frozen crystal recovery devices

Satish Nair satish at a.chem.upenn.edu
Thu Oct 24 15:54:23 EST 1996


In article <54o960$f1c at neonlights.uoregon.edu> pbr at uoxray.uoregon.edu writes:
>
>Hi everybody,
>
>I am interested in any information about devices
>for recovering frozen protein crystals.  This is a problem
>for me, because I would like to characterize some frozen
>crystals and then store them in N2 for later data collection.
>(i.e. a synchrontron trip)
>I would like to be able to remove my crystals, which are mounted in
>a loop attached to a magnetic base, and store them in cryovials
>(i.e. Hampton). However I am working on a Raxis with a vertical 
>spindle which does not allow for the easy removal of frozen crystals. 
>I am interested in a device that will allow the mounted crystal to 
>be rotated such that it will be in a vertical position for recovery
>into a cryovial filled with liquid N2.
>I have read the short communication by Mancia in J. Appl.Cryst (1995) 
>which briefly describes such a device, but was wondering if 
>anyone knew of a more complete description of such a device. Mancia does 
>not mention anything about problems related to his device freezing.
>We currently have a heated jacket over our goniometer to keep it from
>freezing and locking up, so I know this can be a problem.
>

A couple of ways to do this:

1. I think either Supper or Hampton sell an attachment with an arc
 which allows for vertical-horizontal movement of frozen crystals.
 Once the crystals are arced into a horizontal position, one can
 subject them into propane filled cryovials for storage.  You have
 to be judicious in your choice of pin size to assure that the
 crystal remains in the N2 stream during the movement.

2. We use a forcep-like device which has a solid, stainless-steel
 encasing attached at the end.  The encasing also has a groove which
 matches the dimensions of a mounting pin/loop and encloses frozen
 crystals when the forceps are shut.  The encasing is cooled to
 the desired temp in liquid N2 and then is used to enclose and
 recover frozen crystals.  A little trickier to work with but 
 extremely reliable.

satish nair







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