Dr. Artem Evdokimov
eudokima at mail.ncifcrf.gov
Wed Mar 28 12:01:09 EST 2001
My 2 cents:
I have collected 2.4 A data from 0.05x0.03x0.03 mm crystals at
Brookhaven, line X9B. This was not a small protein, by the way, 47 kDa
in unit cell.
Exposure time was 5 minutes per degree, which is very long for
synchrotron. At Argonne, I could have gotten away with much less
exposure and probably higher resolution. Plus, they have a microcrystal
beamline with special optics for accurate centering and such.
I hesitate to call crysals 'too large' however it is certainly true that
very large crystals are very difficult to freeze. In general anything
above 0.5 is difficult. I am currently growing 2 mm protein crystals for
neutron experiments and I have yet to figure out how to freeze them.
Practically, if I were you I'd just shoot your crystals and see what
happens. Make sure that you are as close to the center of the beam as
possible - for very small crystals it makes a lot of difference.
Michael Witty wrote:
> Dear All,
> I am starting on some practical crystallization and have obtained
> some protein crystals which people have called "small". They are about
> 30 micrometers. What do you all think the words "big" and "small" mean
> regarding protein crystals. Or is that unimportant, and do we have to put
> the crystal into an x-ray beam to find out if it is a "good" protein?
> Regards, Mike.
|Dr. Artem Evdokimov Protein Engineering |
| NCI-Frederick Tel. (301)846-5401 |
| FAX (301)846-7148 |
| eudokima at mail.ncifcrf.gov |
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