Perhaps of interest here could be Santovac 5. It's an oil that does not
mix with anything, not water, not mineral oil, not alkanes, not
perfluoropolyether, not silicone oil, not paratone. Nothing but
acetone. It is a a polyphenyl ether that was originally developed as a
diffusion pump oil since it has an incredibly low vapor pressure (4e-10
torr). This is equivalent to saying that the molecules REALLY don't
like leaving their oil phase, and therefore won't go into your protein.
It's also non-toxic. Seems to me that as "non-penetrating"
cryoprotectants go these are all desirable properties. You can get it
from spi.com.
-James Holton
MAD Scientist
On 12/4/2012 6:42 AM, Jens Kaiser wrote:
> Ulrike,
> I usually suggest it as the second try (the first try is mother liquor
> alone), as it does not involve mixing any new buffer concoctions. I do
> not have hard data, but I'd estimate it worked in about 50% of cases; it
> seemed not to matter if you try it on a soluble or membrane protein
> crystal. In my hands it performs better than mineral oil, silicon oil or
> paratone. Problematic cases are crystals in heavy precipitate, which has
> to be removed prior to transfer into the oil, otherwise it sticks around
> the crystal and you can't get the crystal "dry".
>
> hth,
>
> Jens
>
> On Mon, 2012-12-03 at 13:07 +0000, Ulrike Demmer wrote:
>> Dear crystallographers,
>>
>> does anyone have experience using Perfluoropolyether (Hampton Research) as cryoprotectant for membrane proteins ?
>>
>> Cheers,
>>
>> Ulrike
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