Dr. Artem Evdokimov eudokima at mail.ncifcrf.gov
Mon Apr 30 07:14:14 EST 2001


Glad to help.

Actually filtering is necessary if you are working with any kind of FPLC
or HPLC system, or using expensive fine-grain columns (such as the
'monoX' series, hydroxyapathite, 5u C-X and CN-X series, superdex etc.). 
Our AKTA's really appreciate filtered solutions - in fact everything we
put on them is filtered, including cell lysates. It helps a lot - you
won't believe what kind of junk one finds in commercial salts and
chemicals, even in the 'super-duper clean' ones (most common are fibers
from some kind of sacking, it would appear). Autoclaving does not
eliminate all particulate matter, so if you are working with any kind of
precision machinery, expensive columns etc. then 0.22 u filter is your
best friend.

We are mostly dealing with proteins being prepared for crystallographic
studies so as you can imagine, the amounts of liquids that we put
through the systems are quite large, but even for small samples
sometimes just one piece of fiber is enough to crack your column or
increase the backpressure or get stuck in your pumps and
cross-contaminate your sample.



Michael Witty wrote:
> Dear Artem, Patrick, Isabelle and Richard,
>                                          thanks for your replies.  I have
> tried IMAC with imidazole filtered and non-filtered but my instinct (being
> a molecular biologist) is to autoclave anything I can in a compulsive and
> probably self destructive way.  Bottom line: even filtering was not
> necessary.  I still feel dirty.  Mike.

|Dr. Artem Evdokimov   Protein Engineering |
| NCI-Frederick        Tel. (301)846-5401  |
|              FAX (301)846-7148           |
|        eudokima at mail.ncifcrf.gov         |
|      http://www.ncifcrf.gov/plague       |

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