Hi everyone,
I am trying to make 1mM sodium orthovanadate (Na3VO4) for the live-cell imaging experiment. According to the protocol, pH should be adjust to 10, however, can I reduce it to pH7.4 because I want to let it same as pH of imaging buffer . I tried to adjust it into 7.4 and found most of Na3VO4 was precipitated and the color of the solution became dark-orange....
Could anyone who had the same problem please give me a feedback on this issue? Thank you!
Dear Chen,
I strongly advise you to dissolve sodium orthovanadate in a pH 8-buffered solution. Tris (hydroxymethyl amino methane) will do well since its PKa is around 8.0, therefore having a good buffering capacity at this pH. I would suggest preparing a 10-100 times vanadate stock solution in 20 mM Tris-HCl pH 8.0. Please leave it standing overnight at room temperature (protected from light) for complete dissolution. You can make up to the final volume on the following day after vanadate has been dissolved. Never try to dissolve vanadate by heating since you will end up with a mixture of different vanadium oxidation components. Please find attached a paper in the hope that it may help you. Good luck. Pedro.
Pedro J Romero
Dear Pedro,
Thanks! I look up the attached paper you sent to me. May I ask you some questions? Because our lab use Sodium orthovanadate( Na3VO4) and I am quite confused about NaVO3 mentioned in that paper. What’s the difference between Na3VO4 and NaVO3? Could I follow the same protocol for Na3VO4 preparation according to the paper? Besides, if I leave it standing overnight at room temperature and will color change from yellow to translucent? I am looking forward you explanation. Thanks.
Chen
Sodium orthovanadate and sodium metavanadate are different chemical compounds, having different effects on biological systems (please see : Vanadium and its inorganic compounds https://onlinelibrary.wiley.com/doi/pdf/10.1002/3527600418.mb744062e0025). As far as I know, orthovanadate (VO4 -3) and metavanadate (V03 -1) anions (+5 V oxidation state) are equally potent in inhibiting ATPases and phosphatases. I assume that you will be using vanadate for this type of inhibition. I guess that you could follow the same protocol for Na3VO4 preparation according to the paper with similar results. It is very important to keep an alkaline pH (around 8) since at lower pH values V ions are oxidized by H ions, thus forming decavanadate complexes. Likewise, the colour of the solution will change from colourless into yellowish-orange. Please, see attached Chemistry of Vanadium - Chemistry LibreTexts .
Also see Dmitry Kharitonov answer added in the following Research Gate post: https://www.researchgate.net/post/Why_is_that_my_sodium_orthovanadate_Na3VO4_aqueous_solution_looks_a_little_bit_green.
Best of luck. Pedro.
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