GLOBSYMM
GLOBSYMM performs a global search of the quaternary structure of a symmetric oligomer built from identical monomers (point symmetries Pnk, where n = 2...6, and k = 1, 2 are supported). Rotation of a monomer by the Euler angles Alpha, Beta, Gamma followed by its displacement by the vector r and generation of all symmetry mates permits one to construct an arbitrary symmetric oligomer.
The theoretical scattering pattern I(s) of oligomer is expressed using spherical harmonics from the partial scattering amplitudes of a single subunit Alm(s)in the current position/orientation and taking into account the symmetry rules. The subunit's amplitudes in arbitrary arrangement depend on its scattering amplitudes in the reference positions and on three rotational and three translational parameters. The reference partial scattering amplitudes of the subunits have to be precomputed by the program CRYSOL.
An exhaustive grid search of the quaternary structury of the oligomer is performed in GLOBSYMM exploiting the fact that an arbitrary model can be described by up to max six rotatranslational parameters (only four for Pn). These parameters are optimized to minimize discrepancy between the calculated curve and the experimental data while avoiding disconnected configurations and those with steric clashes. Eventual information on the multimerization interfaces (in terms of contacting residues) can also be taken into account.
Please refer to the paper cited above for further details about the implemented algorithm.
Running GLOBSYMM
Interactive Configuration
Modelling with GLOBSYMM is done in interactive dialog mode. Retrieval of non-best solutions is performed from the command line.
globsymm LOGFILE SOLUTION
