GE HEALTHCARE Biacore T100, Handbook

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9 Kinetics and affinity analysis
9.8 Predefined models
182
Biacore T100 Software Handbook BR-1006-48 Edition AE
9.8.3 Kinetics – Heterogeneous Analyte
This model is intended for analysis of the kinetics of interaction of mixtures of
two analytes that compete for the same ligand site. Experiments of this kind can
be used to deduce kinetic parameters for a low molecular weight analyte that
gives a small response from measurements of binding of a competing high
molecular weight analyte. Response contributions from both analytes are taken
into account, although the high molecular weight analyte is responsible for the
dominant component in the observed sensorgrams.
Concentrations and molecular weights are required for both analytes. If
absolute molecular weights are not known, relative values can be entered
without affecting the outcome of the fitting. The model cannot evaluate
interactions where the proportions and relative sizes of the analytes are
unknown.
A1 + B = A1B
A2 + B = A2B
Report parameters Calculated as
ka1 Association rate constant for the first site
(M
-1
s
-1
)
ka1
kd1 Dissociation rate constant for the first site (s
-1
) kd1
ka2 Association rate constant for the second site
(RU
-1
s
-1
)
ka2
kd2 Dissociation rate constant for the second site
(s
-1
)
kd2
Rmax Analyte binding capacity of the surface (RU) Rmax
Conc Analyte concentration (M) Conc
tc Flow rate-independent component of the mass
transfer constant tc
Flow Flow rate (µl/min) f
kt Mass transfer constant tc × f
1/3
RI Bulk refractive index contribution in the sample RI