Müller Peter, Köpke Sinje, Sheldrick George M
UCLA-DOE Laboratory of Structural Biology and Molecular Medicine, 205 MBI, Box 95157, Los Angeles, CA 90095-1570, USA.
Acta Crystallogr D Biol Crystallogr. 2003 Jan;59(Pt 1):32-7. doi: 10.1107/s0907444902018000. Epub 2002 Dec 19.
The proper assignment of metal ions in X-ray structures of proteins is not always easy, but in many cases this knowledge can be important, e.g. for an understanding of enzyme mechanism. In this publication, the bond-valence approach is assessed critically. A simplified version, the calcium bond-valence sum (CBVS), is proposed for the convenient analysis of the geometric environment of potential sites with a view to metal-ion assignment. The bond-valence approach is found to be more reliable for structures determined from high-resolution data (1.5 A or better).
