def ss_bridges(structure, asym_id_1, asym_id_2):
    """
    Iterate over the disulfide bridges in the structure.
    """
    for (asym1, comp1, seq1), (asym2, comp2, seq2) in structure.ss_bridges:
        if asym1 == asym_id_1 and asym2 == asym_id_2:
            yield seq1, seq2
        elif asym1 == asym_id_2 and asym2 == asym_id_1:
            yield seq2, seq1
