[ccp4bb] Angle between monomer of a dimer

[Appu kumar]

Dear all ccp4 users,
                                  I have solved the structure of a protein
which is a dimer. On comparison with the other structure from PDB data
bank, i found that structure solved by us show a tiltness in
monomer-monomer arrangement of a dimer. May you please help me in findng
the angle between two monomer. Do i need to calculate the centre of mass of
the protein for calcualting the angle between them?.
Thanks in advance please help me.
Thank you
Appu