passages.id: split_8_test_1183_passage
passages.type: progene_text
passages.text: Acylation of a unique cysteine residue introduced at the extreme C terminus of the p66 subunit ( C(561) ) with an azidophenacyl group allowed us to probe contacts between residues C - terminal to alpha - helix E' of the RNase H domain and structurally divergent nucleic acid duplexes .