[ccp4bb] stock solution of glutathione

[rashmi panigrahi]

Hi,
I wanted to use  glutathione for cocrystallizing with my protein at about
5mM concentration. What is the concentration of the stock solution to be
prepared for crystallization studies. Do I have to make the stock solution
of glutathione fresh each time or can I make the stock and store at
-20degrees? Should I prefer to make the stock solution at a particular pH
to prevent its oxidation??
suggestions awaited.......
-- 
rashmi