CNBR cleavage

Deb McMillen (mcmillen@morel.uoregon.edu)
Thu, 04 Mar 1999 10:08:53 -0800

I think I got this idea from the bulletin board several years ago, but I
keep a stock of CNBr (not a big stock, just 1 ml in a 4 ml screw cap
vial with a teflon-lined cap and then this vial is held upright in a
larger screw cap plastic container in the freezer) in neat acetonitrile
so that it is easily added to samples for reaction--I do most of my CNBr
cleavages in 0.1M HCl with 30% acetonitrile. I haven't had to weigh out
CNBr for a long time and use only what I need for each small cleavage
reaction. Let the vial come totally to room temperature before opening
to minimize the amount of water that the acetonitrile takes up. I've
not bothered to top with argon when I store and the solution seems to
give good results after even two years (I always run a control protein
alongside my unknown so I'll know the day that the CNBr stops working!).

This technique may not work for those using mass spec analysis of the
fragments (I do not know about any by-products I might have from long
term storage of the CNBr in Accn) but it has worked fine for mapping
(using HPLC or PAGE) and N-terminal protein sequencing on my old ABI
470.

Deb McMillen
Institute of Molecular Biology
University of Oregon
Eugene OR 97403