# GRO, GROUP

NAME
GRO, GROUP - group structures: catch more than one structure.
SYNOPSIS
GRO identifier1 identifier2 ... identifierN
GRO ALL
GRO SAV filename
GRO SSC filename
GROUP identifier1 identifier2 ... identifierN
GROUP ALL
GROUP SAVE filename
GROUP SSC filename
DESCRIPTION
The command GROUP may be used to catch more than one structure. It is possible to group only one structure, but this doesn't make much sense. A typical usage will be to unite some inhibitor with a substrate.
The structures which form the group will be rotated about the common rotation axis and translated as a single object, except it the keyword ALL is used. In that case, each structure will retain its own rotation center (the old one).
Slab and color fading will be changed simultaneously for all structures. It is recommended to adjust slab and color fading before forming the group. Use much wider slab than usual!
Many other commands will be applied simultaneously for all structures (color, BACKBONE etc.). The exceptions are SAVE , EDIT and REPLACE , which use only default structure (the one which was caught last or loaded as the last structure).
To break the group of structures, i.e. to cancel the command GROUP, execute the command CATCH with a single identifier as a command parameter, to catch only one structure. The command DISCARD may also be used to break the group of structures. Two other commands which cancel GROUP are CREATE and LOAD .
GROUP ALL
The keyword ALL may be used to group all structures into a single object. Each structure will retain its old rotation center. To break the group, use the command CATCH to catch only one structure.
GROUP SAVE filename
The keyword SAVE may be used to save the entire group as a single file. Each structure will be stored as a separate chain. If any of the structures contained more than one chain, it will be stored as a single chain. The first structure will be stored as the chain A, the second as the chain B etc. If there are more than 26 structures, some chain identifiers may be used more than once. The original chain identifiers will be lost. The original atomic serial numbers and residue serial numbers will be replaced by new serials. These changes will affect only data stored to the output file. After breaking the group, each structure will remain intact. The file name is case sensitive.
GROUP SSC filename
The keyword SSC may be used to save the entire group into a single file. All structures will be stored as a single chain. The original chain identifiers will be lost. The original atomic serial numbers and residue serial numbers will be replaced by new serials. These changes will affect only data stored to the output file. After breaking the group, each structure will remain intact. The file name is case sensitive.
EXAMPLES

COMMAND | DESCRIPTION
gro 1 2 4 | Group structures 1, 2 and 4. Define a single rotation center for all structures.
gro all | Group all structures. Each structure will retain its old rotation center.
group 1 3 group save united.pdb | Group structures 1 and 3 and store as a single structure consisting of two chains to the output file united.pdb .
gro 2 5 gro ssc xyz.pdb | Group structures 2 and 5 and store as a single chain to the output file called xyz.pdb .

RELATED COMMANDS
CATCH is used to catch only one structure. The command CATCH breaks the group formed by the command GROUP.