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How Autodock 4 converts binding energy (kcal/mol) into Ki
Up to table of contentsThis FAQ applies to: AutoDock 4
Shows formula Autodock is using to convert binding energy into Ki.
This is taken from printEnergies.cc that is distributed with AutoDock source code:
See also: ADL: calculation of Ki in Autodock 4
// equilibrium: E + I <=> EI
// binding: E + I -> EI K(binding), Kb
// dissociation: EI -> E + I K(dissociation), Kd
//
// 1
// K(binding) = ---------------
// K(dissociation)
// so:
// ln K(binding) = -ln K(dissociation)
// ln Kb = -ln Kd
// Ki = dissociation constant of the enzyme-inhibitor complex = Kd
// [E][I]
// Ki = ------
// [EI]
// so:
// ln Kb = -ln Ki
// deltaG(binding) = -R*T*ln Kb
// deltaG(inhibition) = R*T*ln Ki
//
// Binding and Inhibition occur in opposite directions, so we
// lose the minus-sign: deltaG = R*T*lnKi, _not_ -R*T*lnKi
// => deltaG/(R*T) = lnKi
// => Ki = exp(deltaG/(R*T)) See also: ADL: calculation of Ki in Autodock 4