Aqueous soluble tetrazolium/formazan MTS as an indicator of NADH- and NADPH-dependent dehydrogenase activity.Nicotinamide adenine dinucleotide (NAD+ in its oxidized form) and its close analog nicotinamide adenine dinucleotide phosphate (NADP+) are composed of two nucleotides joined through their phosphate groups by a phosphoric acid anhydride bond. Ethanol is right solution because one of the carbon atoms has undergone the loss of hydrogen and has been oxidized from an alcohol to an aldehyde.

Hi, Bin, why do you plan to use DMSO??both compounds well-dislove in water. So you do not need to use DMSO. Plesae, look here as well:  http://www.ncbi.nlm.nih.gov/pubmed/8777059

These and other nucleotides will not dissolve well in DMSO because they are very polar and charged. They can be dissolved to high concentrations in aqueous buffers. NADH will dissolve to at least 100 mM in water with neutralization, and NADPH even higher. Bear in mind that these reduced nucleotides will oxidize once dissolved, so it is best to make a fresh solution each day.

Thanks, Ravi, Taras, Adam.   Yes, I know NADPH and NADH can be well dissolved in H2O and maybe even better stability in sodium hydroxide solution. The reason why I am asking is I am using an assay kit to quantify them, and the protocol suggest to dissolve the standard NADPH and NADH in DMSO. I am confusing about this because I have ever tried to dissolved NADPH tetra Na salt into DMSO to achieve the same concentration as that in the protocol (1mM), and found it cannot dissolved quite well (precipitates can still be seen). So, I am doubting whether those commercial assay kits are concise enough. 

We only used aqueous buffers in the MTS/NADPH/NADH experiments. Terry Owen specifically designed the MTS compounds to be water-soluble. I don't recall any data using DMSO, but as a chemist he may have tested the range of solubilities...unfortunately, he is gone.

Thanks, David. I guess the assay kit supplier is aiming to extend the expiry date of these solutions for storage, but few data can be found online about the solubility and stability of NADPH and NADH in DMSO. I am contacting the supplier to see if they can share any information.

And sorry to hear that. It is really a pity for everyone when a good researcher leaves us.

It might be possible to increase the solubiity of the nucleotides in DMSO by starting with the free acids rather than the salts. Another trick is to use a large organic counterion such as triethylammonium instead of the usual sodium. I was able to make a solution of EDTA in DMSO this way, starting with the free acid.

Thanks, Adam. I will try further to see if any progress can be made.

To anyone who want to know the solubility of NAD(P)H in DMSO, I just got a confirm from the assay kit supplier. Actually, to dissolve NADPH in DMSO, they firstly dissolve its tetra Na salt in akaline solution and then lyophilized; that makes the lyophilized powder soluble in DMSO. Directly dissolving NADPH tetra salt into DMSO doesn't work.

FYI.

I don't understand why the NADPH is more stable in NaOH.  The NaOH is not going to transform NADPH into NADP+?