passages.id: split_8_test_1081_passage
passages.type: progene_text
passages.text: Double mutants Cys(111) Ser / His(261) Ala and Cys(111) Ser / His(261) Arg were not able to catalyse overall condensation , but the double mutant containing Arg induced decarboxylation of [2-(14)C]malonyl-ACP , a reaction indicating the role of His(261) in general - acid catalysis .