Chris Isopropanol is said a very good precipitant but it's unpopular because it's so difficult to harvest crystals
However there's a very convenient way to grow and harvest crystals in isopropanol using Vapor Batch plates. Basically you set up microbatch-under-oil drops containing all the ingredients except for the isopropanol, and cover with Al's Oils (silicone mixed with paraffin oil). Then you put e.g. in your case 25% isopropanol in the reservoir around the outside of the Vapor Batch plate. Over a few hours the isopropanol will diffuse through the Al's Oils into the drops. The great advantage is that the oil also becomes saturated with isopropanol (they are only partially miscible in fact) so that the oil acts as a barrier when you're harvesting crystals. You can usually convert vapor diffusion conditions to microbatch in a single 24-well experiment where you vary protein against precipitant. You don't need to remove the oil to collect data. This is all described in Lesley Haire's winning entry to a competition we organized a few years ago: http://www.douglas.co.uk/winner1.htm See also Mortuza et al. High-resolution structure of a retroviral capsid hexameric amino-terminal domain. Nature 431 (2004), pp 481-485. The Vapor Batch plate can be seen at http://www.douglas.co.uk/vb.htm If you or anyone on the b.b. would like to try some samples of Vapor Batch plates just let me know Best wishes Patrick On Fri, Apr 9, 2010 at 9:53 AM, Chris Meier < crystallogra...@christophmeier.com> wrote: > Dear all, > > I have a protein which crystallizes in 25% isopropanol, at pH4.5. > > Does anyone have experience freezing crystals grown in such a condition? > What cryoprotectants should I try? > Can isopropanol itself act as a cryoprotectant? > Any suggestions on how to deal with isopropanol evaporation during > mounting? > > Many thanks and best wishes, > Chris > > > -- patr...@douglas.co.uk Douglas Instruments Ltd. DouglasHouse, EastGarston, Hungerford, Berkshire, RG177HD, 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
