I don´t trust SCK model adjustment. Do you?

Hello,

I recently performed a kinetic titration (Single Cycle Kineticks) with a Biacore T200 and CM5 sensor-chip to find the KD between a rat monoclonal antibody and a new protein. I immobilized 4000 RU of anti-Rat IgG, then I captured 100 RU of rat monoclonal antibody and then I injected 5 analyte concentrations going from 100 nM to 3500 nM. The curves look well but the 1:1 model doesn´t fit well, It looks so square and I´m wondering if I have to obtain new data or should I export the data I have and use different analysis method.
As always, thank you for your comments,

Oli

Hi Olivier,
It seems that the calculated RI is much too high.
You can try to fit the data but set first the RI (bulk refractive index) parameter to constant and zero.
When you have a decent fit then try to fit again, filling in the previous values and set RI to local.
You can also change the initial values to see if the fitting get better.
regards
Arnoud