I have to do an enzyme kinetic assay using NADPH as a substrate (10 mM) and in one shot I cannot finish my kinetic assay with all the fractions collected at each step of the purification. By that time the prepared NADP could be oxidized!
Comparing all assays that belong together in a single experiment is always the best you can do. On the other hand, I never had problems with storing stock solutions of NAD(P)H at minus 20 degrees. If, after many thaw/freeze cycles oxidation becomes a problem, you will see this immediately in the photometer. Courage!
Better to complete at one shot, Collect all ur fractions or samples and store them at -80C.
if u keep NADPH at -80 for further use the readings may fluctuate and it is not advisable, as i hav done this assay.
Comparing all assays that belong together in a single experiment is always the best you can do. On the other hand, I never had problems with storing stock solutions of NAD(P)H at minus 20 degrees. If, after many thaw/freeze cycles oxidation becomes a problem, you will see this immediately in the photometer. Courage!
Storing at minus 20 or minus 80 degrees for a short period is OK. However, after several thawing/freezing cycles it deteroriates. The key is, target to use all the solution once opened/prepared!!
prepare stock solution, make small aliquots so that you can use one aliquot at a time. This stock is stable at -20 degrees for 8 days at least.
I used NADH stock kept in -80, make sure you keep it in the proper pH, as NADH is bets kept in alkali conditions and rapidly degrades in acid.
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