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Dear Shun, One alternative may be to use the lanthanide complexes developed by R. Khan and E Girard at the IBS. They are smaller, so they may induce less constraint in your crystals, and they give a strong anomalous signal. You can get them from several places, such as http://www.natx-ray.com/products/catalogue_consum_CSM002.html Regards JL On 21/10/2015 06:19, Shun Liu wrote: > Dear CCP4 colleagues, > > We are working on a Ta6Br14 cluster-SAD dataset (4.3 angstroms) with lattice-translocation disorder (with a total Rmerge of 0.16). Both SHELXC and Xtriage gave the similar positive result about the anomalous signal (See below). > > ------------------------------------------------------------------------------------------------- > Resl. Inf. 9.58 7.61 6.65 6.04 5.61 5.27 5.01 4.79 4.61 4.45 4.31 > N(data) 1427 1410 1410 1409 1385 1452 1367 1399 1367 1395 1385 > <I/sig> 76.3 52.1 26.7 13.7 8.7 6.1 5.1 5.0 3.9 2.7 1.8 > %Complete 98.8 99.9 100.0 99.9 100.0 100.0 100.0 99.9 99.7 99.6 95.8 > <d"/sig> 11.67 9.67 6.12 3.73 2.50 1.59 1.21 0.99 0.84 0.79 0.68 > ------------------------------------------------------------------------------------------------ > unused: - 49.7669 [ 0/29 ] > bin 1: 49.7669 - 9.2629 [3086/3100] 0.8212 > bin 2: 9.2629 - 7.3599 [3031/3031] 0.7689 > bin 3: 7.3599 - 6.4318 [3073/3073] 0.5380 > bin 4: 6.4318 - 5.8447 [3071/3075] 0.2933 > bin 5: 5.8447 - 5.4263 [3054/3054] 0.1230 > bin 6: 5.4263 - 5.1067 [3070/3071] 0.0363 > bin 7: 5.1067 - 4.8512 [3038/3039] 0.0126 > bin 8: 4.8512 - 4.6402 [3028/3048] 0.0074 > bin 9: 4.6402 - 4.4617 [2955/3037] 0.0021 > bin 10: 4.4617 - 4.3078 [2730/3059] 0.0000 > unused: 4.3078 - [ 0/0 ] > -------------------------------------------------------------------------------------------------- > The Tantalum sites and the initial map seem ambiguous, with which automatic model-building failed. > I am wondering whether the lattice-translocation disorder of the dataset impacts the reliability of the anomalous signal, tantalum sites and the initial map. If it does, how can we decrease its impact? If it doesn't, is it possible to find the accurate Ta sites and generate an interpretable map suitable for model-building with this dataset? (After all, it has been reported that Ta sites can be found at 6A resolution.) > > Any suggestion and comment will be highly appreciated! > > Best, > Shun > > -- -------------------------------- Jean-Luc Ferrer Institut de Biologie Structurale 71 Avenue des Martyrs CS 10090 38044 Grenoble Cedex 9 - FRANCE Ph.: +33 (0)4 57 42 85 22 Fax: +33 (0)4 76 50 63 14 --------------------------------