Have you tried crystallising in microbatch format, i.e. under oil? I've had success with this method for exactly the problem you describe.
Regards. Antony --- sent from my mobile account --- > On 25 Feb 2015, at 08:39, Ulrike Demmer <ulrike.dem...@biophys.mpg.de> wrote: > > Dear crystallographers, > > I am trying to crystallize a soluble protein which tends to form aggregates. > The crystallization condition is 20% PEG 3350 + 0,2 M Na-Formate. During the > crstallization process a thick skin is formed on top of the sitting-drops. As > well the crystals are buried in precipitate. Before I start harvesting I try > to remove the skin but still it is hardly possible to get any crystals out of > these drops. > > Any suggestions how to avoid the formation of skin on crystallization drops ? > > Cheers, > > Ulrike
