Xanthine oxidase and cytochrome c - superoxide assay

SB biswas.16 at osu.edu
Thu Jan 8 14:23:28 EST 2004

Jenny wrote:

> Hi, Happy New Year!
> I am trying to get a standard curve for superoxide by using adding
> xanthine oxidase to hypoxanthine, which produces superoxide which
> will reduce ferricytochrome c.  I am using a spec, at 550nm and so
> far nothing is happening... i was wondering if anyone has tried this,
> or knows if the enzyme needs special attention when being thawed and
> resuspended in buffer (i am using pH7.4 phosphate).
> looking forward to hearing from someone!!
> jenny mortimer

Hi Jenny

I hope you are not freeze-thawing the xanthine oxidase. The one we got
from Sigma is to be stored at 4 degrees C only and not to be frozen. I
have tried this and got a textbook response but I used xanthine instead
of hypoxanthine.


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