Dear fellow scientists,
I stumbled upon literature stating that the commonly used phosphotyrosyl phosphatase inhibitor sodium orthovanadate is potently chelated by EDTA. This may be a problem when phosphotyrosyl residues are to be conserved during and after cell lysis as cell lysis buffer usually contain EDTA.
Do you have any suggestions as to how to circumvent this problem? I read that EGTA may be an alternative because affinity to vanadate is less strong. Instead of vanadate pervanadate can be used because it inhibits tyrosine phosphatases irreversibly. But I don't see any buffer recipes substituting vanadate with pervanadate.
Any suggestions how to sort this out?
Best
Thomas
Hi Thomas,
Just for my understanding: orthovanadate is an anion, right? And EDTA is too, as it is frequently used to chelate multivalent cations. How is it (physically) possible that these two negatively charged entities interact according to the literature you're referring to?
Regards.
Hi Eef,
Good point. I will just provide you with the literature as I have not yet studied them in great detail.
"More important, though, is the interaction of vanadate with EDTA. This interaction has been well documented" from doi: 10.1074/jbc.272.2.843 January 10, 1997
Have a look at references 32-35 of this paper.
Best
Thomas
I had the same thought as Eef Dirksen when I read your question, but then I remembered that EDTA is also a diamine and it seemed more plausible that it could interact with anions. I saw it written that the pKas of the nitrogen atoms are 6.1 and 10.4, so at one of them is protonated at typical pH of biological buffers.
I did a little research and found this. You may be interested.
Debbie C. Crans (1994) Aqueous Chemistry of Labile
Oxovanadates: Relevance to Biological Studies, Comments on Inorganic
Chemistry: A Journal of Critical Discussion of the Current Literature, 16:1-2,
1-33, DOI: 10.1080/02603599408035850
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