1 .TH pdb2gmx 1 "Fri 18 Jan 2013" "" "GROMACS suite, VERSION 4.5.6"
3 pdb2gmx - converts coordinate files to topology and FF-compliant coordinate files
8 .BI "\-f" " eiwit.pdb "
10 .BI "\-p" " topol.top "
11 .BI "\-i" " posre.itp "
12 .BI "\-n" " clean.ndx "
13 .BI "\-q" " clean.pdb "
15 .BI "\-[no]version" ""
17 .BI "\-chainsep" " enum "
18 .BI "\-merge" " enum "
20 .BI "\-water" " enum "
30 .BI "\-angle" " real "
34 .BI "\-[no]missing" ""
36 .BI "\-posrefc" " real "
37 .BI "\-vsite" " enum "
39 .BI "\-[no]deuterate" ""
40 .BI "\-[no]chargegrp" ""
45 \&This program reads a \fB .pdb\fR (or \fB .gro\fR) file, reads
46 \&some database files, adds hydrogens to the molecules and generates
47 \&coordinates in GROMACS (GROMOS), or optionally \fB .pdb\fR, format
48 \&and a topology in GROMACS format.
49 \&These files can subsequently be processed to generate a run input file.
53 \&\fB pdb2gmx\fR will search for force fields by looking for
54 \&a \fB forcefield.itp\fR file in subdirectories \fB forcefield.ff\fR
55 \&of the current working directory and of the GROMACS library directory
56 \&as inferred from the path of the binary or the \fB GMXLIB\fR environment
58 \&By default the forcefield selection is interactive,
59 \&but you can use the \fB \-ff\fR option to specify one of the short names
60 \&in the list on the command line instead. In that case \fB pdb2gmx\fR just looks
61 \&for the corresponding \fB forcefield.ff\fR directory.
65 \&After choosing a force field, all files will be read only from
66 \&the corresponding force field directory.
67 \&If you want to modify or add a residue types, you can copy the force
68 \&field directory from the GROMACS library directory to your current
69 \&working directory. If you want to add new protein residue types,
70 \&you will need to modify \fB residuetypes.dat\fR in the library directory
71 \&or copy the whole library directory to a local directory and set
72 \&the environment variable \fB GMXLIB\fR to the name of that directory.
73 \&Check Chapter 5 of the manual for more information about file formats.
77 \&Note that a \fB .pdb\fR file is nothing more than a file format, and it
78 \&need not necessarily contain a protein structure. Every kind of
79 \&molecule for which there is support in the database can be converted.
80 \&If there is no support in the database, you can add it yourself.
83 \&The program has limited intelligence, it reads a number of database
84 \&files, that allow it to make special bonds (Cys\-Cys, Heme\-His, etc.),
85 \&if necessary this can be done manually. The program can prompt the
86 \&user to select which kind of LYS, ASP, GLU, CYS or HIS residue is
87 \&desired. For Lys the choice is between neutral (two protons on NZ) or
88 \&protonated (three protons, default), for Asp and Glu unprotonated
89 \&(default) or protonated, for His the proton can be either on ND1,
90 \&on NE2 or on both. By default these selections are done automatically.
91 \&For His, this is based on an optimal hydrogen bonding
92 \&conformation. Hydrogen bonds are defined based on a simple geometric
93 \&criterion, specified by the maximum hydrogen\-donor\-acceptor angle
94 \&and donor\-acceptor distance, which are set by \fB \-angle\fR and
95 \&\fB \-dist\fR respectively.
98 \&The protonation state of N\- and C\-termini can be chosen interactively
99 \&with the \fB \-ter\fR flag. Default termini are ionized (NH3+ and COO\-),
100 \&respectively. Some force fields support zwitterionic forms for chains of
101 \&one residue, but for polypeptides these options should NOT be selected.
102 \&The AMBER force fields have unique forms for the terminal residues,
103 \&and these are incompatible with the \fB \-ter\fR mechanism. You need
104 \&to prefix your N\- or C\-terminal residue names with "N" or "C"
105 \&respectively to use these forms, making sure you preserve the format
106 \&of the coordinate file. Alternatively, use named terminating residues
110 \&The separation of chains is not entirely trivial since the markup
111 \&in user\-generated PDB files frequently varies and sometimes it
112 \&is desirable to merge entries across a TER record, for instance
113 \&if you want a disulfide bridge or distance restraints between
114 \&two protein chains or if you have a HEME group bound to a protein.
115 \&In such cases multiple chains should be contained in a single
116 \&\fB moleculetype\fR definition.
117 \&To handle this, \fB pdb2gmx\fR uses two separate options.
118 \&First, \fB \-chainsep\fR allows you to choose when a new chemical chain should
119 \&start, and termini added when applicable. This can be done based on the
120 \&existence of TER records, when the chain id changes, or combinations of either
121 \&or both of these. You can also do the selection fully interactively.
122 \&In addition, there is a \fB \-merge\fR option that controls how multiple chains
123 \&are merged into one moleculetype, after adding all the chemical termini (or not).
124 \&This can be turned off (no merging), all non\-water chains can be merged into a
125 \&single molecule, or the selection can be done interactively.
128 \&\fB pdb2gmx\fR will also check the occupancy field of the \fB .pdb\fR file.
129 \&If any of the occupancies are not one, indicating that the atom is
130 \¬ resolved well in the structure, a warning message is issued.
131 \&When a \fB .pdb\fR file does not originate from an X\-ray structure determination
132 \&all occupancy fields may be zero. Either way, it is up to the user
133 \&to verify the correctness of the input data (read the article!).
136 \&During processing the atoms will be reordered according to GROMACS
137 \&conventions. With \fB \-n\fR an index file can be generated that
138 \&contains one group reordered in the same way. This allows you to
139 \&convert a GROMOS trajectory and coordinate file to GROMOS. There is
140 \&one limitation: reordering is done after the hydrogens are stripped
141 \&from the input and before new hydrogens are added. This means that
142 \&you should not use \fB \-ignh\fR.
145 \&The \fB .gro\fR and \fB .g96\fR file formats do not support chain
146 \&identifiers. Therefore it is useful to enter a \fB .pdb\fR file name at
147 \&the \fB \-o\fR option when you want to convert a multi\-chain \fB .pdb\fR file.
151 \&The option \fB \-vsite\fR removes hydrogen and fast improper dihedral
152 \&motions. Angular and out\-of\-plane motions can be removed by changing
153 \&hydrogens into virtual sites and fixing angles, which fixes their
154 \&position relative to neighboring atoms. Additionally, all atoms in the
155 \&aromatic rings of the standard amino acids (i.e. PHE, TRP, TYR and HIS)
156 \&can be converted into virtual sites, eliminating the fast improper dihedral
157 \&fluctuations in these rings. \fB Note\fR that in this case all other hydrogen
158 \&atoms are also converted to virtual sites. The mass of all atoms that are
159 \&converted into virtual sites, is added to the heavy atoms.
162 \&Also slowing down of dihedral motion can be done with \fB \-heavyh\fR
163 \&done by increasing the hydrogen\-mass by a factor of 4. This is also
164 \&done for water hydrogens to slow down the rotational motion of water.
165 \&The increase in mass of the hydrogens is subtracted from the bonded
166 \&(heavy) atom so that the total mass of the system remains the same.
168 .BI "\-f" " eiwit.pdb"
170 Structure file: gro g96 pdb tpr etc.
172 .BI "\-o" " conf.gro"
174 Structure file: gro g96 pdb etc.
176 .BI "\-p" " topol.top"
180 .BI "\-i" " posre.itp"
182 Include file for topology
184 .BI "\-n" " clean.ndx"
188 .BI "\-q" " clean.pdb"
190 Structure file: gro g96 pdb etc.
194 Print help info and quit
196 .BI "\-[no]version" "no "
197 Print version info and quit
199 .BI "\-nice" " int" " 0"
202 .BI "\-chainsep" " enum" " id_or_ter"
203 Condition in PDB files when a new chain should be started (adding termini): \fB id_or_ter\fR, \fB id_and_ter\fR, \fB ter\fR, \fB id\fR or \fB interactive\fR
205 .BI "\-merge" " enum" " no"
206 Merge multiple chains into a single [moleculetype]: \fB no\fR, \fB all\fR or \fB interactive\fR
208 .BI "\-ff" " string" " select"
209 Force field, interactive by default. Use \fB \-h\fR for information.
211 .BI "\-water" " enum" " select"
212 Water model to use: \fB select\fR, \fB none\fR, \fB spc\fR, \fB spce\fR, \fB tip3p\fR, \fB tip4p\fR or \fB tip5p\fR
214 .BI "\-[no]inter" "no "
215 Set the next 8 options to interactive
218 Interactive SS bridge selection
220 .BI "\-[no]ter" "no "
221 Interactive termini selection, instead of charged (default)
223 .BI "\-[no]lys" "no "
224 Interactive lysine selection, instead of charged
226 .BI "\-[no]arg" "no "
227 Interactive arginine selection, instead of charged
229 .BI "\-[no]asp" "no "
230 Interactive aspartic acid selection, instead of charged
232 .BI "\-[no]glu" "no "
233 Interactive glutamic acid selection, instead of charged
235 .BI "\-[no]gln" "no "
236 Interactive glutamine selection, instead of neutral
238 .BI "\-[no]his" "no "
239 Interactive histidine selection, instead of checking H\-bonds
241 .BI "\-angle" " real" " 135 "
242 Minimum hydrogen\-donor\-acceptor angle for a H\-bond (degrees)
244 .BI "\-dist" " real" " 0.3 "
245 Maximum donor\-acceptor distance for a H\-bond (nm)
247 .BI "\-[no]una" "no "
248 Select aromatic rings with united CH atoms on phenylalanine, tryptophane and tyrosine
250 .BI "\-[no]ignh" "no "
251 Ignore hydrogen atoms that are in the coordinate file
253 .BI "\-[no]missing" "no "
254 Continue when atoms are missing, dangerous
257 Be slightly more verbose in messages
259 .BI "\-posrefc" " real" " 1000 "
260 Force constant for position restraints
262 .BI "\-vsite" " enum" " none"
263 Convert atoms to virtual sites: \fB none\fR, \fB hydrogens\fR or \fB aromatics\fR
265 .BI "\-[no]heavyh" "no "
266 Make hydrogen atoms heavy
268 .BI "\-[no]deuterate" "no "
269 Change the mass of hydrogens to 2 amu
271 .BI "\-[no]chargegrp" "yes "
272 Use charge groups in the \fB .rtp\fR file
274 .BI "\-[no]cmap" "yes "
275 Use cmap torsions (if enabled in the \fB .rtp\fR file)
277 .BI "\-[no]renum" "no "
278 Renumber the residues consecutively in the output
280 .BI "\-[no]rtpres" "no "
281 Use \fB .rtp\fR entry names as residue names
286 More information about \fBGROMACS\fR is available at <\fIhttp://www.gromacs.org/\fR>.