NucProp

Nucleus properties (type, dipole, CSA)

‘info’ is a structure variable containing information about the experiments to be used for dynamics analysis. First, one must specify the properties of the nucleus being relaxed: the type of nucleus, the size of dipole coupling (to a bonded 1H), and the size of the chemical shift anisotropy (CSA). These may be specified for all experiments or for individual experiments. Backbone 15N, 13Cα, and 13CO have default settings so that one only needs to specify the nucleus. To simply use default settings, one sets:

info.Nuc='15N';       %Set to backbone '15N' defaults

The following table gives the defaults

String | 15N | 13Ca | 13CO
---------- | ---------- | ---------- | ------ |
Dipole | -22945 Hz | 44766 Hz | 0 Hz
CSA | 113 ppm | 20 ppm | 155 ppm

To override the defaults for all experiments (or specify CSA/dipole for a nucleus without defaults), one can specify:

 info.Nuc='13C';
 info.CSA=0;
 info.dHX=44766;

One may also set different values for the nucleus, CSA, and dipole for separate experiments. For example, if one acquires 2 R₁ experiments, then one could specify:

info.R1.Nuc={'15N','13CO'};   %Use a cell to contain the strings

This will use the backbone 15N and 13CO defaults for the two R₁ experiments. One may also specify the interactions separately:

info.R1.Nuc={'15N','13C'}
info.R1.CSA=[100 25];
info.R1.dHX=[22000 44000];

Finally, by default ‘calc_rates’ assumes the dipole coupling is to a proton (_{1H). This may be overridden by specifying the ‘info.Nuc1’ field.}

info.Nuc1='2H';       %Specify 2H instead of 1H
info.R1.Nuc1={'2H','1H'};    %Specify different coupled nuclei

Experimental settings