How to deplete Oxygen from enzyme assay?
david.moss at ifia.fzk.de
Fri Sep 26 14:40:44 EST 1997
William P. Tschantz <tschantz at galactose.mc.duke.edu> wrote
> I am looking for an easy way to deplete a system of oxygen. I suspect
> that the enzyme i am working on uses molecular oxygen in its mechanism
> would like to test it. I have tried degassing my samples and reaction
> vial with nitrogen, but have gotten messy results. Enzyme linked assays
> would be the easiest i think.
I did some experiments on ways to deplete reaxtion mixtures of oxygen
during my doctorate. I found degassing with nitrogen leaves large, variable
residual concentrations. A few grains of dithionite is the most efficient
but the strong reducing conditions may damage your enzyme. More mild
but nearly as good is glucose oxidase + glucose, as long as you don't mind
having a second enzyme around. You could also try anthraquinone sulfonate:
you can photoreduce it with light from a slide projector in the presence of
HEPES or similar buffers, then it autooxidizes, consuming all the oxygen
The reaction is autocatalytic (quinone-mediated), so you get down to very
low oxygen tensions very fast. As soon as you switch off the lamp, you
no longer have a damagingly strong reducing agent. I ended up using
anthraquinone sulfonate and glucose oxidase together, with a trace of
to dispose of any hydrogen peroxide formed.
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