Back to Analysis of Direct and Reverse Titrations

Tight, slow-off binding, fast isomerization

Fast isomerization removes any opportunity to detect multiple species. We will rely on fitting to the 2-site modela as a diagnostic tool.




U_R model: Fitting of the data simulated with different chemical shift separations

Common parameters we use are:

# Association constants
Ka_names A B
Ka 1e8 5

# Rate constants of REVERSE reactions
k_names A B
k2    1   200

between peaks/dw(B) 50/25 100/50 200/100 300/150 300/50 50/300

Simulate setup U_R_As_Bf_1

Simulate setup U_R_As_Bf_2

Simulate setup U_R_As_Bf_3

Simulate setup U_R_As_Bf_4

Simulate setup U_R_As_Bf_5

Simulate setup U_R_As_Bf_6
  Optimum norm: 3.83e-04
[1] Kd: 7.26225e-08 +/- 8.6e-09
[2] Koff: 9.39897e-01 +/- 1.0e-02
[3] Scale Factor: 2.04469e+00 +/- 8.8e-04
Optimum norm: 3.94e-04
[1] Kd: 6.27474e-08 +/- 5.4e-09
[2] Koff: 8.74077e-01 +/- 1.0e-02
[3] Scale Factor: 2.04367e+00 +/- 9.4e-04
Optimum norm: 1.16e-03
[1] Kd: 4.67171e-08 +/- 6.9e-09
[2] Koff: 8.05507e-01 +/- 1.9e-02
[3] Scale Factor: 2.02144e+00 +/- 1.8e-03
Optimum norm: 4.07e-03
[1] Kd: 2.69488e-06 +/- 3.3e-07
[2] Koff: 6.64336e-01 +/- 3.2e-02
[3] Scale Factor: 2.08585e+00 +/- 4.5e-03
Optimum norm: 5.46e-03
[1] Kd: 6.01641e-08 +/- 1.3e-08
[2] Koff: 8.93083e-01 +/- 4.0e-02
[3] Scale Factor: 2.04090e+00 +/- 3.9e-03
ptimum norm: 9.98e-04
[1] Kd: 2.77842e-08 +/- 4.8e-09
[2] Koff: 1.08003e+00 +/- 1.7e-02
[3] Scale Factor: 2.20594e+00 +/- 1.5e-03

No apparent dependence of fitted Kd on the offset.

Koff drops with combined dw of isomerization and binding.

This is a weak effect.






Back to Contents


  1. Slow binding and fast isomerization remove any features from the line shapes. No simple way of detecting complex mechanisms here.


Back to Analysis of Direct and Reverse Titrations