>1xbtF (F:) observed residues (from ATOM records)
rgqiqvilgpmfsgkstelmrrvrrfqiaqykclvikyakdtralpacllrdvaqealgv
avigidegqffpdivefceamanagktvivaaldgtfqrkpfgailnlvplaesvvklta
vcmecfreaaytkrlgtekeveviggadkyhsvcrlcyfkk