proteinase K solutions

[Howard T. Petrie]

We use proteinase K for DNA/RNA purification, etc.  We make it up at
20mg/ml in water and store it frozen, as all of the prominent methods
texts recommend.  In the past (we have historically purchased it from
B-M), there has always been a precipitate in this solution.  We recently
purchased some from Stratagene, and there is no precipitate at the same
concentration.  What are other peoples' experiences with proteinase K in
solution?  Are precipitates common?  I would also be interested in hearing
specifically from people who use Stratagene's proteinase K.  If you don't
want to respond in public, my e-mail address is
h-petrie at pop.ski.mskcc.org.  Thanks.