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MIRAS/SIRAS Approach

 

In this section it is described how to use the Grafical User Interface to set up a new MIRAS/SIRAS project. The user has to fill the following forms named:

 

The following buttons are used to set the default values or to apply the changes to the fields of the form. By clicking on quit button the project will be abandoned and the main window will be displayed. To access the next form, if some changes have been introduced, it is necessary to click on Apply.


General

In this form some information are displayed such as the Configuration directory, the User working directory and the Project name.
The user can supply a Job title for this project.


MTZ File

This form is used to get all the information  from an MTZ file. Once browsed, it is possible to view a short summary of the MTZ file.
For ab-initio only F and Sigma(F) are necessary; these two columns must be added from available columns.

If necessary it is possible to specify a different space group. The user can just write the new symbol or to select it from a list.


On the bottom of this form information about symmetry and reflections is diplayed.
 


Cell Content

This form is used to supply the cell content. It is possible to specify the number of molecules in asymmetric unit.
The chemical content can be specified trough the weight or the number of residues or the sequence (in FASTA format);
the sequence can be stored in a file or pasted directly in the right part of the form.
Atoms external to the residues (ligands, heavy atoms, ...) should be added to make the structure solution simpler.
Some useful information is shown in the output window at the bottom of the form.


Tasks

The strategy for the structure solution is defined in this form. The recommended procedure is the Patterson one as alternative to Tangent Formula. It is possible to define the number of trials divided in a number of blocks. Anyway robust defaults are supplied.
If non-atomic resolution data are available, it is possible to generate and use extrapolated reflections to increase the power of the algorithms to solve the structure.
It is also possible to use extrapolated reflections for final map improving only.

By clicking on Apply button, the ab-initio straucture solution process will start.


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