Correct. (Documented on the ccpnmr mailing list awhile ago but not yet in
the offical documentation. Sounds like one for the wiki.)
So the equation
ChemShiftChange= (Kd + [ligand] + [protein] - Sqrt[(Kd + [ligand] + [protein])^2 - 4*
[ligand]*[protein]])/(2*[protein]) *maxChemShiftChange
gets mapped to:
y = A ((B+x)-sqrt((B+x)^2 - 4x))
where A = maxChemShiftChange/2, B = 1 + Kd/[protein], y = ChemShiftChange
and x = [ligand]/[protein].
Wayne
On Wed, 19 Nov 2008, Paul Driscoll wrote:
> Has anyone worked out, or is in any documentation anywhere, the
> 'translation' of the fitting function constants (e.g. A,B,C) in the
> DataAnalysis section of CCPNMR? We just spent the best part of a day on
> one of the quadratic equations (for ligand-binding titrations - chemical
> shift perturbation) and think we have right that, for example, B is
> equivalent to [1+(Kd/Ptot)]. We would like to know if we are right. [The
> reduced forms of the fitting functions are very clever, but perhaps not so
> straightforward for NMR students to employ without resorting to some
> algebra.]
>
> Cheers,
> Paul
>
> --
> Paul C Driscoll
> Professor of Structural Biology
> Research Department of Structural and Molecular Biology
> Division of Bioscience
> University College London
> Gower Street
> London WC1E 6BT
> Tel: +44 (0)20 7679 7035
>
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