Sigmoid

The shape of a binding hyperbola when the data are plotted on a logarithmic concentration scale (logarithmic X-axis). The same information can be obtained from the sigmoidal curve as can be obtained from a hyperbola; the X-value at which the degree of binding is 50% of Bmax is the log10KD value (or ln KD, if a natural logarithmic scale was used). The lower plateau of the sigmoid is typically 0 and the upper plateau is Bmax. In the presence of a competitive inhibitor or antagonist, the sigmoidal curve is shifted to the right.

An example of hyperbolic and sigmoidal binding curves is provided under the manual entry for hyperbola.

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An ABC of PK/PD Copyright © 2023 by Dr. Andrew Holt is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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