Hello Ulrike, In addition to other answers, one of the more esoteric (but surprisingly effective) ways to destroy the protein 'skin' on drops is to add a tiny bit of Trypsin solution. Crystals generally tend not to be affected, but (at least in my experience) the protein skin dissolves within a couple of hours or less. In at least one case, this was the only way to get rid of skin, which otherwise tugged on crystals and resulted in considerably worse diffraction.
Good luck, Artem P.S. needless to say, if your skin is made of something else then trypsinolysis won't work :) - Cosmic Cats approve of this message On Wed, Feb 25, 2015 at 2:34 AM, Ulrike Demmer <[email protected] > 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 >
