determine from a group in the index file what are the hydrophobic atoms rather than from the charge
137 .BI "\-minarea" " real" " 0.5 "
138 The minimum area (nm2) to count an atom as a surface atom when writing a position restraint file (see help)
140 .BI "\-[no]pbc" "yes "
141 Take periodicity into account
143 .BI "\-[no]prot" "yes "
144 Output the protein to the Connelly \fB .pdb\fR file too
146 .BI "\-dgs" " real" " 0 "
147 Default value for solvation free energy per area (kJ/mol/nm2)
152 More information about \fBGROMACS\fR is available at <\fIhttp://www.gromacs.org/\fR>.