half life of common protease inhibitors

Dr Engelbert Buxbaum engelbert_buxbaum at hotmail.com
Tue Aug 2 03:09:51 EST 2005

egf_repeats wrote:

> Hi, there,
> Can anybody point me to a place talking about the half-life of common
> protease inhibitors? I know PMSF is kind of short, ~30min in aqueous
> solutions. How about others?
> I used Roche's Complete tablet on my lysate at 4C and found after
> several hours that my protein was almost completely degraded.

I am no particular friend of such premixes, even though they are
convenient. It is much better (and in the long run cheaper) to identify
the inhibitors that actually protect in your particular case. I once
found that to protect Mdr1 from proteolytic breakdown during its
isolation the presence of aminocaproic acid (5 mM) is required - you
won't find that in many common mixes!

Btw, the short half-life of PMSF is not really a problem, since it
inactivates, rather than inhibits, Ser-proteases. So you need that only
during the initial lysing procedure. 

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