>1xbtB (B:) observed residues (from ATOM records)
rgqiqvilgpmfsgkstelmrrvrrfqiaqykclvikyakdtralpacllrdvaqealgv
avigidegqffpdivefceamanagktvivaaldgtfqrkpfgailnlvplaesvvklta
vcmecfreaaytkrlgtekeveviggadkyhsvcrlcyfk