passages.id: split_8_test_618_passage
passages.type: progene_text
passages.text: Two autonomous folding units , comprising the first six strands ( residues 1 - 188 ) and the last two strands ( residues 189 - 268 ) , have been previously identified in this single structural domain protein by tryptic digestion [ Higgins , W. , Fairwell , T. , and Miles , E. W. ( 1979 ) Biochemistry 18 , 4827 - 4835 ] .