Tables for
Volume F
Crystallography of biological macromolecules
Edited by E. Arnold, D. M. Himmel and M. G. Rossmann

International Tables for Crystallography (2012). Vol. F, ch. 18.6, p. 517   | 1 | 2 |

Section 18.6.10. Conclusions

A. T. Brunger,a* P. D. Adams,b W. L. DeLano,c P. Gros,d R. W. Grosse-Kunstleve,b J.-S. Jiang,e N. S. Pannu,f R. J. Read,g L. M. Riceh and T. Simonsoni

aHoward Hughes Medical Institute, and Departments of Molecular and Cellular Physiology, Neurology and Neurological Sciences, and Stanford Synchrotron Radiation Laboratory (SSRL), Stanford University, 1201 Welch Road, MSLS P210, Stanford, CA 94305, USA,bThe Howard Hughes Medical Institute and Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA,cGraduate Group in Biophysics, Box 0448, University of California, San Francisco, CA 94143, USA,dCrystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands,eProtein Data Bank, Biology Department, Brookhaven National Laboratory, Upton, NY 11973–5000, USA,fDepartment of Mathematical Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2G1,gDepartment of Haematology, University of Cambridge, Wellcome Trust Centre for Molecular Mechanisms in Disease, CIMR, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, England,hDepartment of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA, and iLaboratoire de Biologie Structurale (CNRS), IGBMC, 1 rue Laurent Fries, 67404 Illkirch (CU de Strasbourg), France
Correspondence e-mail:

18.6.10. Conclusions

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CNS is a general system for structure determination by X-ray crystallography and solution NMR. It covers the whole spectrum of methods used to solve X-ray or solution NMR structures. The multi-layer architecture allows use of the system with different levels of expertise. The HTML interface allows the novice to perform standard tasks. The interface provides a convenient means of editing complicated task files, even for the expert (Fig.[link]). This graphical interface makes it less likely that an important parameter will be overlooked when editing the file. In addition, the graphical interface can be used with any task file, not just the standard distributed ones. HTML-based documentation and graphical output are planned in the future.

Most operations within a crystallographic algorithm are defined through modules and task files. This allows for the development of new algorithms and for existing algorithms to be precisely defined and easily modified without the need for source-code modifications.

The hierarchical structure of CNS allows extensive testing at each level. For example, once the source code and CNS basic commands have been tested, testing of the modules and task files is performed. A test suite consisting of more than a hundred test cases is frequently evaluated during CNS development in order to detect and correct programming errors. Furthermore, this suite is run on several hardware platforms in order to detect any machine-specific errors. This testing scheme makes CNS highly reliable.

Algorithms can be readily understood by inspecting the modules or task files. This self-documenting feature of the modules provides a powerful teaching tool. Users can easily interpret an algorithm and compare it with published methods in the literature. To our knowledge, CNS is the only system that enables one to define symbolically any target function for a broad range of applications, from heavy-atom phasing or molecular-replacement searches to atomic resolution refinement.


Stout, G. H. & Jensen, L. H. (1989). X-ray Structure Determination, p. 33. New York: Wiley Interscience.Google Scholar

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