2.29 Angstrom is an excellent wavelength for Cl, Ca and S anomalous scatterers. This is the wavelength produced by a Cr home source. Some older references:
Acta Crystallogr D Biol Crystallogr. 2003 Nov;59(Pt 11):1943-57. Epub 2003 Oct 23. Away from the edge: SAD phasing from the sulfur anomalous signal measured in-house with chromium radiation. Acta Crystallogr D Biol Crystallogr. 2005 Jul;61(Pt 7):960-6. Epub 2005 Jun 24. Away from the edge II: in-house Se-SAS phasing with chromium radiation. Acta Crystallogr D Biol Crystallogr. 2005 Aug;61(Pt 8):1013-21. Epub 2005 Jul 20. Structure determination of a novel protein by sulfur SAD using chromium radiation in combination with a new crystal-mounting method. I'm sure there are several structures done with Cr radiation since the above articles were published. Does any body else want to chime in? Jim -----Original Message----- From: CCP4 bulletin board [mailto:[email protected]] On Behalf Of Matthias Zebisch Sent: Wednesday, November 11, 2009 6:16 AM To: [email protected] Subject: [ccp4bb] sulfur sad phasing Dear bb! What is the optimal wavelength for Sulfur SAD phasing? Is it 1.9A or should one go below that to reduce absorption/damage. Also, would the same wavelength be appropriate to maximize anomalous scattering to position chlorides, calcium, sulfate in already phased structures? Thanks in advance, Matthias
