Dear Ram Kumar,
You could use Ramachandran. If you do something like the following:
Kumar = ramachandran('Your_PDB_database_identifier')
You will have the 1x1 struct 'Kumar' in your workspace. Access the angles (phi, psi and omega) by:
You could also do it as D'Errico described. In that case you could just open a *.PDB file as follows:
Kumar_pdbstruct = pdbread('your_pdb_file_name.pdb');
And then access the XYZ coordinates using
There you will have the XYZ coordinates of every atom in the protein model, and you can calculate the corresponding dihedral angles yourself.