When using oil on protein crystal mounts I suggest: 1. once the crystal is under oil, remove as much adhered solution from the crystal surface. 2. if there are any volatile components in your drop condition, presaturate the oil with that solvent. 3. consider using perfluoropolyether since it has a much lower viscosity than ParatoneN, has a very low vapor pressure (used in turbo molecular and diffusion pumps) and is immiscible with just about everything.
And remember that some membrane bound crystals will dissolve in oil. Kris Kris F. Tesh, Ph. D. Department of Biology and Biochemistry University of Houston ________________________________ From: Tommi Kajander <[email protected]> To: [email protected] Sent: Mon, February 6, 2012 1:04:13 AM Subject: Re: [ccp4bb] Freezing crystal if you use oil do direct dry Paratone-N, with paraffin oil is not as good. Li-salts should work also - i would almos imgaine you can freeze directly from so high (NH4)2SO4 conc. but perhaps not. little bit (10%) glycerol probably does it also.. Tommi On Feb 6, 2012, at 12:55 AM, Vineet Gaur wrote: Hi Theresa, >Once I had crystals in 3.5 M Amm. Sulfate. I used Paraffin oil and >Paraton-N-oil >(in 1:1 ratio). I also used 30% Xylatol. > > >Best, >Vineet > > >On Sun, Feb 5, 2012 at 5:49 PM, Theresa H. Hsu <[email protected]> wrote: > >Hi all >> >>Is there a list of conditions to be tried *first* for cryoprotectant? My >>crystals diffract at room temperature capillary but no in 30% PEG 400. >>Crystals >>are from 2 M ammonium sulfate. >> >>Thank you. >> >>Theresa >> >
