DynaFit Scripting Manual

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Linked concentrations

Two or more concentrations can be linked together, meaning that their values are either identical or related through a constant factor.

[concentrations]
   A = 1.00 ? 
   B = A    ; <=== linkage

For example, an enzyme inhibitor might be a 1:1 mixture of two enantiomers with S and R stereochemical configuration, respectively. Let us assume that the dose-response curve was measured by varying the concentration of the inhibitor between zero to 100 $\mu$M. Let us also assume that both enantiomers have nonzero inhibitory activity, measured by the inhibition constants $K_{i(S)}$ and $K_{i(R)}$, respectively. In this case the concentration of the S and the R enantiomers are varied simultaneously. This can be indicated in the script file by making the S enantiomer as the varied component, and then linking the concentration of the R enantiomer via the relationship $c_{\scriptscriptstyle \rm S} = c_{\scriptscriptstyle \rm R}$.

[mechanism]
   E + A <==> E.A       : Ka    dissoc
   E.A --> E + P        : kcat
   E + (S)I <==> E.(S)I : Ki(S) dissoc
   E + (R)I <==> E.(R)I : Ki(R) dissoc
[constants]
   Ka = 100, kcat = 10
   Ki(S) = 0.01
   Ki(R) = 0.1
[concentrations]
      E = 0.010 ?
   (R)I = (S)I   ;  <=== linkage
[responses]
   P = 1
[velocities]
   variable (S)I ;  <=== (R)I varied also
   file f1 | concentration S = 10
[end]

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Petr Kuzmic | Jul 12 2005