GE HEALTHCARE Biacore T100, Handbook

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Biacore T100 Software Handbook BR-1006-48 Edition AE
201
Thermodynamic analysis 10
Choose whether to use a linear or non-linear fitting function for the van’t Hoff
plot (see Section 10.1.1). If you choose non-linear fitting, a value for
Δ
C
p
will be
included in the reported parameters. Energies of activation (E
a
), derived from the
Eyring plots, are also listed for the transition states. All thermodynamic
parameters are calculated for a temperature of 25°C.
In any of the plots, right click on a point to exclude it from the evaluation.
Notes: Regardless of the setting for the van’t Hoff plot, the Eyring plots are
always fitted to a linear function. Calculation of
Δ
C
p
by non-linear fitting
is not valid for transition state data (see Section 10.1.2).
If you have combined kinetic and steady state affinity data in the
thermodynamic evaluation, the van’t Hoff plot will show all affinity values,
but the Eyring plots will be empty because the steady state data lacks
values for the rate constants.
Plots of kinetic and affinity constants against temperature show
temperature values in °C, while van’t Hoff and Eyring plots use absolute
temperature values (K).
Click on Finish to finalize the thermodynamic analysis.
When assessing the validity of thermodynamic constants reported by this
analysis procedure, pay particular attention to the kinetic analysis at different
temperatures. With complex interactions involving macromolecules, there is a
significant possibility that the characteristics of the interaction (including the
role of mass transport limitations in the observed interaction) change with
temperature, resulting in different fitting quality at different temperatures. This
may be evident from direct comparison of the kinetic fits, but will not be
immediately apparent in the thermodynamic analysis.