I have to calculate the concentration of free divalent metal ion that is available in a enzyme reaction based on the log K value of particular metal-ATP complex.
Because the reaction also contains ATP, some amount of the divalent ion is sequestered by this molecule and remaining free metal is available to activate the enzyme.
If log K (@25C temperature and 0.1 ionic strength) values for the divalent metal and ATP are provided, then how to calculate Kd values?
Please give your suggestions...
It's more complicated than you might think because there are multiple equilibria for ATP that depend on pH, ionic strength, and temperature. Fortunately, there are papers and on-line calculators to help with this.
http://pubs.acs.org/doi/abs/10.1021/bi00310a025?journalCode=bichaw
http://www.jbc.org/content/236/12/3203.full.pdf
http://onlinelibrary.wiley.com/doi/10.1111/j.1432-1033.1970.tb00940.x/pdf
https://www.ncbi.nlm.nih.gov/pubmed/1642895
https://web.stanford.edu/~cpatton/MgATP-TS.htm
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