Data items in the STRUCT_SHEET_TOPOLOGY category record details about the topology of the residue ranges that form a beta-sheet. All topology links are pairwise and the specified pairs are assumed to be successive in the amino-acid sequence. These data items are useful in describing various simple and complex folds, but they become inadequate when the strands in the sheet come from more than one chain. The STRUCT_SHEET_ORDER data items can be used to describe single- and multiple-chain-containing sheets.
loop_ _struct_sheet_topology.sheet_id _struct_sheet_topology.range_id_1 _struct_sheet_topology.range_id_2 _struct_sheet_topology.offset _struct_sheet_topology.sense sheet_1 strand_a strand_b +1 parallel sheet_1 strand_b strand_c +1 parallel sheet_1 strand_c strand_d +1 parallel sheet_1 strand_d strand_e +1 parallel sheet_1 strand_e strand_f +1 parallel sheet_1 strand_f strand_g +1 parallel sheet_1 strand_g strand_h +1 parallel sheet_1 strand_h strand_a +1 parallel
loop_ _struct_sheet_topology.sheet_id _struct_sheet_topology.range_id_1 _struct_sheet_topology.range_id_2 _struct_sheet_topology.offset _struct_sheet_topology.sense sheet_2 strand_a strand_c +2 anti-parallel sheet_2 strand_c strand_d1 +1 anti-parallel sheet_2 strand_d1 strand_e +1 anti-parallel sheet_2 strand_e strand_d2 -1 anti-parallel sheet_2 strand_d2 strand_b -2 anti-parallel