Hi there,

NADH powder is light yellow so it  naturally gives a light yellow colored solution from the start which intensity depends on concentration (color noticable in millimolar range). To avoid any trouble with NADH degrading, solution should always be freshly-made, pH lightly alkaline, kept at 4°C in the dark and solution devoid of any phosphate which promotes NADH degradation.

Beta-NADH can be stored desiccated; it needs to be protected from light. Solutions of Beta-NADH need to be freshly prepared as needed, and promptly used unless excessive care is taken. Reports document that powerful enzyme inhibitors are formed in frozen solutions; the inhibitors have the same absorbance at 340 nm as beta-NADH. During storage, a dimer of dinucleotide formed has been identified. Another compound formed from beta-NADH in storage is generated from beta-NAD in the presence of high concentration of phosphate ions and at alkaline pH.

Thank you! But I can't explain why it turned in yellow-ish color? Does that mean that had been oxidized because I  had stored in presence of lights for about one month or so!

Hi there,

NADH powder is light yellow so it  naturally gives a light yellow colored solution from the start which intensity depends on concentration (color noticable in millimolar range). To avoid any trouble with NADH degrading, solution should always be freshly-made, pH lightly alkaline, kept at 4°C in the dark and solution devoid of any phosphate which promotes NADH degradation.

Does anybody knows which is the yellow compound ? was it isolated ? Is there any reference on this ?

It's very weird that the NADPH I got from different manufacture has different colors. The first vial I got from Sigma has a yellow color once I dissolve it in HPLC water, but the second vial I got from Fisher is colorless in water. Both brand new and dissolved in the same concentration. Does anyone know why is it? BTW, they suggest different storage method, Sigma said store the powder at 2-8°C, but Fisher said store the powder at -20°C.

NADPH should be colorless. If it is yellow, it is probably due to degradation or impurities. They may not be enough to cause a problem with your experiment, but if you have colorless NADPH, you should use that. I would store the powder at -20oC. I would not store the solution. Just make up enough solution for one day's work and keep it on ice.

As mentioned by other it’s colorless and discoloration indicates instability and should not be used. We use this for drug metabolism study and always prepare it fresh. As for the powder form, we store it in -20 C.