SOD assay questions

[amlee3 from ncsu.edu]

Hi,

I was wondering if anyone knows of a good way to prepare xanthine oxidase
(bought Xanthine Oxidase from bovine milk, 25Units, Sigma Aldrich Cat. no.
X4500) for an SOD assay using the reduction of Cytochrome C method? (
McCord & Fridovich [(1969) J. Biol. Chem. 244, 6049-6055)  I'd like to
maximize the activity of xanthine oxidase and its longevity.  Several
suggestions from other labs said i needed to make it fresh each time, but
that seems like a waste, others suggest resuspension in a wing buffer
(50mM Pot phosphate, 0.1mM EDTA pH7.8) then dialyze it overnight.  Any
ideas?  A detailed protocol would be really helpful.  Thanks so much.

Alice