Can anyone advise on calculating unknown cAMP concentrations using the standard curve? I used the Cell Signaling Cyclic AMP XP® Chemiluminescent Assay Kit #8019. I obtained an exponential decay standard curve (or sigmoidal if I do logarithmic the cAMP concentration on the x axis), and none of the excel trend line options seems to fit well. We have GraphPad Prism 7 in our lab- I am not very familiar with it- and I could not find a good fit either. I don't know how to get a fitting equation for calculating unknown cAMP values. Any help, please?
As you said, one phase exponential decay is a good curve for your data, but you should directly use log [cAMP] for x-axis. In Prism, the standard curve can be fitted in "Analyze", "XY analyses", "Nonlinear regression (curve fitting)", and "One phase exponential decay". This allows for an estimation of the parameters S (max), P (min) and k (rate) of the equation
Y=S*e-kX+P.
This formula easily transforms measurements (Y) into concentrations (X). If you have difficulties, you can send me your data.
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