strand() -- make a $\beta$ -strand

strand(residues)

This makes restraints enforcing an extended $\beta$ -strand conformation for the residue segment specified by residues (which can be created using the model.residue_range() function). This is achieved by applying $\Phi,\Psi$ binormal restraints only. These binormal restraints force the mainchain conformation into class ``B'', except for the Pro residues which are restrained to class ``P'' [Š ali & Blundell, 1993].

To actually add the restraints, pass the new object to restraints.add(). See Section 2.2.9 for an example.