Re: Good Pepsin source

Katheryn Resing (Katheryn.Resing@Colorado.EDU)
Tue, 2 Feb 1999 17:58:13 +0000

We use sigma pepsin for deuterium exchange--pepsin isn't usually
contaminated with anything serious, but then who would know, since pepsin
doesn't seem to have a cleavage specificity that I could figure out.
Enzyme only controls showed only a couple of trace components, even at very
high protein concentrations. We made it up in water, spun out the
insoluble stuff, made 100 aliquots and froze them at -80 and thawed a fresh
one each day. This seemed to give very reproducible cleavage patterns,
even a year later. There is something in the pepsin that will give
precipitates when mixed with some buffers, at the high concentrations that
we use for deuterium exchange.

Katheryn Resing