1
$\begingroup$

According to the MSDS for NADPH Tetrasodium Salt, it says to store it in a place away from heat and light. Does this include UV light or just visible light? I was told that a pure NADPH stock solution (with pH 7 phosphate buffer as solvent) could be re-used after absorbing UV light at 340 nm, but based on the MSDS it seems that shouldn't be the case. So my question is: could I reuse a sample of pure NADPH stock solution that was exposed to UV for my enzyme activity assay?

datasheets.scbt.com/sc-202725.pdf

https://www.interprise.com.br/produtos/download/90289.pdf

$\endgroup$

1 Answer 1

1
$\begingroup$

NADPH isn't destroyed by absorbing 340 nm light; if it were, then spectrophotometry wouldn't be a good technique to monitor its concentration. The primary stability concern with NADPH and NADH is acid-catalyzed decomposition. A great 1986 article summarizing this phenomenon is available here.

Some highlights from the article:

  • At 30 °C, the pseudo-first order rate constant for NADPH degradation in aqueous solution goes from 0.5 min$^{-1}$ at pH ~3 to $10^{-5}$ min$^{-1}$ at pH 10. At pH 7 the rate constant is $10^{-3}$ min$^{-1}$.

  • The rate is elevated slightly by higher concentrations of phosphate buffer, about 10x higher for 1 molar (!) phosphate vs. extrapolation to infinite-dilution phosphate.

A secondary pathway for NAD(P)H decomposition is oxidation by atmospheric air, but it is usually pretty minor compared to acid degradation.

So I don't think there will be a big problem with light destroying your NADPH. You might be able to re-use it, but it depends how long you let it sit in solution, and at what temperature.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.