Fixing phi_ex or k_ex on R1rho fitsFixing phi_ex or k_ex on R1rho fitsDear Sirs and Mesdames,I am fitting my data with M61 model with relax. There is a somehow loosely defined canonical site in the protein, for which we know approximately the exchange parameters. However, there are more residues showing relaxation dispersion profiles and I would like to know if these residues could also belong to the canonical site. To address this problem, I have implemented a simple jackknifing procedure which precedes the fitting. Unfortunately, I very often encounter a situation where unrealistically high phi_ex values are fitted, resulting in very low exchange rates. I would like to restrict the phi_ex/k_ex values (either to a constant or to an interval of values) and compare the fit results manually. However, I was not able to find in the Relax tutorial if such a function exists for R1rho relaxation dispersion models (I am using scripts to run Relax).
Furthermore, I have encountered sometimes a situation where a flat line is fit to a data clearly showing relaxation dispersion, which is higher that the set INSIGNIFICANCE (I assume phi_ex is set to 0). Is there any explanation for that?
Thank you very much in advance and I apologize if my formulation was not very clear (I am a biologist and just relatively recently got into this stuff).
vilius