As the PDB file contains no isotope information, this needs to now be specified. First click on the “X isotope” button to set the nuclear isotope type of the heteronuclei:
As nitrogen relaxation is being studied, the nuclear isotope name can be left as “15N” and the spin ID string to “@N*”. Therefore simply click on the “Ok” button. Exactly the same procedure can be used for the proton with the “H isotope” button.