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Artem, > 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. > Will you go a bit further and say what exactly you mean by "a tiny bit of Trypsin solution"? :-) What is the composition of your successful trypsin solution? In what volume do you add it? Do you add it right on top of a sitting or hanging drop? Was your situation one in which the skin and crystals were fused? Was there a rationale for why you used trypsin as opposed to other peptidases (I imagine it's what you had on hand ...)? Emily. > 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 < > [log in to unmask]> 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 >> > >