passages.id: split_1_test_2813_passage
passages.type: progene_text
passages.text: To map the number and nature of the active sites of IF3 and to identify the essential Arg residue(s) chemically modified with 2,3-butanedione , the eight arginine residues of IF3C were substituted by Lys , His , Ser and Leu , generating 32 variants that were tested in vitro for all known IF3 activities .