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[ccp4bb]: Filters for DLS measurements
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Dear collegues,
this question is not related to CCP4 programs but the problem may be
nevertheless interesting for the majority of CCP4 users:
Which filter size do you normally use to prepare protein solutions for
dynamic light scattering measurements? Is it really necessary to take 0.02
micrometer filters as recommended by ProteinSolutions and found in many
papers, or are 0.2 or 0.1 micrometer filters also reliable?
In our lab some people made good experiences with 0.2 micron filters. In one
case good DLS data (monodisperse solution) and excellent and reproducible
crystals afterwards were obtained. However after filtering the same protein
solution with 0.02 micron filters the protein was apparently away. At least
no DLS signal could be detected any more. Normally this observation itself
could be interpretated as an indication of aggregation, but the
crystallization results do not support this idea.
So is it generally legitimate to swap to 0.2 micron filters if 0.02 micron
filters catch away the protein? How are your experiences?
Any suggestions are wellcome!
Karsten
----------------------
Dr. Karsten Niefind
Institute of Biochemistry
University of Cologne
Zuelpicher Strasse 47
D-50674 Cologne
tel.: +49/221/470-6444 (Secretary: +49/221/470-6440)
fax: +49/221/470-5092
E-mail: Karsten.Niefind@uni-koeln.de
Internet: http://www.uni-koeln.de/math-nat-fak/biochemie/ds/ma/kni/inhalt_englisch.htm