OK. Despite the FOCUS article which suggests that Proteinase K is very
stable in solution, my stocks, which are in 10 mMTris-Cl (8.0), 1 mM CaCl,
50% glycerol seems to loose activity after several months in the freezer.
Stocks made by other hands are dead already after just two months or so.
My indication that they are inactive is that I generally clean up
analytical in vitro transcriptions (E. coli pol) by merely Proteinase K
and precipitation rather than organic extraction. After a few months,
RNA samples fail to migrate out of the wells, presumably due to the
presence of added RNA binding proteins.
I'll repost after making a new Protienase K stock. Anyone else see this ?
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