Hi,
Some anecdotes here for your reference:
One paper I read says that the authors were having trouble reproducing a
crystal from an initial screen. After some debugging, they realized that it
was because that they used a same pipette tip when making screens. Adding a
little solution from the condition prior to the "hit" condition solved the
mystery.
Another paper I read said that they failed reproducing crystals until
realizing that the only success they had was that they forgot to add well
solution to the hanging drop(a very small protein domain though).
Of course there comes the famous example that the pioneer crystallographer
used a metal container to transfer meat from the butcher's for making his
protein. Then it turned out that the magic bullet for his success in
crystallization was the galvanized Zinc(or nickel?).
I guess there must be tons of such stories if we read through Acta D. :)
PEG is known to decompose in solution, I think something like lactate might
be generated. If your solution is strongly buffered by hepes (100mM at pH7.5
for example), the pH may not changed much even if you have a few mM of
lactate.
--------------------------------------------------
From: "Jun Yong Ha" <j...@princeton.edu>
Sent: Tuesday, April 12, 2011 7:56 AM
To: <CCP4BB@JISCMAIL.AC.UK>
Subject: [ccp4bb] Reproducing crystals.
Hi all,
Recently, I produced crystals with MBClass1-64 which contains PEG4000,
HEPES-Na and NaCl. But, I struggled to reproduce crystals. I tried to set
up tray with different batch of solution. I got the crystals only from
2008 solution, but not from fresh ones. I asked technical service of
Qiagen, but they did not have any stock.
pH between fresh and old solution is the same. I could reproduce crystals
with this old solution 100% when setting up.
Do you have any experience like this? Is PEG4000 degraded or oxidized?
Please help me.
Thanks in advance.
