Dear all
We have a titration series that we wanted to analyze with the Follow Shift
Changes module.
As the binding event has a low Kd we simply wanted to fit the chemical shift
changes to:
dw = dwMAX * fractionBound = dwMAX * [ligand]/(Kd+[ligand])
The closest implementation of this equation is Ax/(1+Ax) where A = Ka. This
however requires that the chemical shift change you observe is normalized to
1 - and I guess that this is rarely the case.
The equation would be much more useful if it was modified to:
B*Ax/(1+Ax) {A=Ka; B = dwMAX}
or
B*x/(A+x) {A=Kd; B = dwMAX}
Cheers,
Kaare
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