SFCHECK Alexei Vagin YSBL, Chemistry Department, University of York

SFCHECK Sfcheck can: 1.Check experimental data 1.Anisotroy 2.Pseudo translation 3.Completeness (Overall, radial and angular) 4.Twinning 5.etc 2.Check final model vs experimental data 1.Agreement with experimental data 2.Residue by residue fit to electron density 3.Complete omit map

SFCHECK Usage: sfcheck -f or sfcheck -f -m data - experimental data. They can be X-ray diffraction data or electron density (for electron microscopy)

Sfcheck 1

Sfcheck 2

Analysis of a model Fit a given model into electron density is characterised by several indicators 1)Density index 2)Density correlation 3)Connectivity index If omit map was asked then all indicators are calculated using this map.

SFCHECK It is a useful program currently underused. Users sometimes forced to use command line option. I think we need a separate sfcheck option in the ccp4 interface. We use it in BALBES to analyse experimental data and to make decisions (use of pseudo-translation, optimal resolution for molecular replacement etc) accordingly. At the end SFCHECK is used to analyse fit to experimental data. All necessary info are written in an xml format and they are read by BALBES.