Dear CCP4bb,
1) Check the bottom of the tube from which the protein was taken. Round
objects could be sephadex beads.
2) Touch the object with a cat wisker. Does it break up easily?
Yes: probably protein crystals. If it is an oil instead of a solid object
you have
your answer.
3) If these objects break up easily can you use them as seeds?
If so, it is well worth optimizing!!
Birefringence is also useful, but you need to know your salts. Some are
difficult
to distinguish from small (less than 60 aa) proteins that can also be
strongly birefringent.
Birefringence is useful in particular if you check how fast the color
changes as you rotate the
cross-polarizer. Portein crystals tend not to change color as fast as salt
crystals do. Sephadex
beads are not birefringent.
Enrico.
On Thu, 07 Jun 2012 00:10:47 +0200, Jacob Keller
<[email protected]> wrote:
Birefringence?
JPK
On Wed, Jun 6, 2012 at 4:52 PM, Harman, Christine <
[email protected]> wrote:
Hi All,
I have these very weird drops that I found from screening (please find
pictures attached). I am not sure if they are worth optimizing. I am
very
interesting to know your opinions of what you think of these drops
could be
(are these what you call "spherulites"?). If you think these conditions
are worth optimizing, I welcome any ideas on how to optimize. I have
done
some optimization and still get the same result which is many of these
weird things growing throughout the drop and with no sharp edges, and
sometimes a skin forms after 2weeks (with the sodium malonate conditions
only). I have also opened the drop and poked around to see if it is
phase
separation and this things are definitely solid and slightly-very
mushy. I
haven't had a chance to check for diffraction, but will be very soon.
Both of these drops contain the same protein preparation of a
Fab/peptide
complex @ ~5mg/mL in buffer containing 0.1M Sodium Acetate pH 5, 150mM
NaCl. I appreciate any advice, thoughts or comments that you could
provide.
Peace,
Christine
--
Enrico A. Stura D.Phil. (Oxon) , Tel: 33 (0)1 69 08 4302 Office
Room 19, Bat.152, Tel: 33 (0)1 69 08 9449 Lab
LTMB, SIMOPRO, IBiTec-S, CE Saclay, 91191 Gif-sur-Yvette, FRANCE
http://www-dsv.cea.fr/en/institutes/institute-of-biology-and-technology-saclay-ibitec-s/unites-de-recherche/department-of-molecular-engineering-of-proteins-simopro/molecular-toxinology-and-biotechnology-laboratory-ltmb/crystallogenesis-e.-stura
http://www.chem.gla.ac.uk/protein/mirror/stura/index2.html
e-mail: [email protected] Fax: 33 (0)1 69 08 90 71
