Eva Yes batch under oil will solve the problem. We regularly used to crystallize conditions with high levels of MPD under oil without difficulty.
I agree that the protein might be reducing the surface tension, but I've never heard of such a strong effect. Maybe the protein is unstable and "wants" to denature onto the surface of the plate. Is it possible that you have any low-molecular-weight organics in your protein sample? You could try the "UV-compatible" versions of crystallization plates because they're more hydrophobic than the regular PS ones. The polypropylene ones are even more hydrophobic, similar to siliconized glass. Salt precipitants will tend to reduce drop spreading, PEG to increase it. It's partly a matter of surface tensions, partly of the affinity of the ingredients for the plastic/glass. The air-liquid interface energy competes with the liquid-solid interface energy. Patrick On 7 November 2012 13:41, anna anna <marmottalb...@gmail.com> wrote: > Why don't you try batch under oil? > > 2012/11/7 Eva Bligt-Lindén <eva.bl...@abo.fi> > >> Dear ccp4 users, >> >> I have a problem in the crystallization of my target protein. Whenever I >> set up a vapour diffusion experiment, either hanging or sitting drops, the >> drops spread out. The surface tension is completely lost in 80-90% of the >> droplets. Have any one experienced something similar? What could be the >> reason for this strange behaviour? I have tried three different commercial >> screens with 96 condition each and there is no difference between the >> screens. There is no difference between manual or robotic setups either. >> The protein buffer is 40 mM Tris, 2 mM MgCl2 buffer, pH 7.4. The buffer >> controls are all ok. >> >> Kind regards, >> Eva >> >> ______________________________**______ >> >> Eva Bligt-Lindén (M.Sc.) >> PhD student >> Structural Bioinformatics Laboratory >> >> Department of Biosciences, >> Åbo Akademi University >> BioCity, Tykistökatu 6A >> FI-20520 Turku >> Finland >> > > -- patr...@douglas.co.uk Douglas Instruments Ltd. Douglas House, East Garston, Hungerford, Berkshire, RG17 7HD, UK Directors: Peter Baldock, Patrick Shaw Stewart http://www.douglas.co.uk Tel: 44 (0) 148-864-9090 US toll-free 1-877-225-2034 Regd. England 2177994, VAT Reg. GB 480 7371 36
