[BioPython] Bio.PDB: create a dummy vector

[Douglas Kojetin]

Hi All,

I would like to calculate the the angle between all of the N-H  
vectors in a PDB file to a specific point in 3D space.  Can someone  
tell me how to create a dummy atom using Biopython located at [0.0,  
0.0, 0.0]?

atom1 = structure[0]['A'][1]['H']
atom2 = structure[0]['A'][1]['N']

vector1=atom1.get_vector()
vector2=atom2.get_vector()
dummy = :: somehow create a point at [0.0, 0.0, 0.0] :::

angle=calc_angle(vector1,vector2,dummy)

Thanks,
Doug