1.3.1.33 6.9 - - 393832 1.3.1.33 7.5 - - 698961 1.3.1.33 7.5 - activity assay 698913, 699004, 700758 1.3.1.33 7.5 - assay at 699004 1.3.1.33 7.5 - stopped-flow experiments 696223 1.3.1.33 8.5 - mutant y-7 393840