micrococcal nuclease

Anton Tutter atutter at aim.salk.edu
Sat Nov 20 20:11:12 EST 1999


in article 38302367.74CCB00D at uni-konstanz.de, Frank O. Fackelmayer at
Frank.Fackelmayer at uni-konstanz.de wrote on 11/15/99 7:14a:

> Hi all,
> We use micrococcal nuclease to solubilize chromatin proteins from nuclei
> of human cells. A problem we now encountered is that the nuclease of at
> least two major suppliers are contaminated with protease that degrade
> our proteins on the fly. Does anyone out there know of a good source of
> MNase that has NO protease contamination? Unfortunately, checking for
> protease activity is not part of the quality control procedures of the
> two major suppliers we have problems with (Boehringer Mannheim,
> Pharmacia).
> Any suggestions?
> 
> Thanks in advance,
> Frank
>
 
we use sigma MNase for our chromatin digests.  Beware, different
manufacturers use different definitions for units of activity.  we've
titrated the sigma MNase and we get complete digestion down to
mononucleosomes with 0.56 Units/microgram DNA (calc. free DNA) in 25 minutes
at room temp.  we are adding it to in vitro chromatin extracts, not intact
nuclei.

hope this helps...

_______________________________________
Antonin Tutter
Salk Institute for Biological Studies
RBIO-J
10010 N. Torrey Pines Rd.
La Jolla, CA  92037
email:  tutter at salk.edu
web:  http://www-biology.ucsd.edu/~atutter/






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