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Hi everyone, We got crystals that grew in ~3.2M ammonium sulphate and some tris-buffer at 18dgC. Unfortunately the crystals take a while to grow (~4-5 weeks) and so far we only have 4-5 xtals. I tried to freeze the crystals, but as soon as I broke though the skin of the drop the ammonium sulphate started to crystallise. I got the crystals out, froze them using sort of an artifical mother liquor with sodium malonate as cryo and tested the diffraction. The freezing seems to be OK and it is definitely a protein crystal. The crystal suffered when the ammonium sulphate in the drop started to crystallise, but didn't seem to deteriorate anymore in the cryo. Well the corners had already more or less disappeared by the time I got them out of the drop... Since we only have a few xtals at the moment and I can't try out a lot of things, I was wondering if anyone has experienced and solved a similar problem? My freezing attempt so far was in an airconditioned room with 18dgC. I thought about higher humidity and temperature in the room, and/or adding the cryo directly to the drop.... Any ideas are very much appreciated! Sabine ------------------------------------------ Dr. Sabine Schneider Ludwig-Maximilians-University Department of Chemistry and Pharmacy Butenandtstrasse 5-13, Building F 81377 Munich Germany Phone: +49 (0)89 2180 77846 Fax: +49 (0)89 2180 77756 http://www.carellgroup.de/