Our lab was in talks with NASA for awhile and came across several
hitches in the process including vibrational damage of the crystal
during reentry and the speedy freezing of crystals once they land,
neither of which is relevant if you are diffracting in space.
What is relevent however is the crystallization vessel. You want
to achieve nucleation after you have reached microgravity. The
current apparatus employed by the US is an expertly machined and
very expensive dialysis chamber with the precipitant solution
separated from the protein via agarose to slow the exchange. Your
crystallization conditions need to be tweaked quite a bit to get
this working and the chamber is not even vaguely conducive to
automation. The Russian space program uses something that is
essentially thin vacuum tubing with protein and precipitant plugs
and the ends sealed. This might work for automation assuming that
you can find a material that won't diffract.
I am assuming that if the diffractometer is on the space station,
the X-ray source will be an no stronger than a standard in-house
source. Cryoprotection might not even be necessary assuming that
you have decent crystals. Though the "getting decent crystals"
part is going to be difficult as most drug target proteins are
less than well-behaved.
The end product of my brief dance with microgravity
crystallization was that it was an inordinate amount of work for a
microscopic benefit. That might change if purely automated system
could be developed, but given the current technology it seems a
long way off.
That's my two cents for what it is worth.
Katherine Sippel
On Mon May 10 10:54:54 EDT 2010, Henry Bellamy <hbell...@lsu.edu>
wrote:
It is true that you can grow extraordinarily well ordered
crystals in microgravity and, at least in many cases, much
larger crystals. But, as a practical mater, the crystals need
to be cryocooled for data collection to reduce radiation damage.
Cryocooling increases the disorder (mosaic spread) to such an
extent as to obliterate the advantage of microgravity growth.
This applies even when comparing crystals of the same size.
For a reference see: Acta D59 2169-2182 (2003) Vahedi-Faridi
et al.
The large highly ordered crystals from microgravity might be of
great value for neutron work where cryocooling is not required
but that would be a small corner of a niche market.
HTH
Henry Bellamy
Associate Professor - Research
Center for Advanced Microstructures and Devices
Louisiana State University
6980 Jefferson Hwy.
Baton Rouge LA 70806
225-578-9342 (voice)
225-578-6954 (fax)
hbell...@lsu.edu
--
SIPPEL,KATHERINE H
Ph. D. candidate
McKenna Lab
Department of Biochemistry and Molecular Biology
College of Medicine
University of Florida
