[ccp4bb]: microsource responses

["David J. Schuller" <djs63@cornell.edu>]

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a few days ago i asked for feedback from folk who have used Microsource 
generators for macromolecular crystallography.  I was surprised to hear 
from only one person who has worked with a Microsource (below).  i also 
received inquiries from several others who are currently shopping.

cheers,
 
=======================================================================
"Now that I'm a cranky, constipated old man I can afford to say that
 the younger generation of scientists makes me sick to my stomach."
                                                  - C.M. Kornbluth
=======================================================================
                        David J. Schuller
                        modern man in a post-modern world
                        MacCHESS, Cornell University
                        djs63@cornell.edu

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Bart Hazes says:
>From bhazes@ualberta.ca Mon Jan 28 16:19:59 2002

I would feel happier to deal with MSC than Bede and if they have a
microsource/Osmic combination than that may be the better choice (should
capture a wider cone of X-rays and give better monochromaticity).

As for performance, don't expect to get the same as a RA/Osmic mirrors setup,
but from your message it appeared you didn't.

Bart

PS why would anyone still buy a Yale mirror set?


>From bhazes@ualberta.ca Mon Jan 28 15:27:44 2002
You have the right motivation for buying one. I think the Bede could do very
well in a setup where you want to characterise your crystals, see if an
inhibitor has bound or not, freeze them for synchrotron trips, that kind of
thing. Then go to the synchrotron and collect your actual data set used for
refinement and maps. I think the Bede will be good enough for all of that and
the small space, ease of use should make it a worthwhile trade-off.

I used a Bede prototype while in Cambridge 2-3 years ago. It used the
cylindrical mirrors, no Osmic coatings. Monochromaticity isn't as good as with
the Osmic mirrors but that's not critical for your intended use. I also
noticed that my spots had a dimple in the middle, due to the cylindrical
mirror. I have to say that these were crystals with very low mosaicity and
extreme diffraction (.8Angstrom at synchrotron). For more typical crystals,
the mosaicity will probably fill in at least some of the dimple. The Bede may
have been improved further, they were thinking about Osmic mirrors at the
time, but even the original could be the right choice in the right
circumstances.