Le 11 nov. 09 à 13:16, Matthias Zebisch a écrit :
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 anomalousscattering to position chlorides, calcium, sulfate in already phased structures?Thanks in advance, Matthias
Hi Matthias,We collected a highly-redundant sulfur-SAD data set at 2.0 A wavelength. We managed to solve the structure thanks to two of the three sulfur atoms present in the protein, plus one chloride ion that happened to be bound to it. Radiation damage was an issue, but only after anomalous redundancy was higher than 30. With very, very high redundancy it was not possible to solve the structure. Thus, in some cases, it may be worth trying with less images.
Of course, as Fred said, the precission of the measurements is extremely important for sulfur-SAD phasing.
Best, -- Miguel Architecture et Fonction des Macromolécules Biologiques (UMR6098) CNRS, Universités d'Aix-Marseille I & II Case 932, 163 Avenue de Luminy, 13288 Marseille cedex 9, France Tel: +33(0) 491 82 55 93 Fax: +33(0) 491 26 67 20 e-mail: miguel.ortiz-lombar...@afmb.univ-mrs.fr Web: http://www.pangea.org/mol/spip.php?rubrique2
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