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

sheet(atom1, atom2, sheet_h_bonds)
This calculates H-bonding restraints for a pair of $ \beta $ -strands. atom1 and atom2 specify the first H-bond in the $ \beta $ -sheet ladder. sheet_h_bonds specifies the number of H-bonds to be added -- positive for a parallel sheet, and negative for an anti-parallel sheet. In a parallel sheet, hydrogen bonds start at the first or the second term of the following series (depending on atom1 and atom2): 1N:1O, 1O:3N, 3N:3O, 3O:5N, etc. For an anti-parallel sheet, the corresponding series is 1N:3O, 1O:3N, 3N:1O, 3O:1N, etc. (note that the residue indices run in decreasing order for the second strand in this case). The extended structure of the individual strands themselves is not enforced; use separate strand() restraints if so desired.

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

Ben Webb 2007-01-19