Dear all, I'm working on a 18kD protein, the secondary structure prediction says most of the structure is beta sheets, trying to solve the structure with SAD. Heavy atom soaking gives several datasets with I, W, Au, range from 2.7~3.7A, however, the anomalous signal is pretty weak, I couldn't find a reasonable solution. We got a co-crystal dataset with the magic triangle I3C, extends to around 2.5A, this is the best data we got so far. shelxc gives me the following result: Resl. Inf. 12.59 7.75 5.84 4.77 4.08 3.59 3.22 2.94 2.70 2.51 2.35 N(data) 79 257 429 635 811 1010 1235 1384 1698 1555 1954 Chi-sq 0.69 0.63 0.60 0.67 0.61 0.88 1.05 1.02 0.80 0.55 0.42 79.4 34.1 30.3 32.2 31.8 26.6 21.1 14.6 8.3 3.9 2.4 %Complete 94.0 98.1 97.5 99.5 99.4 99.0 99.7 100.0 99.9 85.4 96.1 Multipl. 4.0 4.5 3.9 4.5 4.7 4.2 4.4 4.8 5.0 4.3 4.4 R(pim)% 2.27 1.72 2.29 2.05 2.02 2.62 3.51 4.84 7.90 14.43 22.78 Ranom% 6.49 3.68 5.19 4.29 4.27 6.35 9.50 12.97 20.90 33.58 52.21 0.73 0.80 1.08 0.85 0.95 1.03 1.00 0.91 0.85 0.78 0.70 CC(1/2) 5.1 41.7 68.8 38.1 42.7 49.9 49.9 25.5 24.9 13.3 -4.7 then I tried shelxd with different heavy atom sites number and resolution cut, the best CC I got is CC/CCweak: 24.75/7.69, and I can identify a triangle, (length: 6.5/6.5/5.0A), however, both shelxe and autosol didn't end up with a promising result. [image: image.png] It would be great if anyone can give me some suggestions. Thank you in advance! -- Tiantian